Department of Health and Human Services

OFFICE OF 

INSPECTOR GENERAL 

 

ADVERSE EVENTS IN HOSPITALS:

NATIONAL INCIDENCE AMONG 

MEDICARE BENEFICIARIES 

 

Daniel R. Levinson 

Inspector General 

November 2010 

OEI-06-09-00090 
 EXECUTIVE SUMMARY 

OBJECTIVES

To estimate the national incidence of adverse events for hospitalized 

Medicare beneficiaries, assess the preventability of such events, and 

estimate associated costs to Medicare. 

BACKGROUND 

The term “adverse event” describes harm to a patient as a result of 

medical care, such as infection associated with use of a catheter. The 

term “never events” refers to a specific list of serious events, such as 

surgery on the wrong patient, that the National Quality Forum (NQF) 

deemed “should never occur in a health care setting.” The Tax Relief 

and Health Care Act of 2006 mandates that the Office of Inspector 

General report to Congress regarding the incidence of never events 

among Medicare beneficiaries, the payment for services in connection 

with such events, and the Centers for Medicare & Medicaid Services 

(CMS) processes to identify events and deny payment. 

We selected a nationally representative random sample of 780 Medicare 

beneficiaries from all beneficiaries discharged during October 2008. 

Physician reviewers determined (1) whether an adverse event occurred, 

(2) whether the event was on the NQF list of Serious Reportable Events 

or the Medicare list of hospital-acquired conditions (HAC), (3) what the 

level of harm was to the patient, and (4) whether the event was 

preventable. To establish an estimated adverse event incidence rate, we 

included events on the NQF and the HAC lists and events resulting in 

the most serious harm as defined by a patient harm index (prolonged 

hospital stay, permanent harm, life-sustaining intervention, or death). 

We also determined the cost to Medicare for hospital care resulting from 

the events. Lastly, we identified additional events that resulted in 

temporary patient harm but were not comparable to the more serious 

events in our overall rate and assessed their preventability and cost. 

FINDINGS 

An estimated 13.5 percent of hospitalized Medicare beneficiaries 

experienced adverse events during their hospital stays. Of the 

nearly 1 million Medicare beneficiaries discharged from hospitals in 

October 2008, about 1 in 7 experienced an adverse event that met at 

least 1 of our criteria (13.5 percent). This rate projects to an estimated 

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EXECUTIVE SUMMARY 

134,000 Medicare beneficiaries experiencing at least 1 adverse event in 

hospitals during the 1-month study period. We calculated incidence 

rates for adverse events that met our three criteria: 0.6 percent of 

beneficiaries had an NQF Serious Reportable Event, 1.0 percent had a 

Medicare HAC event, and 13.1 percent experienced an adverse event 

resulting in the four most serious categories of patient harm. An 

estimated 1.5 percent of Medicare beneficiaries experienced an event 

that contributed to their deaths, which projects to 15,000 patients in a 

single month. 

An additional 13.5 percent of Medicare beneficiaries experienced 

events during their hospital stays that resulted in temporary harm. 

Temporary harm events are those that require intervention but do not 

cause lasting harm. Although many cases represent fairly minor 

occurrences, such as hypoglycemia, others were classified as temporary 

harm only because the patients were in the hospital for lengthy periods 

as a result of other, more serious, diagnoses, allowing hospitals enough 

time to address the harm prior to discharge. Additionally, 28 percent of 

beneficiaries who experienced adverse events also had temporary harm 

events during the same stay. 

Physician reviewers determined that 44 percent of adverse and 

temporary harm events were clearly or likely preventable. 

Physicians determined that 44 percent of all events were preventable 

and 51 percent were not preventable. (For the remaining 5 percent of 

events, physicians were unable to make determinations.) Events 

related to surgery or procedures were less likely to be preventable than 

other types of events, such as hospital-acquired infections. Preventable 

events were linked most commonly to medical errors, substandard care, 

and lack of patient monitoring and assessment. Physician reviewers 

assessed events as not preventable when they occurred despite proper 

assessment and care or when the patients were highly susceptible to the 

events due to health status. Nearly all events on the NQF and Medicare 

lists were assessed as preventable, a key criterion of both lists. 

Hospital care associated with adverse and temporary harm events 

cost Medicare an estimated $324 million in October 2008. 

Sixteen percent of sample beneficiaries in the Medicare Inpatient 

Prospective Payment System who experienced events incurred 

additional Medicare costs as a result. The added costs equate to an 

estimated 3.5 percent of Medicare’s expenditure for inpatient care 

during October 2008. To give these figures an annual context, 

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EXECUTIVE SUMMARY 

3.5 percent of the $137 billion Medicare inpatient expenditure for 

FY 2009 equates to $4.4 billion spent on care associated with events. 

Two-thirds of Medicare costs associated with events were the result of 

entire additional hospital stays necessitated by harm from the events. 

Additionally, these Medicare cost estimates do not include additional 

costs required for followup care after the sample hospitalizations. 

RECOMMENDATIONS 

As the Federal Government’s principal agency for protecting the health 

of Americans, the Department of Health & Human Services (HHS) is 

uniquely positioned to lead national efforts to reduce adverse events in 

hospitals. As part of a national strategy to improve health care quality 

mandated by the Patient Protection and Affordable Care Act (ACA), 

HHS is to identify areas that have the potential for improving health 

care quality. Because many adverse events we identified were 

preventable, our study confirms the need and opportunity for hospitals 

to significantly reduce the incidence of events. A number of agencies 

within HHS share responsibility for addressing this issue, most 

prominently the Agency for Healthcare Research and Quality (AHRQ) 

as a coordinating body for efforts to improve health care quality and 

CMS as an oversight entity and the Nation’s largest health care payer. 

Therefore, we recommend the following: 

AHRQ and CMS should broaden patient safety efforts to include 

all types of adverse events. This broader definition would apply to 

a number of activities, including setting priorities for research, 

establishing guidelines for hospital reporting, developing prevention 

strategies, measuring health care quality, and determining payment 

policies. 

AHRQ and CMS should enhance efforts to identify adverse events. 

Identifying adverse events assists policymakers and researchers in 

directing resources to the areas of greatest need, setting clear goals for 

improvement, assessing the effectiveness of specific strategies, holding 

hospitals accountable, and gauging progress in reducing incidence. 

 AHRQ should sponsor periodic, ongoing measurement of the 

incidence of adverse events. 

 AHRQ should continue to encourage hospital participation with 

Patient Safety Organizations, entities intended to receive adverse 

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EXECUTIVE SUMMARY 

event reports from hospitals, and forward the information to a 

national AHRQ database. 

 CMS should use Present on Admission Indicators in billing data to 

calculate the frequency of adverse events occurring within hospitals. 

CMS should provide further incentives for hospitals to reduce the 

incidence of adverse events through its payment and oversight 

functions. The ACA makes several changes to the HAC policy, 

including allowing the Secretary of HHS to expand the list of HACs. 

The ACA gives the HAC policy greater significance by using the list of 

HACs to implement Medicare payment penalties, create performance 

measures, and prohibit Medicaid payments for associated care. The 

conditions of participation for Medicare and Medicaid require that 

hospitals have programs to demonstrate quality improvement where 

evidence shows practices can improve outcomes. 

 CMS should strengthen the Medicare HAC policy, such as by 

expanding the policy to include more events that harm beneficiaries. 

 CMS should look for opportunities to hold hospitals accountable for 

adoption of evidence-based practice guidelines. 

AGENCY COMMENTS 

We received comments on the draft report from AHRQ and CMS. 

AHRQ concurred with our recommendations, stating that adverse 

events affect hospital patients at an “alarming rate” and that it must 

continue working to improve patient safety. AHRQ stated that it 

intends to foster continued improvement in both identifying and 

reducing adverse events through operational programs, research efforts, 

and further collaboration with other agencies. CMS also concurred with 

our recommendations, stating that it is committed to the reduction of 

adverse events in hospitals and other health care settings and that 

although it has taken significant steps to address these issues, more 

work needs to be done. CMS stated that it will “aggressively pursue” 

broadening the scope and definition of patient safety efforts to be more 

inclusive of various types of adverse events and more closely monitor 

and address hospital quality of care. CMS also outlined several current 

and planned efforts to both create incentives and provide support for 

patient safety improvements by hospitals. 

We made minor changes to the report based on technical comments. 

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 TABLE OF CONTENTS 

EXECUTIVE SUMMARY .....................................i 

INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 

FINDINGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 

An estimated 13.5 percent of hospitalized Medicare beneficiaries 

experienced adverse events during their hospital stays. . . . . . . . . . . . . 15 

An additional 13.5 percent of Medicare beneficiaries experienced 

events during their hospital stays that resulted in temporary harm . . . 20 

Physician reviewers determined that 44 percent of adverse events 

and temporary harm events were clearly or likely preventable. . . . . . . 22 

Hospital care associated with adverse events and temporary harm 

events cost Medicare an estimated $324 million in October 2008 . . . . . 27 

RECOMMENDATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 

 Agency Comments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 

APPENDIXES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 

 A: Tax Relief and Health Care Act of 2006 . . . . . . . . . . . . . . . . . . . . . . 35 

 B: National Quality Forum Serious Reportable Events . . . . . . . . . . . . 37 

C: Medicare Hospital-Acquired Conditions . . . . . . . . . . . . . . . . . . . . . . 38 

D: Glossary of Selected Terms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 

E: Methodology for Identifying Events and Determining 

Preventability. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 

F: Estimates, Confidence Intervals, and Key Statistics . . . . . . . . . . . . 46 

G: Rates of Adverse Events and Temporary Harm Events by 

Patient Days and Hospital Admissions . . . . . . . . . . . . . . . . . . . . . . 50 

H: Adverse Events and Temporary Harm Events . . . . . . . . . . . . . . . . . 51 

I: Agency Comments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62 

ACKNOWLEDGMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74


 INTRODUCTION 

OBJECTIVES 

To estimate the national incidence of adverse events for hospitalized 

Medicare beneficiaries, assess the preventability of such events, and 

estimate associated costs to Medicare. 

BACKGROUND 

Statutory Mandate and Office of Inspector General Response 

The Tax Relief and Health Care Act of 2006 (the Act) requires that the 

Office of Inspector General (OIG) report to Congress regarding the 

incidence of “never events” among Medicare beneficiaries; the extent to 

which the Medicare program paid, denied payment, or recouped 

payment for services furnished in connection with such events; and the 

processes that the Centers for Medicare & Medicaid Services (CMS) 

uses to identify such events and deny or recoup payment.1 OIG is also 

to make recommendations for such legislation and administrative action 

as OIG determines is appropriate. (For relevant text of the Act, see 

Appendix A.) To meet the requirements of the Act, OIG released a 

series of reports beginning in 2008 and will publish additional reports 

based on ongoing work.2 

Adverse Events in Hospitals 

Following a review of Medicare policies and expenditures, as well as 

consultation with CMS and the Agency for Healthcare Research and 

Quality (AHRQ), we chose to focus our work on inpatient acute care 

hospitals. For fiscal year (FY) 2009, Medicare costs for inpatient care 

were $137 billion, constituting 28 percent of total expenditures.3 As a 

condition of participation in the Medicare and Medicaid programs, 

Federal regulations require that hospitals develop and maintain Quality 

Assessment and Performance Improvement (QAPI) Programs.4 As a 

1 Tax Relief and Health Care Act of 2006, P.L. 109-432 § 203. 

2 The studies in the series published to date are: Adverse Events in Hospitals: Overview of 

Key Issues, OEI-06-07-00470; Adverse Events in Hospitals: State Reporting Systems, 

OEI-06-07-00471; and Adverse Events in Hospitals: Case Study of Incidence Among Medicare 

Beneficiaries in Two Counties, OEI-06-08-00220, all published in December 2008; Adverse 

Events in Hospitals: Public Disclosure of Information About Events, OEI-06-09-00360, 

January 2010; and Adverse Events in Hospitals: Methods for Identifying Events, 

OEI-06-08-00221, March 2010. 

3 CMS, 2009 CMS Statistics Book, Table III.6, Office of Research, Development, and 

Information, CMS Pub. No. 03497, December 2009, p. 30. 

4 42 CFR § 481.21. 

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INTRODUCTION 

part of their QAPI programs, hospitals must “track medical errors and 

adverse patient events, analyze their causes, and implement preventive 

actions.”5 Federal regulations do not require specific program 

characteristics. The QAPI provisions also require that hospitals 

establish programs to demonstrate improvement in quality indicators 

for which there is evidence that practices will improve outcomes.6 As an 

additional quality effort, Quality Improvement Organizations (QIO) 

contract with CMS to assist hospitals in improving the quality of care 

for Medicare beneficiaries, including addressing patient safety issues.7 

A variety of terms, lists, and definitions are used to identify health care 

events that result in patient harm. For purposes of the Act, the term 

“never event” means an event that is listed and endorsed as a serious 

reportable event by the National Quality Forum (NQF)8 as of 

November 16, 2006.9 The NQF uses the term “serious reportable 

events” to describe a specific list of events associated primarily with 

patient death or serious disability that are both egregious and 

preventable, concluding that they “should never occur in a health care 

setting.” These became known as “never events.” (For a list of NQF 

Serious Reportable Events, see Appendix B.) The NQF list is often used 

by patient advocates and health care payers in establishing patient 

safety policies.10 The health care community now uses the term 

“adverse event” more commonly than “never event” to refer to harm 

experienced by a patient as a result of medical care. After consulting 

with congressional committee staff in 2007, we expanded our approach 

to be consistent with patient safety research and industry trends. 

As used in this study, an adverse event is defined as harm to a patient 

as a result of medical care or in a health care setting. Although an 

adverse event indicates that the care resulted in an undesirable clinical 

5 42 CFR § 482.21(c)(2). 

6 42 CFR § 482.21(a)(1). 

7 CMS, QIO Overview, last modified January 2010. Accessed at 

http://www.cms.hhs.gov/QualityImprovementOrgs/ on September 29, 2010. 

8 NQF is a public-private membership organization created to develop and implement a 

national strategy for health care quality measurement and reporting. 

9 The Act, § 203(d). The NQF list is available online at http://www.qualityforum.org. 

10 As an example, The Leapfrog Group, a national nonprofit focused on patient safety 

issues, encourages hospitals to adopt policies to address Serious Reportable Events. Leapfrog 

Group Position Statement on Never Events, updated November 11, 2009. Accessed at 

http://www.leapfroggroup.org/for_hospitals/leapfrog_hospital_survey_copy/never_events on 

September 29, 2010. 

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INTRODUCTION 

outcome and may involve medical errors, adverse events do not always 

involve errors, negligence, or poor quality of care and are not always 

preventable.11 Research and policy to improve patient safety and 

reduce the incidence of adverse events often focus on identifying and 

addressing systemic problems that may lead to patient harm and avoid 

labeling the event as an outcome of negligence or poor quality. 

Additionally, researchers, policymakers, and health care entities 

sometimes adopt different standards for distinguishing between degrees 

of patient harm in determining whether they classify an occurrence as 

an adverse event. Thus, entities tracking events may find different 

results depending on the list used to identify and classify events. 

The National Coordinating Council for Medication Errors Reporting and 

Prevention (NCC MERP) Index for Categorizing Errors can be used to 

classify adverse events by level of patient harm. The NCC MERP Index 

was initially developed to categorize the effect of medication errors and 

considers whether the occurrences had an effect on the patients and, if 

so, how harmful they were. The index includes categories for 

circumstances or occurrences that presented a risk but did not cause 

harm, often referred to as “near misses,” and those that caused harm. 

Table 1 shows the NCC MERP Index for Categorizing Errors. 

Table 1: The NCC MERP Index for Categorizing Errors 

Level Description Event 

A Circumstances or events occurred that had the capacity to cause error. 

B Error occurred but did not reach the patient. 

C Error occurred that reached the patient but did not cause patient harm. 

D Error occurred that reached the patient and required monitoring to 

preclude harm or confirm that it caused no harm. 

Harm 

does not 

reach 

patient 

E Error occurred that may have contributed to or resulted in temporary 

harm and required intervention. 

F Error occurred that may have contributed to or resulted in harm and 

required an initial or prolonged hospital stay. 

G Error occurred that contributed to or resulted in permanent patient harm. 

H Error occurred that required intervention to sustain the patient’s life. 

I Error occurred that may have contributed to or resulted in patient death. 

Harm 

reaches 

patient 

Source: NCC MERP Index for Categorizing Errors, Press Release, Medication Errors Council Revises and 

Expands Index for Categorizing Errors: Definitions of Medication Errors Broadened, June 12, 2001.

11 R.M. Wachter, Understanding Patient Safety, McGraw-Hill, 2008. 

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INTRODUCTION 

Researchers have used the NCC MERP index for measuring and 

distinguishing other types of adverse events, rather than only 

medication errors. For example, the Institute for Healthcare 

Improvement (IHI), a nonprofit organization that advises hospitals 

regarding health care quality, uses a modified version of the 

NCC MERP index to measure the degree of patient harm, regardless of 

whether the harm was the result of an error. 12

Present on Admission Indicators and Medicare’s Hospital-Acquired 

Conditions Policy 

Medicare reimbursement to acute care hospitals through the Inpatient 

Prospective Payment System (IPPS) is generally determined by 

grouping codes representing patient conditions into Diagnosis-Related 

Groups (DRG) based on the average cost of care for patients with 

similar conditions.13 Hospitals may submit Medicare claims under 

IPPS using nine diagnosis codes and six procedure codes for each 

hospital stay. Historically, if a Medicare beneficiary experienced an 

adverse event that resulted in assignment of a more costly DRG, CMS 

paid the higher DRG.14 

Beginning October 1, 2007, hospitals are required to assign a Present on 

Admission (POA) Indicator to each principal and secondary diagnosis 

for acute IPPS claims for all discharges.15 This was an initial step in 

complying with the Deficit Reduction Act of 2005 (DRA), which required 

CMS to select at least two hospital-acquired conditions (HAC) for which 

hospitals would not be paid higher Medicare reimbursement.16 

12 F.A. Griffin and R.K. Resar, IHI Global Trigger Tool for Measuring Adverse Events, 

Institute for Healthcare Improvement Innovation Series 2007, pp. 4–5. 

13 CMS, Acute Inpatient PPS Overview, last modified Feb. 22, 2010. The ICD-9-CM system 

assigns diagnoses and procedure codes associated with hospital stays and is maintained 

jointly by CMS and the National Center for Health Statistics. Accessed at 

http://www.cms.gov/AcuteInpatientPPS/01_overview.asp on September 29, 2010. 

14 CMS, Press Release, Eliminating Serious, Preventable, and Costly Medical Errors – 

Never Events, May 18, 2006. 

15 CMS, CMS Manual System, Change Request 5679 (July 20, 2007). To effectuate the use 

of POA indicators, the FY 2008 IPPS rule implemented a more specific list of DRGs called 

Medicare Severity Diagnosis-Related Groups (MS-DRG). MS-DRGs split some of the prior 

DRGs into two or three classes based on the presence of a complication or comorbidity. 

FY 2008 IPPS Final Rule, 72 Fed. Reg. 47130, 47138 (Aug. 22, 2007). 

16 DRA, P.L. 109-171 § 5001(c)(1), Social Security Act (SSA), § 1886(d)(4)(D), 

42 U.S.C. § 1395ww(d)(4)(D). 

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INTRODUCTION 

In response, CMS issued regulations outlining a policy to deny hospitals 

higher payment for hospital admissions complicated by any of 

10 categories of HACs.17 The DRA required that the conditions meet 

the following criteria: 

 conditions that are high cost, high volume, or both; 

 conditions that, when present as a secondary diagnosis, result in 

assignment of a case to a DRG that has a higher payment; 

 conditions that could be reasonably prevented by using readily 

available evidence-based guidelines; and 

 conditions that are identifiable based on one or more unique 

diagnosis codes.18 

Effective October 1, 2008, CMS began denying hospitals higher payment 

for care associated with these conditions.19 Examples of HACs include 

catheter-associated urinary tract infections and patient injury because 

of a fall. For the full list of Medicare HACs, see Appendix C. 

Determining the Incidence of Adverse Events 

Research indicates that identifying adverse events retrospectively is a 

complex and difficult task, requiring extensive clinical knowledge, 

adequate documentation, and subjectivity on the part of the 

researcher.20 Medical records review is often considered the most 

definitive method for detecting adverse events because it can provide 

detail about both the adverse event and the circumstances, such as the 

patient’s condition prior to and following the event.21 However, medical 

records reviews can be costly, requiring hospital staff to make records 

available and substantial effort by physicians or other clinicians to 

review them. To limit physician medical records reviews required to 

identify adverse events, cases can be screened to identify potential 

17 FY 2008 IPPS Final Rule, 72 Fed. Reg. 47130, 47202 (Aug. 22, 2007); and FY 2009 IPPS 

Final Rule, 73 Fed. Reg. 48434, 48471–48491 (Aug. 19, 2008). 

18 SSA, § 1886(d)(4)(D)(iv). 

19 FY 2009 IPPS Final Rule, 73 Fed. Reg. 48434, 48471–48472 (Aug. 19, 2008); CMS, CMS 

Manual System, Change Request 6189 (Oct. 3, 2008). 

20 E.J. Thomas and L.A. Peterson, Measuring Errors and Adverse Events in Health Care, 

Journal of General Internal Medicine, 18(1), 2003, pp. 61–67. 

21 E.J. Thomas, D.M. Studdert, and T.A. Brennan, The Reliability of Medical Record 

Review for Estimating Adverse Event Rates, Annals of Internal Medicine, 136(11), June 2002, 

pp. 812–816. 

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INTRODUCTION 

adverse events using other methods, such as nurse reviews of medical 

records and analysis of POA indicators in hospital claims data. 

Nurse review of medical records. Medical records screening can identify 

potential adverse events based on information in the medical records. 

The IHI Global Trigger Tool (GTT) uses a review of medical records to 

identify “triggers” that could signal patient harm, thereby identifying 

potential adverse events. A trigger could be a description of the harm 

itself or a reference that indicates harm occurred (such as a return to 

surgery). The review is designed to be completed by nurse reviewers, 

with the results then confirmed or refuted by a physician. Barriers to 

medical records screening include incomplete records and high labor 

costs for review. 

Analysis of POA indicators. Automated computer programs can review 

Medicare billing data, specifically the POA indicator codes assigned to 

each diagnosis, to identify conditions that developed during hospital 

stays and possibly constitute adverse events. Although these programs 

enable examination of large numbers of hospital stays, barriers exist to 

POA analysis, including inaccurate or incomplete data. CMS’s POA 

coding requirement began in October 2007, and the accuracy and 

completeness of hospital coding of POA indicators have not yet been 

validated. Additionally, conditions can be acquired in hospitals that are 

not related to medical care and therefore not adverse events.

OIG case study. Prior to this study, we conducted a case study of the 

incidence of adverse events occurring during October 2008 for a random 

sample of 278 Medicare beneficiaries’ hospital stays in 2 counties.22 We 

estimated that 15 percent of Medicare beneficiaries in the two counties 

experienced events meeting at least one of the following criteria: events 

on the NQF list of Serious Reportable Events; events on Medicare’s list 

of HACs; or events involving prolonged hospital stays, permanent harm, 

life-sustaining intervention, or death (classified as F-I level of harm on 

the NCC MERP index). An additional 15 percent of beneficiaries 

experienced events involving temporary harm (classified as E level of 

harm on the NCC MERP index). The case study served in part to test 

the usefulness of various methods for identifying adverse events. We 

found that, combined, nurse screening of medical records and analysis 

22 OIG, Adverse Events in Hospitals: Case Study of Incidence Among Medicare 

Beneficiaries, OEI-06-08-00220, December 2008. 

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INTRODUCTION 

of POA indicator codes in billing data identified 94 percent of 

occurrences that physicians ultimately determined to be adverse or 

temporary harm events.23

Determining the Preventability of Adverse Events 

To provide additional context regarding adverse events, some 

researchers have assessed whether adverse events were preventable 

and described the circumstances associated with events. A 2008 

review of eight preventability studies found that the median percentage 

of adverse events judged preventable was 43.5 percent.24 Assessing 

preventability can provide greater understanding of the causes of 

adverse events, which can be used to develop actionable solutions to the 

systemic problems that lead to events. Also, preventability is a 

statutory criterion of Medicare’s nonpayment policy for HACs; CMS was 

required to select only conditions that can be “reasonably prevented by 

using readily available evidence-based guidelines.”25

Reducing the Incidence of Adverse Events 

Reducing the incidence of adverse events in hospitals is a critical 

component of efforts to improve patient safety and quality care. The 

Institute of Medicine (IOM) report, To Err Is Human: Building a Safer 

Health System, focused widespread attention on the problem of adverse 

events. IOM cited two studies that used medical records reviews to 

identify adverse events and assess whether events were preventable. 

IOM concluded that preventable adverse events caused “at least 

44,000 and perhaps as many as 98,000 deaths in hospitals each year” 

and outlined a national plan to address adverse events.26 

As part of its plan, IOM recommended the creation of a nationwide 

system for the collection of standardized adverse event data by State 

governments. As reported by OIG, 25 States and the District of 

Columbia had adverse event reporting systems in 2008, 11 of which 

23 OIG, Adverse Events in Hospitals: Methods for Identifying Events, OEI-06-08-00221, 

March 2010. 

24 E.N. De Vries, M.A. Ramrattan, et al., The Incidence and Nature of In-Hospital Adverse 

Events: A Systematic Review, British Medical Journal – Quality and Safety in Health Care, 

17(3): 216–23, June 2008. 

25 SSA, § 1886(d)(4)(D)(iv), 42 CFR § 412.10; FY 2008 IPPS Final Rule, 72 Fed. Reg. 47130, 

47202 (Aug. 22, 2007). 

26 L.T. Kohn, J.M. Corrigan, and M.S. Donaldson, eds., To Err Is Human: Building a Safer 

Health System, A Report of the Committee on Quality of Health Care in America, p. 102, 

IOM, National Academy Press, 2000. 

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INTRODUCTION 

used the NQF list of Serious Reportable Events or a modified version of 

the list to define what events are reportable.27 To date, no national 

adverse event reporting system exists and there are no Federal 

standards regarding State systems. 

Following the IOM report, the Federal Government formed the Center 

for Quality Improvement and Patient Safety (CQuIPS) within AHRQ to 

provide national leadership in improving patient safety. In a 2009 

report, AHRQ identified its core agency objectives for CQuIPS as 

developing a solid evidence base, designing useful tools for providers, 

and disseminating information for implementation.28 As mandated by 

Congress, AHRQ releases an annual report to the Nation about health 

care quality that is produced by CQuIPS and includes measures of 

patient safety.29 The National Healthcare Quality Report includes 

measures of the incidence of certain types of adverse events, using data 

from sources such as the Medicare Patient Safety Monitoring System 

(MPSMS), an AHRQ-CMS collaborative effort to identify adverse events 

through analyses of medical records and Medicare claims data for 

beneficiaries’ hospital stays.30 AHRQ is also responsible for 

implementation and oversight of the certification process for Patient 

Safety Organizations (PSO) created by the Patient Safety Act and 

Quality Improvement Act of 2005.31 PSOs are in the early stages of 

development, but are intended to receive adverse event reports from 

hospitals and forward the information to a national AHRQ database 

from which CQuIPS will analyze aggregated data. AHRQ developed a 

set of event definitions and reporting tools known as the Common 

Formats, which PSOs can choose to use and which contain data 

elements that AHRQ determined are important for a complete and 

27 OIG, Adverse Events in Hospitals: State Reporting Systems, OEI-06-07-00471, 

December 2008. 

28 AHRQ, Advancing Patient Safety: A Decade of Evidence, Design, and Implementation, 

AHRQ Publication No. 09(10)-0084, November 2009. Accessed at 

http://www.ahrq.gov/qual/advptsafety.htm on September 29, 2010. 

29 Healthcare Research and Quality Act of 1999, P.L. 106-129 § 2(a); Public Health Service 

Act (PHSA), § 913, 42 U.S.C. § 299b-2. 

30 D.R. Hunt, N. Verzier, et al., “Fundamentals of Medicare Patient Safety Surveillance: 

Intent, Relevance, and Transparency,” Advances in Patient Safety, 2005, p. 105. Accessed at 

www.ahrq.gov/downloads/pub/advances/vol2/Hunt.pdf on September 29, 2010. 

31 The Secretary of Health and Human Services (Secretary) delegated authority to AHRQ to 

make these determinations, as well as to fulfill other requirements of the Patient Safety Act. 

Patient Safety and Quality Improvement Act of 2005, P.L. 109-41 § 2, PHSA, § 924, 

42 U.S.C. § 299b-24; 73 Fed. Reg. 70732 (Nov. 21, 2008). 

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INTRODUCTION 

useful adverse event report.32 A variety of organizations are eligible to 

become PSOs, including hospital associations, hospital chains, and 

patient safety consulting groups.33 For a 2009 OIG study, staff from 

selected PSOs reported barriers that could limit hospital participation 

in PSOs and questioned the usefulness of submitting data for 

aggregation.34 Finally, the American Recovery and Reinvestment Act of 

2009 appropriated $300 million to AHRQ to sponsor and disseminate 

research that compares the effectiveness of clinical care options, the 

purpose of which is to promote evidence-based medical care.35 

In March 2010, Congress passed health care reform legislation in the 

form of the Patient Protection and Affordable Care Act (ACA).36 The 

ACA includes a number of provisions to take effect over multiple years, 

including expanded funding and authority to the Department of Health 

and Human Services (HHS) to address health care quality issues. 

Among the initial efforts to implement the ACA, the Secretary is to 

establish a national strategy for quality improvement in health care by 

January 1, 2011.37 The law requires that the strategy address eight 

national priority areas, one of which is to improve patient safety.38 It 

also increases funding to CQuIPS for research grants to explore best 

practices.39 Among its payment provisions, the ACA expands the 

Medicare HAC policy to mandate hospital payment penalties for high 

rates of HACs,40 create new quality measures,41 and require State 

Medicaid agencies to deny higher reimbursement for care associated 

with HACs.42 

32 AHRQ, Common Formats for Patient Safety Data Collection and Event Reporting, Notice 

of Availability: Common Formats Version 1.0, September 2, 2009. Accessed at 

http://www.pso.ahrq.gov/formats/commonfmtv1_0fr.htm on October 12, 2010. 

33 PHSA, § 924(b), 42 U.S.C. § 299b-24(b). 

34 OIG, Adverse Events in Hospitals: Public Disclosure of Information About Events, 

OEI-06-09-00360, January 2010. 

35 American Recovery and Reinvestment Act of 2009, P.L. 111-5, Division A, Title VIII. 

36 ACA, P.L. 111-148, was signed into law on March 23, 2010, after we had completed data 

collection and analysis for this study. 

37 P.L. 111-148 § 3011, PHSA, § 399HH, 42 U.S.C. § 280j. 

38 P.L. 111-148 § 3011, PHSA, § 399HH(a)(2)(B)(vii), 42 U.S.C. § 280j(a)(2)(B)(vii). 

39 P.L. 111-148 § 3501, PHSA, §§ 933 and 934. 

40 P.L. 111-148 § 3008(a), SSA, § 1886(p), 42 U.S.C. § 1395ww(p). 

41 P.L. 111-148 § 3013 inserted new section 931 of the PHSA, 42 U.S.C. § 299b-31, and 

added section 1890A(e) of the SSA, 42 U.S.C. § 1395aaa-1(e). 

42 P.L. 111-148 § 2702. 

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INTRODUCTION 

METHODOLOGY 

Scope 

This report estimates the national incidence of adverse events based on 

a representative sample of Medicare beneficiaries discharged from 

inpatient acute care hospitals during October 2008. Our results are 

projectable to all Medicare beneficiaries hospitalized during this period 

nationwide. To determine the estimated rate of adverse events, we used 

criteria developed by NQF, CMS, and NCC MERP. We included in the 

estimated national incidence rate all patient harm that occurred during 

the hospital stay, regardless of whether it was preventable. Also, the 

report provides a physician assessment of the extent to which identified 

events were preventable and analysis of billing data to estimate the cost 

to the Medicare program for increased reimbursement resulting from all 

events and preventable events. 

Sample Selection 

We selected a sample of Medicare beneficiaries from the National 

Claims History (NCH). Of the 999,645 beneficiaries discharged from 

acute care hospitals during October 2008, we selected a random sample 

of 785 beneficiaries. We excluded 5 beneficiaries as ineligible because 

the hospital was currently under OIG investigation, resulting in a 

sample of 780 beneficiaries. In July–October 2009, we requested and 

received medical records from hospitals regarding sample beneficiaries’ 

hospital stays. Fifty-four of the beneficiaries had more than 1 hospital 

stay during October (50 had 2 stays and 4 had 3 stays). Combined, 

sample beneficiaries had 838 hospital stays with discharges in 

October 2008 and an average length of stay of 5.2 days.43 

Identifying Adverse Events and Determining Preventability 

We conducted a two-stage review to identify adverse events experienced 

by each beneficiary. The first stage used three screening methods to 

identify cases likely to include an event. This enabled us to reduce the 

number of cases requiring the second-stage physician review. During 

the first stage, we identified cases that met one or more of the following 

conditions: (1) certified medical coders identified codes in the Medicare 

claims data that were listed as not present on admission, (2) nurse 

reviewers found evidence of a potential adverse event in the medical 

43 The average length of stay for hospitalized Medicare beneficiaries overall in 2007 was 

5.6 days. CMS, 2009 CMS Statistics, Table IV.1 Medicare Short-stay Hospital Utilization, 

2009, Tab 1. 

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INTRODUCTION 

records, or (3) the beneficiary had a hospital admission within 30 days 

after discharge for his or her last sample hospital stay ending in 

October 2008.44 

We identified 420 cases for the second stage of review, which entailed a 

review of the full medical records by physicians to identify events. To 

ensure consistency across physician reviewers, we facilitated weekly 

conference calls during which all physician reviewers discussed cases 

that either were complex or had possible implications for other cases. 

We included events experienced by patients during hospital stays or 

during prior, contiguous outpatient visits (wherein patients were 

transferred directly from outpatient care to inpatient care within the 

same facility). For example, we included in our count an adverse event 

that occurred in a hospital emergency department immediately 

preceding admission to inpatient care. We did not include events that 

occurred prior to a beneficiary’s arrival on the hospital campus. When 

an initial event caused a series of related events for the same patient, 

we collapsed the events into a “cascade event,” which counted as a 

single event.45 For a glossary of selected clinical terms used to describe 

events, see Appendix D. 

As part of the structured protocol, physician reviewers also determined 

the extent to which the identified events were preventable. Generally 

speaking, physicians assessed events as preventable when they 

determined that harm could have been avoided through improved 

assessments or alternative actions. Physicians assessed an event as not 

preventable when they determined that harm could not have been 

avoided given the complexity of the patient’s condition or the care 

required. The physician protocol used the following response scale for 

assessing the preventability of events: clearly preventable, likely 

preventable, clearly not preventable, likely not preventable, and unable 

to determine. Physicians used their clinical experience and judgment to 

make preventability determinations. They considered all evidence in 

44 We reviewed records for admissions that occurred within 30 days of the last beneficiary 

discharge. Therefore, the 30-day window for reviewing readmissions did not span a fixed 

timeframe but began on the unique final discharge date for each beneficiary with the last 

possible admission occurring on November 30, 2008 (30 days following the final possible 

October 31, 2008, discharge). 

45 Based on OIG interviews with IHI staff, IHI defines a cascade event as one in which an 

initial event causes a series of related events for the same patient and advocates collapsing 

these into a single event. 

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INTRODUCTION 

the medical records, including the actions of hospital and medical staff 

and the patient’s condition. Assessing an event as clearly preventable 

or clearly not preventable required a greater degree of certainty on the 

part of the reviewer. For detailed information about the methodology 

for identifying events and determining preventability, see Appendix E. 

Data Analysis 

We performed analysis and generated estimates about adverse events 

for three categories: incidence of events, preventability of events, and 

Medicare cost associated with events. We also calculated separate 

estimates regarding these categories for temporary harm events. For 

estimates and corresponding 95-percent confidence intervals for all 

statistical analyses, see Appendix F. 

Adverse event incidence analysis. We calculated the estimated national 

adverse event incidence rate as the percentage of Medicare beneficiaries 

with at least one adverse event. We defined adverse events as events 

that met at least one of the following criteria: 

1. the event was on the NQF list of Serious Reportable Events, as the 

Act mandates; 

2. the event was on Medicare’s list of HACs for which it denies higher 

payment; or 

3. the event resulted in one of the four most serious categories on the 

NCC MERP index (classified on the index as F-I): 

- prolonged hospital stay, 

- permanent harm, 

- life-sustaining intervention, or 

- death. 

We also calculated individual rates for adverse events on the NQF list, 

the Medicare HAC list, and events classified as F-I on the NCC MERP 

index. The overall adverse event incidence rate does not include events 

that physician reviewers identified as temporary harm events, defined 

as events that required intervention but did not cause lasting harm 

(classified as E level harm on the NCC MERP index). We excluded 

these temporary harm events from our overall rate because we 

determined, in consultation with physician reviewers, that the effect of 

these events was not comparable to the more serious events meeting the 

three criteria. We calculated a separate incidence rate for beneficiaries 

who experienced only temporary harm events. We projected incidence 

rates to the population of Medicare beneficiaries discharged from 

inpatient acute care hospital stays during October 2008. 

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As an additional measure of adverse event rates, we calculated 2 ratios 

of adverse event incidence density: events per 1,000 patient days and 

events per 100 hospital admissions. These measures are commonly 

used by hospitals and medical researchers.46 For the resulting metrics 

and an explanation of the calculation method, see Appendix G. 

Preventability analysis. The findings related to preventability are based 

on determinations made by the physician reviewers for each adverse 

event and temporary harm event. We calculated percentages for each 

preventability classification and for different types of events, the results 

of which are projectable to the population. We also conducted statistical 

tests to identify differences in preventability rates between adverse 

events and temporary harm events and across various categories of 

adverse events, such as medication-related and infection-related events. 

Medicare cost analysis. We estimated the cost to Medicare resulting 

from care associated with adverse events and temporary harm events. 

This analysis included only Medicare claims that were paid under the 

IPPS and were subject to the Medicare HAC policy (84 percent of 

sample beneficiaries). Certified medical coders reviewed the medical 

records, the medical review protocols, and the associated Medicare 

claims to identify diagnosis and procedure codes that would not have 

been included in the claims if the events had not occurred. We then 

used CMS’s MS-DRG Grouper and Medicare Code Editor Version 27 

(Grouper) to determine the DRG for the claims and used the FY 2009 

IPPS personal computer Pricer (Pricer) to determine the resulting 

Medicare reimbursement amounts. For each claim, we calculated the 

DRG and reimbursement amount, including information from the 

47

48

46 K.M. Arias, Outbreak Investigation, Prevention, and Control in Health Care Settings, 

Second Edition, Jones and Bartlett Publishers, 2009, pp. 330–331. 

47 The cost analysis does not include claims for beneficiaries whose Medicare coverage is 

not paid under the IPPS. This includes Medicare managed care organizations and care 

provided at hospitals excluded from the Medicare IPPS system, including hospitals in the 

State of Maryland and some specialty hospitals nationwide, such as cancer treatment centers 

and critical access hospitals. CMS, HAC Fact Sheet. Accessed at 

http://www.cms.gov/HospitalAcqCond/Downloads/HACFactsheet.pdf on September 29, 2010. 

48 The Grouper software classifies hospital claims into MS-DRG categories expected to 

have similar hospital resource requirements. MS-DRGs are based on the nine diagnoses 

associated with HACs and corresponding POA indicators, six procedure codes, and 

demographic data contained in the NCHs. MS-DRGs typically split into two or three 

individual classes based on the presence of a complication or comorbidity. This software was 

developed by CMS and 3M and is sold by the National Technical Information Service. 

Accessed at http://www.ntis.gov on September 29, 2010. 

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INTRODUCTION 

hospital Medicare claim. We then calculated the reimbursement 

amount excluding diagnosis and procedure codes that coders 

determined were the direct result of any adverse event or temporary 

harm event experienced by the beneficiary. We projected the difference 

between the two hospital reimbursement amounts to estimate the 

additional cost to Medicare for care associated with events. When an 

entire hospital stay was the result of an adverse event, we included the 

total reimbursement amounts indicated by the Pricer as the cost of the 

adverse event. 

Limitations 

Beyond the challenges associated with identifying adverse events and 

assessing preventability, the methodology presents two specific

limitations. First, it is unlikely that the study identified all adverse and 

temporary harm events within the sample. To the extent that the study 

did not identify an event, it was likely because the three screening 

methods failed to flag the case for physician review or because 

documentation in the medical records was incomplete. Second, cost 

estimates did not include all costs of care associated with events, 

excluding stays not covered under the Medicare IPPS, additional 

hospital stays caused by sample events but occurring after 

October 2008, additional care outside the hospital (such as followup 

physician office visits or rehabilitation services), and changes in 

Medicare outlier payments.49 

Standards 

This study was conducted in accordance with the Quality Standards for 

Inspections approved by the Council of the Inspectors General on 

Integrity and Efficiency.

49 Medicare outlier payments are supplemental payments to hospitals for patients who 

incur extraordinarily high costs. Outlier payments are based on the degree to which costs on a 

claim exceed specific hospital and MS-DRG fixed-loss thresholds and fluctuate depending on 

the MS-DRG to which the claim is grouped. The Pricer analysis involved a revision of the 

MS-DRG. This revision resulted in new outlier payments for three sample cases and 

increased outlier payments for two sample cases. The revised outlier payments decreased the 

cost attributed to adverse events in our estimate. 

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FINDINGS 

Of the nearly 1 million Medicare 

beneficiaries discharged from 

hospitals in October 2008, about 

1 in 7 experienced an adverse 

event (13.5 percent), defined as an event that met at least 1 of the 

following 3 criteria: the event was on the NQF list of Serious 

Reportable Events; the event was on Medicare’s list of HACs; or the 

event resulted in 1 of the 4 most serious categories on the NCC MERP 

index (prolonged hospital stay, permanent harm, life-sustaining 

intervention, or death). This incidence rate projects to approximately 

134,000 Medicare beneficiaries experiencing at least 1 adverse event in 

hospitals during the study period. Table 2 lists the incidence rate for 

each of the three criteria. 

An estimated 13.5 percent of hospitalized 

Medicare beneficiaries experienced adverse 

events during their hospital stays 

 FINDINGS 

Table 2: Estimated National Incidence of Adverse Events Among 

Medicare Beneficiaries Discharged in October 2008 

Category of Events 

Estimated 

Percentage of 

Medicare 

Beneficiaries 

Estimated 

Number of 

Medicare 

Beneficiaries 

NQF Serious Reportable Events* 0.6% 6,367 

Medicare HACs* 1.0% 10,187 

NCC MERP F-I Level Events 13.1% 129,890 

(Overlap)** (1.3%) (12,734) 

 Total 13.5%*** 133,710 

See Appendix F for confidence intervals. 

*Given the small proportions, confidence intervals for projected numbers exceed 50-percent relative precision. 

**The 1.3 percent represents beneficiaries who experienced adverse events in more than one category. We 

counted these beneficiaries only once in determining the overall incidence rate. 

***Column does not sum to 13.5 percent because of rounding. 

Source: OIG analysis of hospital stays for 780 Medicare beneficiaries discharged in October 2008. 

We classified the identified adverse events into four clinical categories: 

events related to medication (31 percent), events related to ongoing 

patient care (28 percent), events related to surgery or other procedures 

(26 percent), and events related to infection (15 percent). Table 3 lists 

the 128 adverse events found in the sample within these categories. See 

Appendix H for a list of the events with more complete descriptions, the 

level of harm patients incurred, and indications of whether the events 

were on the NQF and HAC lists. 

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FINDINGS 

Table 3: Adverse Events Identified Among Sample Medicare 

Beneficiaries by Clinical Category (n=128)

Number of Events 

and Percentages of 

Total Events 

Types of Adverse Events 

Events Related to Medication 31% (40) 

 Excessive bleeding 12 

 Delirium or change in mental status 7 

 Hypoglycemic event 6 

 Acute renal insufficiency (kidney failure) 4 

 Severe hypotension 4 

 Respiratory complications 4 

 Severe allergic reactions 3 

Events Related to Patient Care 28% (36) 

 Intravenous volume overload 10 

 Aspiration 8 

 Deep vein thrombosis or pulmonary embolism 5 

 Exacerbation of preexisting medical condition 5 

 Stage III pressure ulcer 3 

 Breakdown of surgical wound 1 

 Congestive heart failure 1 

 Hypoxia (oxygen deficiency) 1 

 Patient fall with injury 1 

 Prolonged weakness and dizziness 1 

Events Related to Surgery or Other Procedures 26% (33) 

 Excessive bleeding 5 

 Severe hypotension 4 

 Respiratory complication 4 

 Iatrogenic pneumothorax 3 

 Postoperative ileus 3 

 Postoperative urinary retention 3 

 Acute coronary syndrome 2 

 Blood clot and other occlusion 2 

 Cardiac complication 2 

 Cardiac dysrhythmia 1 

 Delay in surgery because of equipment malfunction 1 

 Hemorrhage at surgical site 1 

 Seroma (fluid) following stomach resection 1 

 Urinary catheter-associated trauma 1 

Events Related to Infection 15% (19) 

 Urinary tract infection 5 

 Vascular catheter-associated infection (central or peripheral line) 4 

 Other bloodstream infection 4 

 Respiratory infection 4 

 Surgical or procedural site infection 2 

Of beneficiaries who experienced adverse events, 18 percent had 

more than one adverse event. Most of the beneficiaries who experienced 

multiple events had two events, but others had as many as three 

Source: OIG analysis of hospital stays for 780 Medicare beneficiaries in October 2008. 

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FINDINGS 

unrelated events in the same hospitalization. For example, an elderly 

heart patient with a history of mental illness experienced three adverse 

events of different types, including two events that prolonged 

hospitalization and a third that required life-sustaining intervention. 

(This beneficiary also experienced three temporary harm events 

associated with patient care.) 

Less than 1 percent of Medicare beneficiaries experienced an event on 

the NQF list of Serious Reportable Events 

An estimated 0.6 percent of Medicare beneficiaries experienced an event 

on the NQF list, which projects to approximately 6,400 beneficiaries 

nationally for the study period. The low number of NQF events in the 

sample is notable because of the prominence of the list as a measure of 

patient harm and its use by a number of State adverse event reporting 

systems and other entities. We identified a total of five NQF events in 

the sample: two medication-related deaths and three Stage III pressure 

ulcers.50 One of the medication-related deaths illustrates the nature of 

the NQF list as a measure of the most egregious preventable outcomes. 

In this case, a disabled Medicare beneficiary with muscular dystrophy 

affecting the respiratory system entered the hospital for signs of 

respiratory failure. Medical staff at the hospital gave the beneficiary a 

medication known to further suppress respiration, resulting in 

progressive respiratory distress and subsequent death. Physician 

reviewers concluded that medical staff administered the wrong 

medication because they lacked clinical understanding of the patient’s 

unique condition. 

Many serious events that we identified were not on the NQF list of 

Serious Reportable Events, including some events that resulted in 

patient deaths and serious disability. The NQF list focuses largely on 

serious disability or death, but is restricted to a specific set of events. 

Of the 18 adverse events that physician reviewers found to result in 

serious disability or patient death, only 2 were on the NQF list (i.e., the 

medication errors resulting in death). The three Stage III pressure 

ulcers identified in the sample were sufficiently treated prior to 

50 Pressure ulcers are classified into four stages by the National Pressure Ulcer Advisory 

Panel (NPUAP): Stage I is intact skin with nonblanchable redness; Stage II is a shallow ulcer 

or blister indicating damage to the epidermis; Stage III is damage extending through all the 

layers of the skin; and Stage IV is damage through all the layers of the skin and underlying 

muscle, tendons, or bone. NPUAP, Pressure Ulcer Stages Revised by NPUAP. Accessed at 

http://www.npuap.org on November 12, 2009. 

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FINDINGS 

discharge from the hospital and determined by physicians to have 

caused only temporary harm. 

Medicare HACs rarely occurred, affecting just 1 percent of beneficiaries 

An estimated 1 percent of hospitalized Medicare beneficiaries 

experienced Medicare HACs, which projects to approximately 10,000 

beneficiaries nationally. We identified a total of nine Medicare HACs 

experienced by beneficiaries in the sample: five catheter-associated 

urinary tract infections, two vascular catheter-associated infections of 

the central line, one patient fall resulting in injury (a compression 

fracture), and one Stage III pressure ulcer. One beneficiary experienced 

two of these events, resulting in a total of eight sample beneficiaries 

with Medicare HACs. Two catheter-associated urinary tract infections 

caused more substantial harm than is typically associated with this 

condition: one resulted in a prolonged hospital stay and the other in 

permanent harm. The two vascular catheter-associated infections of a 

central line resulted in prolonged hospital stays. None of the nine 

Medicare HACs identified by physicians on the medical records were 

included in the associated Medicare claims. In four of the nine cases (all 

catheter-associated urinary tract infections), diagnosis codes on the 

claims identified the infections, but they were not the precise codes that 

CMS uses to identify these HACs. The other five claims had no 

diagnosis codes related to the HACs. Therefore, the HACs were not 

identifiable through the claims data that CMS uses to implement the 

HAC policy. 

Thirteen percent of Medicare beneficiaries experienced adverse events 

classified in the most serious categories on the NCC MERP harm index 

Based on our physician medical review, 13.1 percent of Medicare 

beneficiaries experienced adverse events classified in the four most 

serious harm categories on the NCC MERP harm index: events 

resulting in prolonged hospital stay, events resulting in permanent 

harm, events requiring life-sustaining intervention, and events 

contributing to death. This rate projects nationally to approximately 

130,000 beneficiaries experiencing such adverse events during the study 

period. Often, adverse events within the same clinical category, such as 

infection, resulted in a different level of harm depending on the 

intervention required and the condition of the patient. Table 4 lists the 

percentage of adverse events in the sample that were classified in the 

four most serious harm categories and the projected national numbers 

of events by level of patient harm. 

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FINDINGS 

Table 4: Adverse Events Classified as F-I on the NCC MERP 

Patient Harm Index by Level of Harm 

Level of Harm Percentage of Adverse Events 

F level: Requiring prolonged hospital stay 62% 

G level: Permanent harm* 5% 

H level: Life-sustaining intervention required 23% 

I level: Contributing to death* 10% 

See Appendix F for confidence intervals. 

*Given the small proportions, confidence intervals for projected numbers exceed 50-percent relative precision. 

Source: OIG analysis of hospital stays for 780 Medicare beneficiaries discharged in October 2008. 

An estimated 1.5 percent of hospitalized Medicare beneficiaries 

experienced events that contributed to their deaths 

Among the 128 adverse events that we identified in the sample, 

12 events (9 percent of 128 events) contributed to the deaths of 

beneficiaries. This projects to an estimated 1.5 percent of hospitalized 

Medicare beneficiaries experiencing events that contributed to death or 

approximately 15,000 beneficiaries during the study period. Seven of 

the twelve deaths were related to medication, either the result of 

improper administration of medication (wrong drug or wrong dosage) or 

inadequate treatment of known side effects. The most common type of 

medication-related death (five deaths) involved excessive bleeding from 

blood-thinning medication. The two other medication-related deaths 

involved inadequate insulin management resulting in hypoglycemic 

coma and respiratory failure resulting from oversedation. Of the five 

non-medication-related deaths, two were from bloodstream infections; 

two involved aspiration (which led to pneumonia and cardiac arrest, 

respectively); and the other involved a ventilator-associated pneumonia. 

As stated previously, only 2 of the 12 adverse events that contributed to 

death were on the NQF list and none were Medicare HACs. 

Twenty-seven percent of beneficiaries who experienced adverse events had 

at least one “cascade” event, wherein multiple, related events occurred in 

succession 

The sample included a total of 28 cascade events, defined as adverse 

events that included a series of multiple, related events. We counted 

these as single events. These cascade events were some of the most 

serious adverse events identified in the sample, with nine cases 

requiring life-sustaining intervention and six cases contributing to 

death. The most common type of cascade events were events related to 

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FINDINGS 

surgery and other procedures (nine events). Two of these events began 

with excessive bleeding following surgery or a procedure. For example, 

one beneficiary had excessive bleeding after his kidney dialysis needle 

was inadvertently removed, which resulted in circulatory shock, a 

transfer to the intensive care unit, and emergency insertion of a tube 

into the trachea (windpipe) to ease breathing. When the tube was 

removed the following day, the patient aspirated (inhaled foreign 

material into his lungs), which required a life-sustaining intervention. 

An additional 13.5 percent of Medicare 

beneficiaries experienced events during their 

hospital stays that resulted in temporary harm 

An additional 13.5 percent of 

Medicare beneficiaries 

experienced events during the 

study period classified as E level 

harm on the NCC MERP index, defined as events that required medical 

intervention but did not cause lasting harm. This rate projects to 

approximately 134,000 Medicare beneficiaries experiencing temporary 

harm events during the study period. Of these beneficiaries, 22 percent 

had more than one unrelated event (the highest occurrence was five 

unrelated events in a single hospital stay). Additionally, 28 percent of 

beneficiaries who experienced adverse events (and are included in our 

primary rate) also had temporary harm events during the same stay. 

Events classified as temporary harm represented a wide array of 

conditions, such as prolonged vomiting and hypoglycemia (see Table 5). 

The most common events related to medication (42 percent). Although 

many cases of temporary harm represented fairly minor occurrences, we 

classified others as temporary because the patients were in the hospital 

for a lengthy period because of other, more serious, diagnoses, allowing 

the hospital enough time to address the harm prior to discharge. 

Physician reviewers indicated that many temporary harm events could 

have developed into more serious adverse events, but hospitals provided 

timely intervention. For example, Stage I or Stage II pressure ulcers 

can escalate quickly to Stage III or Stage IV without proper care51 and 

episodes of hypoglycemia can lead to stroke and even death.52 

51 J.L. Zeller, C. Lynm, and R.M. Glass, Pressure Ulcers, Journal of the AMA, 296(8), 

August 23/30, 2006, p. 1020. Accessed at http://jama.ama-assn.org on December 1, 2009. 

52 P. Mandava and T. Kent, Metabolic Disease & Stroke: Hyperglycemia/Hypoglycemia, 

Journal of Diabetes Science and Technology, 17, April 4, 2006, p. 8. Accessed at 

http://emedicine.medscape.com on December 1, 2009. 

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FINDINGS 

Table H-2 in Appendix H contains a list of the 174 temporary harm 

events identified in the sample with more complete descriptions. 

Table 5: Temporary Harm Events Identified Among Sample 

Medicare Beneficiaries by Clinical Category (n=174)

Number of Events and 

Percentage of Total 

Events 

Types of Temporary Harm Events 

Events Related to Medication 42% (73) 

 Delirium or change in mental status 22 

 Hypoglycemic event 11 

 Thrush and other opportunistic infection 7 

 Allergic reaction or side effect related to skin 6 

 Gastrointestinal complication 5 

 Hypotension 5 

 Dysrhythmia 3 

 Excessive bleeding 3 

 Severe headache or dizziness 3 

 Acute renal failure or insufficiency 2 

 Allergic reaction to blood or related products 2 

 Respiratory complication 2 

 Other events related to medication 2 

Events Related to Patient Care 36% (63) 

 Stage I, Stage II, or unstaged pressure ulcer 20 

 Intravenous volume overload 15 

 Skin tear, laceration, abrasion, or other breakdown 9 

 Intravenous infiltrate with symptoms 6 

 Patient fall with injury 5 

 Aspiration 3 

 Failure to treat constipation or obstipation 3 

 Tachycardia or dysrhythmia 2 

Events Related to Surgery or Other Procedures 18% (32) 

 Urinary retention 8 

 Excessive bleeding 6 

 Cardiac complication 4 

 Surgical tear or laceration 3 

 Urinary catheter-related trauma 3 

 Prolonged nausea and vomiting 2 

 Postoperative or postprocedural hypotension 2 

 Respiratory complication 2 

 Other events related to surgery or other procedures 2 

Events Related to Infection 4% (6) 

 Surgical site infection 2 

 Bacterial infection 1 

 Respiratory infection 1 

 Urinary tract infection 1 

 Vascular catheter-associated infection 1 

Source: OIG analysis of hospital stays for 780 Medicare beneficiaries in October 2008. 

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FINDINGS 

Physician reviewers determined that 

44 percent of adverse events and temporary 

harm events were clearly or likely preventable 

Physician reviewers assessed the 

extent to which events were 

preventable based on information 

in the medical records, their 

clinical experience with similar circumstances, research literature about 

the preventability of specific events, and group discussion to reach 

consensus. Combining adverse events and temporary harm events, 

physicians determined that 44 percent were preventable and 51 percent 

were not preventable.53 (There was no statistically significant 

difference between the preventability rates of adverse events and 

temporary harm events.)54 For the remaining 5 percent of events, 

physicians were unable to make determinations because of incomplete 

documentation in the medical records or extreme complexities in the 

patients’ conditions or in the hospital care provided. Table 6 provides 

the percentage of events by the physician preventability assessment. 

Table 6: Events by Physician Preventability Assessment

Preventability Assessment Percentage of Events 

Preventable—Harm could have been avoided through 

improved assessment or alternative actions 44%

Clearly preventable 9%

Likely preventable 35%

Not preventable—Harm could not have been avoided given 

the complexity of the patient’s condition or care required 51%

Clearly not preventable 18%

Likely not preventable 33%

Unable To Determine Preventability 5%

Source: OIG analysis of hospital stays for 780 Medicare beneficiaries discharged in October 2008. 

Physician reviewers assessed the preventability of events similarly for 

three of the four clinical categories (medication, patient care, and 

infections). However, events related to surgery and other procedures 

were significantly less likely to be determined preventable than events in 

the other three clinical categories; only 17 percent of surgical events were 

53 The preventability rate of 44 percent is similar to the rate of 43.5 percent found by a 

2008 review of 8 adverse event preventability studies previously referenced on p. 7. 

54 The Cochran-Mantel-Haenszel chi square test was not significant at the 95-percent 

confidence level (p=0.0568). See Appendix F for detailed preventability statistics for adverse 

events and temporary harm events. 

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FINDINGS 

preventable in contrast to 50 percent or more in each of the other three 

groups.55 Physician reviewers indicated that the reasons surgical events 

were more likely to be assessed as not preventable were the high level of 

complexity in both the care involved and the patients’ conditions. Table 7 

provides the percentage of preventable events by clinical category. 

Table 7: Preventable Events Within Clinical Categories 

Clinical Category Percentage of Events 

Assessed as Preventable 

Infection 60% 

Medication 50% 

Patient care 51% 

Surgery and other procedures 17% 

Source: OIG analysis of hospital stays for 780 Medicare beneficiaries discharged in October 2008. 

Within the clinical categories, physician reviewers sometimes gave the 

same preventability assessment for events with similar characteristics. 

For example, they assessed 10 of 12 events related to allergic reactions 

as not preventable. But for other types of events, preventability 

determinations for similar events differed based on the patients’ 

conditions and risk factors. For example, in two cases of excessive 

stomach bleeding caused by blood thinners, physicians assessed one 

event affecting a relatively healthy patient as preventable and the other 

event affecting a patient with stomach ulcers as not preventable 

because of the patient’s susceptibility. In another case, physician 

reviewers determined that some pressure ulcers were not preventable 

because of the poor conditions of the patients and because 

documentation in the medical records showed that the hospital staff 

employed appropriate preventive care. However, physicians assessed 

another pressure ulcer case as preventable because the medical staff 

declined to order a specialty mattress for an at-risk bedridden patient 

until after the pressure ulcer had developed, even though the medical 

record indicated that the specialty bed was available. 

 

55 The Cochran-Mantel-Haenszel chi square test was significant at the 95-percent 

confidence level for the overall relationship between preventability and clinical category 

(p<0.0001) as well as for each set of pair-wise comparisons between the surgical category and 

each of the other three clinical categories (p<0.01 for each pair). Preventability rates were 

62 percent for infections, 50 percent for medication, and 50 percent for patient care. 

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FINDINGS 

Counting only preventable events, the estimated national incidence rate of 

adverse events among Medicare beneficiaries would be 7.4 percent 

The estimated adverse event incidence rate of 13.5 percent is based on 

all adverse events’ meeting one of the three criteria, regardless of 

whether the events were preventable. Including only the adverse 

events determined by physician reviewers to be clearly or likely 

preventable, the estimated incidence rate of adverse events among 

Medicare beneficiaries would be 7.4 percent. The 13.5 percent rate of 

additional beneficiaries experiencing temporary harm events would be 

6.3 percent if only preventable events were included. 

Eleven of the thirteen NQF Serious Reportable Events and Medicare HACs 

in the sample were preventable, a key criterion of both lists 

Although we found few in the sample, all but two adverse events on the 

NQF and HAC lists were assessed as clearly or likely preventable.56 

After the adverse events on each list were separated, four of the five 

events on the NQF list were preventable and eight of the nine Medicare 

HACs were preventable (one event was on both lists). A key criterion of 

both lists is that the events be largely preventable. The two events on 

the lists that physicians assessed as not preventable were (1) an NQF 

event consisting of a pressure ulcer that progressed from Stage I to 

Stage III in a chronically ill patient with multiple complications and 

susceptibility to skin breakdown and (2) a Medicare HAC consisting of a 

compression fracture incurred during a fall by a morbidly obese patient.

Preventable events were most commonly linked to medical errors, 

substandard treatment, and inadequate patient monitoring or assessment 

Physician reviewers selected one or more rationales to support each 

preventability determination from a list developed by the physician 

panel. To develop these rationales, physicians gleaned information from 

medical records, such as clinical staff actions, hospital environmental 

factors, and patient condition unrelated to the event. Among events 

assessed as preventable, 58 percent were linked to errors by clinical 

staff in medical judgment, skill, or patient management. Such errors 

often involved prescribing or administering the wrong medication. 

Nearly half of preventable events (46 percent) involved care provided in 

a substandard way, most frequently because of delay in diagnosis or 

56 The number of NQF and HAC events was too small to test the preventability measure for 

statistical significance with an acceptable degree of precision or to project the measure to the 

national sampling frame. 

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FINDINGS 

treatment. Table 8 provides physician preventability rationales for 

events within each assessment category. 

Table 8: Events by Physician Preventability Rationales 

Percentage 

of Events* Preventability Rationale 

Preventable Events (n=133) 

Error was related to medical judgment, skill, or patient management 58% 

Appropriate treatment was provided in a substandard way 46% 

The patient’s progress was not adequately monitored 38% 

The patient’s health status was not adequately assessed 23%

Necessary treatment was not provided 17% 

Event rarely happens when proper precautions and procedures are followed** 14% 

Communication between caregivers was poor** 8% 

Facility’s patient safety systems and policies were inadequate or flawed** 3% 

Breakdown in hospital environment occurred (equipment failure, etc.)** 2% 

Nonpreventable Events (n=155)

Event occurred despite proper assessment and procedures followed 62% 

Patient was highly susceptible to event because of health status 50% 

Care provider could not have anticipated event given information available 35% 

Patient’s diagnosis was unusual or complex, making care difficult 29% 

Harm was anticipated but risk considered acceptable given alternatives** 14% 

See Appendix F for confidence intervals. 

*Percentages do not add to 100 because physician reviewers often selected more than 1 rationale. 

**Given the small percentages, confidence intervals for projected numbers exceed 50-percent relative precision. 

Source: OIG analysis of hospital stays for 780 Medicare beneficiaries discharged in October 2008. 

Other common factors associated with preventable events were 

inadequate monitoring of patients (38 percent) and inadequate 

assessment of patients (23 percent). These factors often led to delays in 

treatment and worsening of patient conditions. In several of these 

cases, patients displayed symptoms of infection but were not given 

antibiotics until they reached the point of sepsis. In one case, the 

patient exhibited signs of shock upon arrival at the hospital, but clinical 

staff did not monitor the patient’s blood pressure for the first 8 hours 

and did not provide related treatment for another 16 hours. This delay 

caused the patient to experience severe hypotension, requiring 

life-sustaining intervention. 

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FINDINGS 

Physician reviewers assessed events as clearly or likely not preventable 

when the events occurred despite proper procedures or when the 

patients were highly susceptible to the events 

For 62 percent of the nonpreventable events in our sample, physician 

reviewers found that care was rendered according to accepted standards 

of practice. In these cases, physicians determined that the care 

provided was sufficient and appropriate and that there was no evidence 

of errors or other problems. This rationale was often given in 

combination with the second most common factor—that the patients’ 

other conditions made them highly susceptible to the event (50 percent 

of nonpreventable events). For example, one beneficiary, admitted to 

the hospital with a bowel obstruction, experienced a surgical cut of the 

intestine that would have been difficult to avoid because of significant 

damage to the bowel from prior surgery. 

Other common rationales for assessing events as not preventable also 

focused on the difficulty of providing care. For 35 percent of 

nonpreventable events, physicians determined that the medical and 

hospital staff could not have anticipated the events given information 

available about the patients at the time of care delivery. For 29 percent 

of nonpreventable events, physicians determined that the patients’ 

diagnoses were unusual or complex, making care particularly difficult. 

Finally, in 14 percent of nonpreventable cases, the adverse events were 

anticipated by caregivers, but the harm associated with the adverse 

events was considered less harmful than not providing care. For 

example, in four sample cases, patients experienced harm as a result of 

an overload of intravenous fluid, yet the medical review found that the 

patients were in such dire need of fluids (e.g., at risk for hypoglycemic 

shock) that caregivers had little choice but to execute vigorous 

intravenous fluid replacement despite the risk of overload. 

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FINDINGS 

Hospital care associated with adverse events 

and temporary harm events cost Medicare an 

estimated $324 million in October 2008 

Sixteen percent of sample 

beneficiaries under the Medicare 

IPPS who experienced events 

incurred additional Medicare 

hospital costs as a result. Most of the additional costs (87 percent) 

resulted from care associated with adverse events, with temporary 

harm events generating the remaining costs.57 These additional costs 

project to an estimated $324 million, which equates to 3.5 percent of the 

$9.2 billion that Medicare spent for inpatient care during 

October 2008.58 To give these figures an annual context, 3.5 percent of 

the $137 billion Medicare inpatient expenditure in FY 2009 equates to 

$4.4 billion spent on care associated with adverse events.59 

Costs associated with preventable events accounted for an estimated 

$119 million of the $324 million additional cost, equating to 1.3 percent 

of the $9.2 billion Medicare inpatient expenditures for the month or 

about $1.8 billion annually. 

Despite this outlay, most events did not affect Medicare costs; none of 

the Medicare HACs resulted in a higher reimbursement 

Of beneficiaries who experienced adverse events or temporary harm 

events in hospitals covered under the Medicare IPPS, 84 percent did not 

incur additional costs for care associated with the events. This occurred 

primarily because many Medicare claims for beneficiaries who 

experienced events did not include diagnosis or procedure codes relating 

to the events. When Medicare claims included codes associated with the 

events, the codes often had no effect on costs because the claims 

included other costly diagnoses or procedure codes that elevated the 

reimbursement to equivalent or higher amounts. 

57 One Medicare claim included codes for two events—one adverse event and one temporary 

harm event—and incurred an identical payment impact. This claim overlaps both groups and 

consequently the percentages do not total 100 percent: 87 percent of costs resulted from care 

associated with adverse events and 15 percent of costs resulted from care associated with 

temporary harm events. 

58 These cost estimates include only claims under the IPPS, representing 708 sample 

Medicare claims (85 percent), but do not include costs for the remaining 130 sample 

beneficiaries (15 percent) who had sample admissions not covered under IPPS. 

59 The annual cost estimate of $4.4 billion is 3.5 percent of the $137 billion Medicare 

inpatient costs for FY 2009, which assumes the same proportion of costs for adverse events for 

the other 11 months that we found in October 2008. Annual Medicare inpatient cost figures 

are from CMS, 2009 CMS Statistics Book, Table III.6, Office of Research, Development, and 

Information, CMS Pub. No. 03497, December 2009, p. 30. 

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FINDINGS 

None of the nine Medicare HACs identified in the sample resulted in a 

higher level of Medicare reimbursement. Although the Medicare HAC 

policy is intended to limit costs associated with the specified events, our 

review showed that none of the HACs in the sample would have invoked 

a higher Medicare reimbursement. None of the associated Medicare 

claims included the specific diagnosis codes that CMS uses to identify 

HACs. However, even if the codes had been included on the claims, the 

HAC policy would still not have resulted in payment reductions for 

these cases because other diagnosis or procedure codes would have 

elevated the reimbursement to a higher amount. 

Two-thirds of Medicare costs associated with events were the result of 

additional hospital stays necessitated by harm from events 

Sixty-five percent of the additional costs to Medicare ($210 million of 

the $324 million) were the result of entire, additional hospital stays 

required to treat the harm resulting from the adverse events. In some 

of these cases, the events occurred during outpatient services at the 

hospital (such as an emergency room visit or an outpatient surgery) and 

necessitated unplanned admissions to the inpatient facilities. In other 

cases, the events occurred during inpatient care and the beneficiaries 

were released from the hospital, but the aftereffects of the events 

necessitated subsequent hospital stays within the study period. The 

average Medicare cost of these additional hospital stays for sample 

beneficiaries was $13,745, compared with an average additional cost of 

$5,601 for event-related care that hospitals provided during the initial 

hospital stay in situations that did not necessitate additional stays.60, 61 

Medicare cost estimates do not include additional costs required for 

followup care after the sample hospitalization 

Because our cost analysis included only hospital stays that ended 

during October 2008, Medicare costs associated with care resulting from 

adverse events and temporary harm events are greater than our 

estimate. Beneficiaries may have had additional event-related hospital 

stays beyond our study period and may have incurred expenses to 

Medicare or personal expenses for followup care not reflected in 

inpatient claims, such as physician office visits, medication, and 

rehabilitation services during and after our study period. 

60 Averages reflect only costs greater than zero. 

61 The Student’s T-test comparing difference of means was significant at the 95-percent 

confidence level (p=0.0104). 

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FINDINGS 

As an example of an event resulting in subsequent Medicare costs not 

captured by our cost analysis, one sample beneficiary was initially 

admitted to the hospital in mid-October 2008 for a stroke. During this 

hospital stay, he experienced an allergic reaction to medication and was 

discharged with no additional cost associated with the event. However, 

following discharge, the allergic reaction progressed to a 

life-threatening condition known as Stevens-Johnson Syndrome.62 The 

beneficiary returned to the hospital during October for treatment, 

incurring the cost of an entire hospital stay as a result of the event, but 

was misdiagnosed and again discharged. The patient then incurred two 

additional hospital stays within the next 30 days to correctly diagnose 

and treat the condition. The total estimated inpatient cost to Medicare 

for the latter three hospital stays was $43,050, all necessitated by the 

event. Only $10,982 of this amount was incurred during the study 

period and included in our cost estimate. Physician reviewers 

determined that the medication-related event was preventable because 

the medication was known to be highly reactive and the condition was 

not diagnosed correctly, delaying treatment. 

62 This condition typically begins with a skin rash and fever and, if untreated, progresses to 

an array of conditions constituting serious harm, such as lung damage and renal failure. 

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 RECOMMENDATIONS 

In the decade since the IOM report, the need to improve patient safety 

has received much attention from Federal and State governments, 

advocacy groups, and the health care industry. Despite this attention, 

we found that 13.5 percent of Medicare beneficiaries experienced 

adverse events during their hospital stays in October 2008, most of 

which resulted in prolonged hospital stays, permanent harm, 

life-sustaining interventions, or death. An additional 13.5 percent of 

beneficiaries experienced temporary harm as the result of events. 

Physician reviewers determined that 44 percent of events were 

preventable and that preventable events often involved medical errors, 

substandard care, and inadequate monitoring or assessment of patients. 

We found that in addition to causing the harm to patients, adverse 

events and temporary harm events increased costs to Medicare by an 

estimated $324 million in a single month, or 3.5 percent of Medicare 

inpatient expenditures, suggesting potential savings from reducing the 

incidence of events. 

As the Federal Government’s principal agency for protecting the health 

of Americans,63 HHS is uniquely positioned to lead national efforts to 

reduce adverse events in hospitals. As part of the national strategy to 

improve health care quality mandated by the ACA, HHS is to “identify 

areas in the delivery of health care services that have the potential for 

rapid improvement in the quality and efficiency of patient care.”64 

Because many adverse events that we identified were preventable, our 

study confirms the need and opportunity for hospitals to significantly 

reduce the incidence of events. A number of agencies within HHS share 

responsibility for addressing this issue, most prominently AHRQ as a 

coordinating body for efforts to improve health care quality and CMS as 

the Nation’s largest health care payer and an oversight entity. 

Therefore, we recommend the following: 

AHRQ and CMS should broaden patient safety efforts to include all 

types of adverse events 

Efforts to improve patient safety often focus on a small subset of 

events that harm hospital patients. For example, NQF Serious 

Reportable Events or Medicare HACs represented only a fraction of 

63 HHS, HHS Agency Mission Statement, updated February 2004. Accessed at 

http://www.hhs.gov/about/ on March 23, 2010. 

64 P.L. 111-148 § 3501. 

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RECOMMENDATIONS 

the adverse events we identified in this report. Additionally, 

patient safety provisions in the ACA often refer specifically to 

reducing medical errors, rather than to the broader range of adverse 

events. AHRQ and CMS should avoid focusing patient safety efforts 

too narrowly on a small list of specific events, possibly failing to 

address the wider array of events that lead to most instances of 

patient harm. Rather, AHRQ and CMS should promote a definition of 

adverse events that more fully encompasses harm resulting from 

medical care. This broader definition would apply to a number of 

patient safety activities, including setting priorities for research, 

establishing guidelines for hospital reporting of events, developing 

prevention strategies, measuring health care quality, and 

determining payment policies. 

AHRQ and CMS should enhance efforts to identify adverse events 

Identifying adverse events assists policymakers and clinical researchers 

in directing prevention resources to the areas of greatest need, setting 

clear goals for improvement, assessing the effectiveness of specific 

strategies, holding hospitals accountable, and gauging progress in 

reducing incidence. 

 AHRQ should sponsor periodic, ongoing measurement of the 

incidence of adverse events. To facilitate measurement, AHRQ 

should establish a standard protocol for identifying events and 

analyzing information about incidence and causes. AHRQ should 

also consider providing hospitals with methods for measuring their 

incidence of events, goals for incidence reduction, and benchmarks 

or other means for comparing rates among providers. 

 AHRQ should continue to encourage hospitals to report to PSOs. 

Hospital reporting of adverse event information to PSOs can provide 

AHRQ with aggregated data about the nature and causes of events. 

To maximize the usefulness of PSO-reported data for national 

measurement and analysis, AHRQ should continue working toward 

establishing standard adverse event definitions and reporting 

formats and encouraging hospital reporting. 

 CMS should use POA indicators in hospital billing data to calculate 

the frequency of adverse events occurring within hospitals. These 

POA indicator data represent a rich source of information for 

identifying certain adverse events in claims data. CMS should 

establish routine methods for using POA indicators to guide patient 

safety improvement efforts. For example, CMS could direct that 

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RECOMMENDATIONS 

QIOs use POA indicators to monitor hospital rates of specific 

conditions. 

CMS should provide further incentives for hospitals to reduce the 

incidence of adverse events through its payment and oversight functions 

CMS, as both a payer and an oversight entity, is positioned to influence 

hospitals to provide high-quality care. CMS should explore avenues to 

reduce the incidence of adverse events through both program 

participation and payment policy. 

 CMS should strengthen the Medicare HAC policy. We found that 

HACs represent a small proportion of preventable events and that 

they are not always coded as such in Medicare claims. The ACA 

makes several changes to the HAC policy, including allowing the 

Secretary to expand the list of HACs. The law also gives the HAC 

policy greater significance by using the list of HACs to implement 

Medicare payment penalties, create performance measures, and 

prohibit Medicaid payments for associated care. Given their low 

incidence, continued use of the 10 HACs already established by CMS 

may limit the intended effect of the statute. To strengthen the 

policy, CMS should consider expanding the list of Medicare HACs to 

include more conditions that may result in harm to beneficiaries. 

CMS should also take additional steps to ensure that hospitals 

accurately code Medicare claims to show when HACs occur, as 

recommended in our prior report.65 

 CMS should look for opportunities to hold hospitals accountable for 

adoption of evidence-based practice guidelines. The conditions of 

participation for Medicare and Medicaid require that hospitals have 

programs to demonstrate quality improvement where evidence 

shows practices can improve outcomes. CMS should further 

influence hospitals to reduce adverse events through enforcement of 

the conditions of participation. This could include more closely 

examining patient safety issues through the survey and certification 

process, as recommended in our prior report.66 This could also 

include encouraging hospitals to adopt evidence-based practices 

shown to prevent adverse events. 

65 OIG, Adverse Events in Hospitals: Methods for Identifying Events, OEI-06-08-00221, 

March 2010. 

66 Ibid. 

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RECOMMENDATIONS 

AGENCY COMMENTS 

We received comments on the draft report from AHRQ and CMS. 

AHRQ. AHRQ concurred with our recommendations, stating that 

adverse events affect hospital patients at an “alarming rate” and that it 

must continue working to improve patient safety. 

In response to our recommendation to broaden patient safety efforts to 

include all types of adverse events, AHRQ noted that the types of events 

vary widely and that efforts should be broadened beyond prescribed lists 

of adverse events. AHRQ stated that it has sponsored efforts to address 

specific types of adverse events and to address causes that contribute to 

a wide variety of adverse events. AHRQ also cited the recent 

development of its Common Formats, a set of event definitions and 

reporting forms not limited to a specific list of events designed for 

hospitals to use to report events to PSOs. 

In response to our recommendation to enhance efforts to identify 

adverse events, AHRQ stated that it intends to foster continued 

improvement in both identifying and reducing adverse events through 

operational programs, research efforts, and further collaboration with 

other agencies. Specifically, AHRQ noted that the Common Formats 

facilitate identification of events for both internal hospital purposes and 

reporting to PSOs. AHRQ also cited a continued commitment to its 

Patient Safety Indicators methodology as a way to identify events in 

administrative data and a planned expansion of the MPSMS program, 

which identifies adverse events in medical records acquired through 

CMS. AHRQ plans to expand the MPSMS by broadening the areas of 

clinical investigation, seeking to address all patient populations rather 

than only Medicare beneficiaries, and working toward sharing the 

MPSMS methodology with other organizations. 

CMS. CMS concurred with our recommendations and stated that it is 

committed to the reduction of adverse events in hospitals and other 

health care settings. CMS provided details about current activities and 

future plans to reduce adverse events, concluding that although it has 

taken significant steps to address these issues, more work needs to be 

done. 

In response to our recommendation to broaden patient safety efforts to 

include all types of adverse events, CMS stated that it will “aggressively 

pursue” broadening the scope and definition of patient safety efforts to 

be more inclusive of various types of adverse events. As an example, 

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RECOMMENDATIONS 

CMS noted that it is expanding hospital reporting of quality data to 

include more measures of adverse events. 

In response to our recommendation to enhance efforts to identify 

adverse events, CMS stated that it will continue to use POA indicators 

in implementing its Medicare HAC policy. CMS also referenced the use 

of POA indicators by QIOs to assist hospitals in reducing high-risk 

pressure ulcers and indicated that it is assessing the broader use of 

POA indicators by QIOs to assess the incidence of adverse events and 

assist hospitals in developing quality improvement plans. 

In response to our recommendation to provide further incentives for 

hospitals to reduce the incidence of adverse events through payment 

and oversight, CMS stated its commitment to more closely monitor and 

address hospital quality of care. Specifically, CMS plans to strengthen 

the Medicare HAC policy by considering the appropriateness of 

expanding the conditions included, applying the policy to more health 

care settings, and working to improve the coding and reporting of POA 

indicators. CMS also stated that it is working toward improving 

evaluation of the hospital conditions of participation related to patient 

safety, developing interpretive guidelines and training for surveyors, 

and tasking QIOs with greater responsibility to address adverse events 

in hospitals. Further, CMS points to opportunities presented by the 

ACA, including implementation of the Hospital Value-Based Purchasing 

Program, which will use hospital performance as a basis for incentive 

payments; and creation of the Center for Medicare & Medicaid 

Innovation, which will address improvement in patient safety and 

reduction of adverse events. 

For the full text of AHRQ and CMS comments, see Appendix I. We 

made minor changes to the report based on technical comments. 


 APPENDIX ~ A 

Tax Relief and Health Care Act of 2006

P.L. No. 109-432 § 203

DIVISION B – MEDICARE AND OTHER HEALTH PROVISIONS

TITLE II—MEDICARE BENEFICIARY PROTECTIONS

SEC 203 OIG STUDY OF NEVER EVENTS

(a) Study.— 

(1) In general.—The Inspector General in the Department of Health and 

Human Services shall conduct a study on— 

(A) incidences of never events for Medicare beneficiaries, including 

types of such events and payments by any party for such events; 

(B) the extent to which the Medicare program paid, denied payment, or 

recouped payment for services furnished in connection with such events 

and the extent to which beneficiaries paid for such services; and 

(C) the administrative processes of the Centers for Medicare & Medicaid 

Services to detect such events and to deny or recoup payments for 

services furnished in connection with such an event. 

(2) Conduct of study.—In conducting the study under paragraph (1), the 

Inspector General— 

(A) shall audit a representative sample of claims and medical records of 

Medicare beneficiaries to identify never events and any payment (or 

recouping of payment) for services furnished in connection with such 

events; 

(B) may request access to such claims and records from any Medicare 

contractor; and 

(C) shall not release individually identifiable information or facilityspecific information. 

(b) Report.—Not later than 2 years after the date of the enactment of 

this Act, the Inspector General shall submit a report to Congress on the 

study conducted under this section. Such report shall include 

recommendations for such legislation and administrative action, such as 

a noncoverage policy or denial of payments, as the Inspector General 

determines appropriate, including— 

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APPENDIX ~ A 

(1) recommendations on processes to identify never events and to deny 

or recoup payments for services furnished in connection with such 

events; and 

(2) a recommendation on a potential process (or processes) for public 

disclosure of never events which— 

(A) will ensure protection of patient privacy; and 

(B) will permit the use of the disclosed information for a root cause 

analysis to inform the public and the medical community about safety 

issues involved. 

(c) Funding.— Out of any funds in the Treasury not otherwise 

appropriated, there are appropriated to the Inspector General of the 

Department of Health and Human Services $3,000,000 to carry out this 

section, to be available until January 1, 2010. 

(d) Never Events Defined.—For purposes of this section, the term “never 

event” means an event that is listed and endorsed as a serious 

reportable event by the National Quality Forum as of 

November 16, 2006. 

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National Quality Forum Serious Reportable Events 

Table B-1: The National Quality Forum (NQF) List of Serious Reportable Events 

Surgical Events 

A. Surgery performed on the wrong body part 

B. Surgery performed on the wrong patient 

C. Wrong surgical procedure performed on a patient 

D. Unintended retention of foreign object in a patient after surgery or procedure 

E. Intraoperative or immediately postoperative death 

Product or Device Events 

A. Patient death or serious disability associated with use of contaminated drugs, devices, or biologics provided by the health care facility 

B. Patient death or serious disability associated with use or function of a device in patient care in which the device is used or functions 

other than as intended 

C. Patient death or serious disability associated with intravascular air embolism that occurs while being cared for in a health care facility 

Patient Protection Events 

A. Infant discharged to the wrong person 

B. Patient death or serious disability associated with patient elopement 

C. Patient suicide, or attempted suicide resulting in serious disability, while being cared for in a health care facility 

Care Management Events 

A. Patient death or serious disability associated with a medication error 

B. Patient death or serious disability associated with a hemolytic reaction because of administration of incompatible blood or blood 

products 

C. Maternal death or serious disability associated with labor or delivery in a low-risk pregnancy while cared for in a health care facility 

D. Patient death or serious disability associated with hypoglycemia, the onset of which occurs while patient is being cared for in a health 

care facility 

E. Death or serious disability associated with failure to identify and treat hyperbilirubinemia in neonates 

F. Stage III or Stage IV pressure ulcers acquired after admission to a health care facility 

G. Patient death or serious disability because of spinal manipulative therapy 

H. Artificial insemination with the wrong donor sperm or wrong egg 

Environmental Events 

A. Patient death or serious disability associated with an electric shock while being cared for in a health care facility 

B. Any incident in which a line designated for oxygen or other gas to be delivered to a patient contains the wrong gas or is contaminated by 

toxic substances 

C. Patient death or serious disability associated with a burn incurred from any source while being cared for in a health care facility 

D. Patient death or serious disability associated with a fall while being cared for in a health care facility 

E. Patient death or serious disability associated with the use of restraints or bedrails while being cared for in a health care facility 

Criminal Events 

A. Care provided by someone impersonating a health care provider 

B. Abduction of a patient of any age 

C. Sexual assault on a patient within or on the grounds of a health care facility 

D. Death or significant injury resulting from a physical assault that occurs within or on the grounds of the facility 

Source: NQF, Serious Reportable Events in Health Care 2006 Update: Consensus Report, NQF, Washington, DC, 2007, p. 7.

 APPENDIX ~ B 

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Medicare Hospital-Acquired Conditions 

Table C-1: Medicare Hospital-Acquired Conditions

Conditions

1. Foreign object retained after surgery 

2. Air embolism 

3. Blood incompatibility 

4. Pressure ulcers (stages III and IV) 

5. Falls 

A. Fracture 

B. Dislocation 

C. Intracranial injury 

D. Crushing injury 

E. Burn 

F. Electric shock 

6. Manifestations of poor glycemic control 

A. Hypoglycemic coma 

B. Diabetic ketoacidosis 

C. Nonkeototic hyperosmolar coma 

D. Secondary diabetes with ketoacidosis 

E. Secondary diabetes with hyperosmolarity 

7. Catheter-associated urinary tract infection 

8. Vascular catheter-associated infection 

9. Deep vein thrombosis/pulmonary embolism associated with the following 

A. Total knee replacement 

B. Hip replacement 

10. Surgical site infection 

A. Mediastinitis after coronary artery bypass graft 

B. Associated with certain orthopedic procedures involving the 

a. Spine 

b. Neck 

c. Shoulder 

d. Elbow 

C. Associated with certain bariatric surgical procedures for obesity 

a. Laparoscopic gastric bypass 

b. Gastroenterostomy 

c. Laparoscopic gastric restrictive surgery

Source: Fiscal Year 2009 Final Inpatient Prospective Payment System Rule, 73 Fed. Reg. 48434, 48471 

(Aug. 19, 2008). 

 APPENDIX ~ C 

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 APPENDIX ~ D 

Glossary of Selected Terms67

Acute coronary syndrome—Condition in which the heart does not 

receive enough oxygen-rich blood, often marked by severe chest pain, 

unstable angina, and/or heart attack.

Acute renal insufficiency—Sudden loss of the kidneys’ ability to remove 

waste, also referred to as acute kidney failure.

Adverse event—Harm to a patient as a result of medical care. For 

purposes of this study, we defined adverse events as events that met at 

least one of the following criteria: an event on the National Quality 

Forum list of Serious Reportable Events; an event on Medicare’s list of 

hospital-acquired conditions (HAC) for which it denies higher payment; 

or an event resulting in one of the four most serious categories on a 

patient harm index (classified on the index as F-I): prolonged hospital 

stay, permanent harm, life-sustaining intervention, or death. 

Anticoagulant—Medication that hinders blood coagulation, typically 

used to avoid blood clots and referred to as blood-thinning medication. 

Aspiration—Accidental inhalation of foreign material into the lungs. 

Congestive heart failure—Condition in which the heart is unable to 

maintain adequate circulation of blood in the tissues of the body. 

Deep vein thrombosis (DVT)—Formation of a thrombus (blood clot) 

within a deep vein (as of the leg or pelvis) that is life threatening if 

dislodgment results in blockage to the pulmonary (lung) artery. 

Delirium—Mental disturbance characterized by confusion, disordered 

speech, and hallucinations. 

Dialysis—Medical procedure to remove wastes and toxins from the 

blood, and to adjust fluid and electrolyte imbalances. 

Dysrthymia—Condition of abnormal cardiac (heart) rhythm. 

Hypoglycemia—Condition of abnormally low blood sugar (glucose) level. 

Hypotension—Condition of abnormally low blood pressure. 

 39 

67 Clinical definitions adapted from the National Institutes of Health, U.S. National 

Library of Medicine, Medline Plus Medical Dictionary, updated February 2003. Accessed at 

http://www.nlm.nih.gov on January 7, 2009. 

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APPENDIX ~ D 

Iatrogenic pneumothorax—Condition induced by therapeutic 

intervention in which air or other gas occurs in the pleural cavity. 

Ileus—Partial or complete obstruction of the bowel, marked by a painful 

distended abdomen, vomiting, toxemia, and dehydration. 

Intravenous (IV) infiltrate—Condition in which fluids administered by 

entering a vein accidentally enter the surrounding tissue. 

Intravenous (IV) volume overload—Condition in which fluid is given by 

vein at a higher rate or larger volume than can be absorbed or excreted. 

Obstipation—Condition of severe constipation (abnormally delayed 

passage of dry, hardened feces) that can result in bowel obstruction. 

Pressure ulcer—Ulceration of tissue deprived of adequate blood supply 

by prolonged pressure, also called decubitus ulcer and bedsore. 

Pressure ulcers are classified into four stages: Stage I is intact skin 

with nonblanchable redness; Stage II is a shallow ulcer or blister 

indicating damage to the epidermis; Stage III is damage extending 

through all the layers of the skin; and Stage IV is damage through all 

the layers of the skin and underlying muscle, tendons, or bone.68 

Pulmonary embolism—Obstruction of a pulmonary (lung) artery, often 

marked by shortness of breath; chest pain with inhalation; and, in 

severe cases, low blood pressure and death. 

Sepsis—Systemic response to a serious, usually localized infection of 

bacterial origin, such as systemic inflammatory response syndrome. 

Tachycardia—Condition of rapid heart rate. 

Temporary harm event—Harm to patient that required intervention but 

did not cause lasting harm, classified as E level on patient harm index. 

Thrush—Inflammation of the mouth and throat, caused by fungus. 

Urinary tract infection (UTI)—Infection of the tract through which urine 

passes and can include the kidney, ureters, bladder, and/or urethra. 

Ventilator-associated pneumonia (VAP)—Disease of the lungs 

characterized by inflammation of lung tissue and caused chiefly by 

infection that enters the lungs through a ventilator.

68 National Pressure Ulcer Advisory Panel (NPUAP), Pressure Ulcer Stages Revised by 

NPUAP. Accessed at http://www.npuap.org on November 12, 2009. 


 APPENDIX ~ E 

Methodology for Identifying Events and Determining 

Preventability 

Screening for Potential Adverse Events 

We conducted a two-stage review to identify adverse events. The first 

stage included three screening methods designed to identify 

beneficiaries who appeared likely to have experienced adverse events. 

A beneficiary was considered likely to have experienced an adverse 

event if any screening method found at least one potential adverse event 

during any of the beneficiary’s hospital stays. The screening process 

enabled us to reduce the number of cases requiring second-level review 

of the full medical records by a physician. Additionally, physician 

reviewers indicated that the results of the screening methods helped 

them to more readily identify potential adverse events for consideration. 

The screening methods included: 

 analysis by certified medical coders of Present on Admission (POA) 

Indicators included in Medicare claims data to identify any 

diagnoses that were acquired during the hospital stay; 

 screening of medical records by nurse reviewers using a modified 

version of the Institute for Healthcare Improvement’s Global Trigger 

Tool (IHI GTT) for triggers that could indicate an event, such as 

laboratory test results indicating an infection; and 

 identification of any beneficiaries who were readmitted to the 

hospital within 30 days after their October 2008 hospital discharges. 

Analysis of POA Indicators. Using data from the National Claims 

History file, certified medical coders reviewed the POA indicator data 

included in hospital Medicare claims for each sample beneficiary. A 

recent addition required of Medicare Part A claims, the POA indicator 

codes require hospitals to make a clinical distinction about whether 

diagnoses are present at the time of admission. The coders first verified 

the accuracy of each POA indicator by reviewing the medical records 

and then flagged each diagnosis that had a POA indicator of “N” (not 

present on admission), “W” (clinical staff unable to determine), or “U” 

(documentation insufficient to determine). Analysis of POA indicators 

identified 297 beneficiaries for the second stage of the review. 

Nurse reviews of medical records. Contracted registered nurses 

conducted a preliminary review of medical records for each sample 

beneficiary to identify potential adverse events. Reviewers used a 

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APPENDIX ~ E 

modified version of the IHI GTT protocol, in which reviewers identified 

triggers in the medical records possibly indicative of adverse events and 

then explored the records further to determine whether events occurred 

and the resulting level of harm. Medical records screening identified 

372 cases for inclusion in the second stage of review. 

Readmissions. We identified 92 sample beneficiaries who were 

readmitted to the hospital within 30 days after their discharges in 

October 2008 and included these cases in the second stage of review. 

We reviewed records for admissions that occurred within 30 days of the 

beneficiaries’ last discharges; therefore, the 30-day window for 

reviewing readmissions did not span a fixed timeframe but began on the 

discharge date for each beneficiary. 

Flagged hospital stays. We identified 420 beneficiaries for the second 

stage of review, a review of the hospital medical records by physicians. 

Of the 420 beneficiaries, we identified 391 with the 3 screening methods 

and 29 from additional analysis. In the 29 additional cases, the 

beneficiaries were not flagged on the 3 screening methods, but staff 

involved in the screening process (nurses, coders, or analysts) believed 

complexities in the cases warranted physician review. 

Identifying Events Within Flagged Cases 

Five contracted physicians conducted medical records review of the 

420 cases identified by the screening methods. Physician reviewers 

represented a variety of specializations and experience: an infectious 

disease specialist, a cardiologist, an orthopedic surgeon, an intensivist 

(intensive care specialist), and an internist. All five had many years of 

clinical experience, as well as prior experience in detecting adverse 

events in medical records. Three of the five served as physician 

reviewers for a 2008 Office of Inspector General (OIG) case study.69

Over 12 weeks, the physician reviewers examined hospital medical 

records for each of the 420 cases.70 Physician reviewers used a 

structured medical review protocol that required them to describe each 

adverse event; identify the medical record documentation that led to 

69 OIG, Adverse Events in Hospitals: Case Study of Incidence Among Medicare 

Beneficiaries in Two Counties, OEI-06-08-00220, December 2008. 

70 These included medical records for all hospital stays for sample beneficiaries ending with 

October 2008 discharges. Additionally, physicians reviewed records for any readmissions of 

sample beneficiaries that occurred within 30 days after their final October discharges to look 

for evidence of events that occurred during the October 2008-discharged stays. 

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APPENDIX ~ E 

their identification of the event; and specify the level of harm 

experienced by the patient, with harm categorized in accordance with 

the National Coordination Council for Medication Errors Reporting and 

Prevention Index of Categorizing Medication Errors. 

Throughout our study preparation, medical records review, and 

analysis, we facilitated 22 weekly conference calls during which the 

physician reviewers discussed the review protocol and sample cases that 

either were complex or had possible implications for other cases. These 

calls assisted in making determinations for difficult cases and helped 

achieve consistency across reviewers. The physicians determined that 

the following types of cases would require group discussion: events 

assessed as clearly preventable; events contributing to death; and cases 

involving respiratory failure, hypoglycemia, hypotension, urinary tract 

infections, and complex and/or lengthy surgeries. Physicians also often 

brought cases to group discussion if they involved care specific to a 

specialization of another physician. We documented the discussions and 

conclusions made during these weekly calls, continually revising a 

written physician guidance document to further promote consistency. 

The physicians discussed 162 of the 302 events (54 percent) and other 

cases that the group ultimately determined did not include events. 

Determining Preventability for Each Event 

As part of the structured medical review protocol, reviewers also 

assessed the likelihood that the events were preventable. In 

collaboration with the physicians, we created an initial response scale: 

 Preventable—Patient harm could have been avoided through 

improved assessment or alternative actions. 

 Not preventable—Patient harm could not have been avoided given the 

complexity of the patient’s condition or the care required. 

 Unable to determine—Physicians were unable to determine 

preventability because of incomplete documentation or case 

complexity. 

Through the pretest process, we expanded the scale to enable physicians 

to more precisely gauge the extent to which an event was preventable. 

The expanded scale divided the preventable and nonpreventable 

responses with the descriptors clearly and likely. Assessing an event as 

clearly preventable or clearly not preventable required a greater degree 

of certainty on the part of the reviewer. The expanded scale enabled 

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APPENDIX ~ E 

physicians to make more precise determinations, while our primary 

statistics continued to collapse clearly and likely. 

To make distinctions about the circumstances in each case, physicians 

used their clinical experience and judgment. They considered all 

evidence in the medical records, including staff actions and the patient’s 

condition. Physicians also used information about accepted standards of 

care, the frequency with which certain events occurred despite 

appropriate assessment and care, the physicians’ individual clinical 

experiences, guidance developed during the review process, and group 

discussion of cases. Using a list of contributing factors gleaned from 

prior research, physicians indicated the rationale for each 

determination and provided a narrative description for each case. 

To improve consistency, physician reviewers used a uniform method for 

reviewing preventability. Reviewers developed a decision algorithm 

during practice reviews consisting of a series of questions that led the 

reviewers to a suggested response. Questions addressed issues such as 

whether there was a medical error, whether the event could have been 

anticipated, and how frequently the event occurred given proper care. 

Physicians did not automatically accept the suggested response, but 

assessed whether it was appropriate for each case. In completing the 

rationale section of the protocol, physicians assessed contributing 

factors. The list of contributing factors included broad concepts from 

the decision algorithm, such as errors, and more nuanced factors, such 

as whether the patient was monitored or was susceptible to the event. 

We required that physicians discuss all clearly preventable

determinations during group meetings (as they required greater 

certainty), and encouraged them to bring other cases for discussion if 

they had difficulty or felt the cases would inform other determinations. 

Figure E-1 illustrates the preventability review process. 

Physician Review of Findings 

Following the medical records review, we analyzed the identified events, 

harm levels, and preventability determinations to identify any 

inconsistencies and discussed these with the full physician group. This 

process resulted in some changes to the initial determinations, such as 

collapsing a series of events into a single cascade event.71 

 44 

71 Based on OIG interviews with IHI staff, IHI defines a cascade event as one in which an 

initial event causes a series of related events for the same patient and advocates collapsing 

these into a single event. 

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APPENDIX ~ E 

Figure E-1: Physician Review Process for Determining Preventability 

Q1: Was an identifiable error or 

system failure documented in the 

medical record?

Q2: Could the care provider have 

anticipated this event with the 

information available at the time?

Clearly or likely not preventable

Q3: Were appropriate precautions 

taken to prevent this event? 

Clearly or likely preventable

Q4: How frequently does this type 

of adverse event occur when proper 

preparation and procedures are in 

place?

Yes

No

No

Unable to determine

Clearly or likely preventable Rarely

Part I – Decision Algorithm To Determine Suggested Response 

Clearly or likely not preventable Occasionally

Part II – Rationale List To Evaluate Suggested Response

Do you feel confident that the 

suggested response is appropriate?

Clearly or likely preventable

Yes Make selection in protocol

No

Yes

No

Yes

Request group discussion

Clearly or likely not preventable

Consider the rationale list for the suggested response: 

Preventable

medical error

substandard treatment

inadequate monitoring

inadequate assessment

necessary treatment not provided

event rarely happens

poor communication

flawed safety systems

breakdown in environment

Not Preventable

proper procedures followed

patient highly susceptible

could not have anticipated

patient's condition complex

Unable To Determine

poor or absent documentation

medical care complex

patient's condition complex

Source: OIG illustration of physician medical record review process for determining preventability. 

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 APPENDIX ~ F 

Estimates, Confidence Intervals, and Key Statistics 

We computed incidence rates and corresponding 95-percent confidence 

intervals using the computer program Sudaan. Sudaan is a statistical 

analysis program with appropriate standard statistical formulas for 

calculating correct standard errors for complex sampling designs. 

Table F-1: Estimates, Confidence Intervals, and Key Statistics 

 46 

95-Percent 

Confidence 

Interval 

95-Percent 

Confidence 

Interval 

n 

Estimated 

Percentage of 

Beneficiaries 

Lower 

Bound

Upper 

Bound

Estimated 

Number of 

Beneficiaries 

Lower 

Bound

Upper 

Bound

Event Experiences for All Beneficiaries (n=780) 

Experienced adverse events 105 13.46% 11.24% 16.05% 133,710 111,644 159,421 

 National Quality Forum Serious 

Reportable Events* 5 0.64% 0.27% 1.53% 6,367 2,682 15,197

 Medicare hospital-acquired 

conditions* 8 1.03% 0.51% 2.04% 10,187 5,066 20,263

 F-I level adverse events 102 13.08% 10.88% 15.63% 129,890 108,069 155,249 

 Events that overlap at least two 

categories* 9 1.15% 0.60% 2.20% 11,461 5,960 21,852 

 Events that overlap all three 

categories* 1 0.13% 0.02% 0.91% 1,273 199 9,039 

Experienced temporary harm 

events 105 13.46% 11.24% 16.05% 133,710 111,644 159,421 

Experienced only preventable 

adverse events 58 7.44% 5.79% 9.50% 73,859 57,511 94,361 

Experienced only preventable 

temporary harm events 49 6.28% 4.78% 8.22% 62,398 47,479 81,647 

Experienced adverse events that 

contributed to death* 12 1.54% 0.87% 2.69% 15,281 8,642 26,719 

Beneficiaries Who Experienced at Least One Adverse Event (n=105) 

Experienced multiple adverse 

events 19 18.10% 11.84% 26.66% 24,195 15,831 35,647 

Experienced temporary harm in 

addition to adverse events 29 27.62% 19.91% 36.94% 36,929 26,622 49,392 

Experienced cascade events 28 26.67% 19.08% 35.93% 35,656 25,512 48,042 

Beneficiaries Who Experienced at Least One Temporary Harm Event (excluding those who experienced adverse 

events) (n=105) 

Experienced multiple temporary 

harm events 23 21.90% 15.00% 30.83% 29,289 20,057 41,223 

Beneficiaries Who Experienced Events and Were Covered Under the Inpatient Prospective Payment System (IPPS) 

(n=171)

Incurred additional costs 28 16.37% 11.54% 22.71% 35,656 25,129 49,453 

Did not incur additional costs 143 83.63% 77.29% 88.46% 182,101 168,304 192,628 

*Given the small proportions, confidence intervals for projected numbers exceed 50-percent relative precision.

Source: Office of Inspector General (OIG) analysis of hospital stays and Medicare claims for 780 Medicare beneficiaries discharged in 

October 2008. 

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APPENDIX ~ F 

Table F-2: Estimates, Confidence Intervals, and Key Statistics 

 47 

95-Percent Confidence Interval 

n Percentage Estimate Lower Bound Upper Bound 

Preventability Classification for All Adverse Events and Temporary Harm Events (n=302) 

All adverse and temporary harm events 302 100% NA NA

 Preventable events 133 44.04% 38.06% 50.19%

o Clearly preventable events 28 9.27% 6.53% 13.01%

o Likely preventable events 105 34.77% 29.20% 40.79%

 Not preventable events 155 51.32% 45.22% 57.39%

o Clearly not preventable events 55 18.21% 13.92% 23.47%

o Likely not preventable events 100 33.11% 27.59% 39.14%

 Unable to determine* 14 4.64% 2.80% 7.59%

Clinical Category for All Adverse Events (n=128) 

All clinical categories 128 100% NA NA 

 Medication 40 31.25% 23.35% 40.41%

 Patient care 36 28.13% 20.92% 36.66% 

 Surgery and other procedures 33 25.78% 18.77% 34.31% 

 Infection 19 14.84% 9.64% 22.18% 

Clinical Category for All Temporary Harm Events (n=174) 

All clinical categories 174 100% NA NA 

 Medication 73 41.95% 34.74% 49.53%

 Patient care 63 36.21% 29.09% 43.98%

 Surgery and other procedures 32 18.39% 12.92% 25.50%

 Infection 6 3.45% 1.58% 7.36%

Harm Level for All National Coordinating Council Medication Errors Reporting and Prevention Index for Categorizing 

Errors F-I Level Events (n=122)**

All NCC MERP harm levels 122 100% NA NA 

 Harm F 76 62.30% 53.42% 70.41%

 Harm G* 6 4.92% 2.22% 10.54%

 Harm H 28 22.95% 16.15% 31.54%

 Harm I* 12 9.84% 5.75% 16.33%

Preventable Adverse and Temporary Harm Events Within Each Clinical Category 

 Infection (n=25) 15 60.00% 39.72% 77.35%

 Medication (n=113) 57 50.44% 40.98% 59.87% 

 Patient care (n=99) 50 50.51% 40.47% 60.50%

 Surgery and other procedures (n=65) 11 16.92% 9.51% 28.30%

continued on next page 

*Given the small proportions, confidence intervals for projected numbers exceed 50-percent relative precision. 

** National Coordinating Council for Medication Errors Reporting and Prevention Index for Categorizing Errors (NCC MERP). 

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APPENDIX ~ F

Table F-2: Estimates, Confidence Intervals, and Key Statistics (Continued)

 48 

95-Percent Confidence Interval 

n Percentage Estimate Lower Bound Upper Bound 

Physician Rationale for All Preventable Events (n=133) 

Error related to medical judgment, skill, or 

patient management 77 57.89% 49.04% 66.27%

Appropriate treatment was provided in a 

substandard way 61 45.86% 37.64% 54.33%

Patient’s progress was not adequately 

monitored 50 37.59% 29.76% 46.14%

Patient’s health status was not adequately 

assessed 30 22.56% 15.87% 31.02%

Necessary treatments were not provided 22 16.54% 11.10% 23.92%

Event rarely happens when proper 

precautions and procedures are followed 18 13.53% 8.46% 20.95%

Poor communication between caregivers* 10 7.52% 3.86% 14.14%

Facility’s patient safety systems and policies 

were inadequate or flawed* 4 3.01% 1.12% 7.81%

Breakdown in hospital environment 

occurred (equipment failure, etc.)* 2 1.50% 0.38% 5.80%

Physician Rationale for All Nonpreventable Events (n=155)

Event occurred despite proper assessment 

and procedures followed 96 61.94% 52.82% 70.28%

Patient was highly susceptible to event 

because of health status 77 49.68% 41.34% 58.04%

Care provider could not have anticipated 

event given information available 54 34.84% 27.54% 42.92%

Patient’s diagnosis was unusual or complex, 

making care difficult 45 29.03% 21.67% 37.70%

Harm was anticipated but was considered 

acceptable given alternatives* 21 13.55% 8.75% 20.40%

*Given the small proportions, confidence intervals for projected numbers exceed 50-percent relative sion. preci

Source: OIG analysis of hospital stays for 780 Medicare beneficiaries discharged in October 2008.

Table F-3: Statistical Test Results for Preventability Subanalysis 

P-Value for 

Difference 

Statistical Test in Proportions 

Test for relationship among preventability determinations and harm events (i.e., adverse event or 

temporary harm event) 0.0568 

Test for relationship between preventability determinations and clinical categories (e.g., surgical event, 

medication event, patient care event, or infection) <0.0001* 

Test for difference between preventability determinations 

 Surgical events versus infection events 

 Surgical events versus medication events 

 Surgical events versus patient care events 

0.0013* 

<0.0001* 

<0.0001* 

Test for difference of means between average additional costs incurred by entire stays and average 

additional costs attributed to events within the initial hospital stays 0.0104* 

Note: Weighted chi square and Cochran-Mantel-Haenszel chi square produced similar results. 

* P-values are statistically significant at the 95 precent confidence level. 

Source: OIG analysis of hospital stays and Medicare claims for 780 Medicare beneficiaries discharged in October 2008. 

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APPENDIX ~ F 

Table F-4: Projections and Confidence Intervals for Analysis of Medicare Costs 

Associated With Adverse Events and Temporary Harm Events 

95-Percent Confidence Interval 

Projected 

Population 

Projected 

Cost Estimate Lower Bound Upper Bound

Medicare Inpatient Costs for Projected Population (n=657)

Estimate of Medicare inpatient costs 836,646 $9,167,576,966 $8,505,456,013 $9,829,697,918 

Medicare Inpatient Costs for Projected Population Associated With Adverse and Temporary Harm Events (n=657) 

Costs associated with all events 836,646 $324,155,814 $161,745,099 $486,566,529 

Costs associated with preventable events 836,646 $118,720,272 $33,915,875 $203,524,670 

Source: OIG analysis of hospital stays and Medicare claims for 780 Medicar beneficiaries discharged in October 2008. e

* Medicare costs are calculated based on the 657 sample cases in the IPPS.

Table F-5: Projections and Confidence Intervals for Average Additional Medicare Costs

Associated With Adverse Events and Temporary Harm Events

95-Percent Confidence Interval Projected 

Average 

Events Resulting in Increased Medicare Costs Additional Cost Lower Bound Upper Bound

Events resulting in increased costs for additional hospital 

stays (n=12) $13,745 $7,760 $19,730 

Events resulting in increased costs for initial hospital 

stays (n=16) $5,601 $3,889 $7,313 

Source: OIG analysis of hospital stays and Medicare claims for 780 Medicare beneficiaries discharged in October 2008.

Table F-6: Percentage Estimates and Confidence Intervals for Medicare Costs 

Associated With Adverse Events and Temporary Harm Events

95-Percent Confidence Interval 

Percentage 

Estimate Lower Bound Upper Bound

Percentage of Total Medicare IPPS Costs 

All adverse and temporary harm events 3.54% 1.82% 5.26%

Preventable adverse and temporary harm events 1.30%* 0.38% 2.21%

Percentage of Medicare IPPS Costs Attributed to Adverse Events and Temporary Harm Events

Associated with adverse events 87.48% 73.70% 100.00%

Associated with temporary harm events 14.93%* 0.34% 29.52%

Associated with entire additional hospital stays 64.80% 43.82% 85.77%

*Given the small proportions, confidence intervals for projected numbers exceed 50-percent relative precision. Source: OIG analysis of hospital stays and Medicare claims for 780 Medicare beneficiaries discharged in October 2008.


 APPENDIX ~ G 

Rates of Adverse Events and Temporary Harm Events by Patient 

Days and Hospital Admissions 

Hospitals commonly measure adverse events by incidence density, 

which takes into account the period during which patients are observed. 

For example, incidence density is often used in measuring hospitalacquired infections because risk can increase with the length of 

exposure to the health care environment.72 The Institute for Healthcare 

Improvement (IHI), a nonprofit advisory group to hospitals, cites 

advantages to using incidence density metrics over standard incidence 

rates that measure the number of events per patient.73 IHI reports that 

measuring total events by patient days or hospital admissions enables 

hospitals to count multiple events experienced by the same beneficiary. 

The sample of 780 Medicare beneficiaries discharged during 

October 2008 included 838 total hospital stays (admissions) and a total 

of 4,354 days in the hospital (patient days). We calculated patient days 

by subtracting the admission date for each hospital stay from its 

discharge date.74 Table G-1 provides ratios for adverse events and 

temporary harm events in the sample per 1,000 patient days and 

per 100 admissions.

Table G-1: Rates of Adverse and Temporary Harm Events in 

the Sample by Patient Days and Hospital Admissions

Per 1,000 

Patient-Days Category Per 100 Admissions 

Adverse events 29 15 

Temporary harm events 40 21 

Adverse events and temporary harm events combined 69 36 

Source: Office of Inspector General analysis of hospital stays for 780 Medicare beneficiaries in 

October 2008.

72 K.M. Arias, Outbreak Investigation, Prevention, and Control in Health Care Settings, 

Second Edition, 2009, Jones and Bartlett Publishers, pp. 330–331. 

73 IHI, IHI Global Trigger Tool for Measuring Adverse Events, Second Edition, 2009, p. 13. 

74 In consultation with physician reviewers, we excluded the seven patients admitted and 

discharged on the same day (these patients did not experience temporary harm or adverse 

events). IHI recommends selecting patient records for only hospital stays of at least 24 hours. 

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

APPENDIX ~ A APPENDIX ~ H 

Adverse Events and Temporary Harm Events

Tables H-1 and H-2 contain information about adverse events and 

temporary harm events identified in the sample, including National 

Quality Forum (NQF) Serious Reportable Events and Medicare 

hospital-acquired conditions (HAC). Table H-1 contains information 

about adverse events (128 adverse events).75 Table H-2 contains 

information about temporary harm events (174 events). The event 

descriptions vary somewhat depending upon the language the physician 

reviewers used to describe the event and the level of detail included in 

their notes. 

Table H-1: Adverse Events by Clinical Category, Harm Level, Preventability, and 

Whether the Events Were NQF Serious Reportable Events or Medicare HACs (n=128)

 51 

Harm 

Level Adverse Event Preventability NQF HAC 

Events Related to Medication (40) 

Excessive bleeding (12) 

1. Abdominal bleeding secondary to anticoagulant given for deep 

vein thrombosis (enoxaparin) I CNP 

2. Brain hemorrhage secondary to anticoagulants (aspirin and 

clopidogrel) F CNP 

3. Cascade event in which delay in care and administration of aspirin 

to patient with low platelet count led to pulmonary hemorrhage I CP 

4. Cascade event in which gastrointestinal bleeding and hematoma 

associated with aspirin and anticoagulant (clopidogrel) given 

following coronary stent placement resulted in acute blood loss 

I CNP 

5. Hematuria secondary to anticoagulant (warfarin) F LP 

6. Retroperitoneal hemorrhage secondary to anticoagulant (warfarin) I CP 

7. Gastrointestinal bleeding secondary to anticoagulant (enoxaparin) I CNP 

8. Gastrointestinal bleeding secondary to anticoagulant (warfarin) F LP 

9. Gastrointestinal bleeding secondary to anticoagulants (aspirin, 

clopidogrel, and enoxaparin) F CNP 

10. Gastrointestinal bleeding secondary to anticoagulants (aspirin, 

clopidogrel, and eptifibatide) F CNP 

11. Gross hematuria secondary to anticoagulants (aspirin and 

clopidogrel) F LNP 

12. Hematoma secondary to anticoagulant (heparin) F LP 

continued on next page 

75 The harm level is classified according to the National Coordinating Council for 

Medication Errors Reporting and Prevention (NCC MERP) Index for Categorizing Errors 

(E–I). Preventability determination is reflective of the physician review index: CP = clearly 

preventable, LP = likely preventable, LNP = likely not preventable, CNP = clearly not 

preventable, and UTD = unable to determine. 

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

APPENDIX ~ H 

Table H-1: Adverse Events by Clinical Category, Harm Level, Preventability, and 

Whether the Events Were NQF Serious Reportable Events or Medicare HACs 

(n=128) (Continued) 

Harm 

Level Adverse Event Preventability NQF HAC 

Events Related to Medication (continued) 

Delirium or change in mental status (7)

1. Cascade event in which narcotic analgesic (hydromorphone) 

induced delirium, which led to use of physical restraints, patient 

pulling out IVs, and patient fall 

F CP 

2. Cascade event in which narcotic analgesic (oxycodone) induced 

delirium and resulted in patient fall F CP 

3. Confusion secondary to narcotic analgesics (dextropropoxyphene 

with acetaminophen) F CP 

4. Delirium secondary to sedative (benzodiazepine) F CNP 

5. Hallucinations and delirium secondary to antiwithdrawal medication 

(naloxone) F CNP 

6. Hallucinations and delirium secondary to narcotic analgesic 

(hydromorphone) F LP 

7. Mental status change due to narcotic analgesic (morphine) F CP 

Hypoglycemic event (6)

1. Episode of severe hypoglycemia secondary to insulin management H LNP 

2. Hypoglycemic coma secondary to insulin management H LP 

3. Hypoglycemic coma secondary to insulin management I LP 

4. Hypoglycemic coma and permanent brain injury secondary to 

insulin management in patient with anoxic encephalopathy 

following cardiac arrest 

G CP 

5. Multiple episodes of severe hypoglycemia secondary to insulin 

management H CP 

6. Recurrent hypoglycemia secondary to diabetes medication 

(glipizide) F CP 

Acute renal insufficiency (kidney failure) (4)

1. Acute renal failure secondary to antihypertensives and diuretics 

(unspecified) F LNP 

2. Acute renal failure secondary to blood pressure medication 

(enalapril) F LP 

3. Acute renal failure and permanent decrease of renal function 

secondary to dehydration from diuretic (furosemide) G LP 

4. Severe acute renal insufficiency and dehydration secondary to 

diuretics (bumetanide and spironolactone) F LNP 

Severe hypotension (4)

1. Hypotension secondary to narcotic analgesic (hydromorphone) F LP 

2. Hypotension secondary to diuretics (unspecified) F LP 

3. Hypotension secondary to multiple psychiatric medications 

(mirtazapine, risperidone, and sertraline) F LP 

4. Hypotension secondary to multiple sedatives (ketamine, 

lorazepam, and propofol) H CNP 

Respiratory complication (4)

1. Acute hypercarbic respiratory failure (excess oxygen) H LP 

2. Cascade event in which narcotic analgesic (hydromorphone) led to 

respiratory failure and recurrent somnolence H LP 

3. Respiratory depression secondary to antianxiety medication 

(lorazepam) and narcotic analgesic (morphine) H LP 

4. Respiratory failure secondary to sedative (benzodiazepine) I CP 

Severe allergic reaction (3)

1. Failure to diagnose Stevens-Johnson Syndrome secondary to 

anticonvulsants (carbamazepine and phenytoin) F LP 

2. Hives and shortness of breath due to allergic reaction to antibiotic F CNP 

3. Throat swelling due to allergic reaction to blood transfusion H CNP 

 continued on next page 

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

 53 

A PPENDIX ~ H 

Table H-1: Adverse Events by Clinical Category, Harm Level, Preventability, and 

Whether the Events Were NQF Serious Reportable Events or Medicare HACs 

(n=128) (Continued) 

Harm 

Level Adverse Event Preventability NQF HAC 

Events Related to Patient Care (36) 

Intravenous (IV) volume overload (10)

1. Cascade event in which cessation of diuretic (furosemide) and 

administration of excess saline led to acute pulmonary edema H LP 

2. Cascade event in which IV volume overload led to mild congestive 

heart failure and subsequent treatment with diuretic (furosemide) led 

to hypokalemia 

F LNP 

3. Hypoxic respiratory failure secondary to IV volume overload H LNP 

4. Hypoxic respiratory failure secondary to IV volume overload H LP 

5. IV volume overload with associated leg edema and complicated by 

preexisting pneumonia F LNP 

6. Pleural effusions and intermittent dyspnea secondary to IV volume 

overload F LNP 

7. Pulmonary edema and effusions secondary to IV volume overload F CNP 

8. Pulmonary edema and respiratory distress secondary to IV volume 

overload H LP 

9. Respiratory failure secondary to IV volume overload H LP 

10. Respiratory insufficiency and reintubation secondary to IV volume 

overload F LNP 

Aspiration (8) 

1. Aspiration associated with feeding tube placement F LP 

2. Aspiration pneumonia associated with food intake I UTD 

3. Aspiration pneumonia associated with unspecified infiltrate F LP 

4. Aspiration pneumonia associated with unspecified infiltrate F LNP 

5. Aspiration pneumonitis associated with unspecified infiltrate F LP 

6. Cascade event in which aspiration led to respiratory failure, acute 

renal failure, shock, and cardiac arrest I UTD 

7. Cascade event in which recurrent aspiration led to infection F LP 

8. Cascade event in which episode of vomiting led to aspiration 

pneumonia in patient with congestive heart failure F LNP 

Venous thrombosis or pulmonary embolism (5)

1. Bilateral deep venous thrombosis F LP 

2. Bilateral pulmonary emboli F LP 

3. Deep venous thrombosis secondary to central catheter F UTD 

4. Multiple pulmonary emboli (right pulmonary artery) F LP 

5. Venous thrombosis (saphenous vein) F LNP 

Exacerbation of preexisting medical condition (5) 

1. Cascade event in which failure to diagnose hypotension and septic 

shock led to severe hypotension H CP 

2. Cascade event in which failure to diagnose postoperative bowel 

distension led to toxic megacolon, bowel perforation, abdominal 

sepsis, and shock 

H UTD 

3. Progressive respiratory difficulties resulting from failure to complete 

congestive heart failure therapy F LP 

4. Progressive respiratory difficulties resulting from failure to diagnose 

hemothorax F LP 

5. Progressive respiratory difficulties resulting from failure to diagnose 

pulmonary infiltrate and pneumonia F CP 

Stage III pressure ulcer (3)

1. Progression from single stage II pressure ulcer to bilateral stage III 

pressure ulcers (buttocks) E LP  

2. Progression from stage I pressure ulcer to stage III pressure ulcer 

(heel) E LP 

3. Stage III pressure ulcer (sacrum) E LP 

continued on next page 

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

APPENDIX ~ H 

Table H-1: Adverse Events by Clinical Category, Harm Level, Preventability, and 

Whether the Events Were NQF Serious Reportable Events or Medicare HACs 

(n=128) (Continued) 

Harm 

Level Adverse Event Preventability NQF HAC 

Events Related to Patient Care (continued) 

Other events related to patient care (5)

1. Breakdown of surgical wound F UTD 

2. Congestive heart failure resulting from failure to manage high blood 

pressure 

F LNP 

3. Hypoxia resulting from failure to stabilize tracheostomy and provide 

oxygen during transfer H CP 

4. Severe back pain and possible vertebral compression fracture from 

patient fall F CNP 

5. Significant episode of weakness and dizziness associated with an 

exacerbation of hyponatremia F LP 

Events Related to Surgery or Other Procedures (33) 

Excessive bleeding (5) 

1. Bleeding for several days following colonoscopy F LNP 

2. Bleeding from femoral artery following IV placement F LNP 

3. Cascade event in which hemorrhage of femoral artery at puncture 

site led to shock, apnea, and ultimately a myocardial infarction H LP 

4. Cascade event in which premature removal of dialysis needle 

resulted in excessive bleeding, shock, intubation, and aspiration H CP 

5. Hematoma following knee arthroplasty F LP 

Severe hypotension (4)

1. Hypotension during hemodialysis treatment F LNP 

2. Hypotension following cardiac surgery F LNP 

3. Hypotension following endoscopic procedure H CNP 

4. Hypotension with atrial fibrillation and rapid ventricular response 

following dialysis treatment F LP 

Respiratory complication (4)

1. Agonal breathing following premature extubation H CP 

2. Cascade event in which acute respiratory failure following 

cardiac procedure led to hematuria and hemoptysis F LNP 

3. Cascade event in which angioedema secondary to contrast 

used for fistulogram led to intubation, ventilator-associated 

pneumonia, and shock 

I CNP 

4. Respiratory distress following percutaneous tracheostomy H CNP 

Iatrogenic pneumothorax (3) 

1. Cascade event in which postoperative pneumothorax led to acute 

respiratory failure H LNP 

2. Cascade event in which removal of chest tube led to pneumothorax, 

reinsertion of chest tube, and reintubation H LNP 

3. Pneumothorax following chest tube placement F CNP 

Postoperative ileus (3) 

1. Cascade event in which outpatient surgery to repair hernia following 

cholecystectomy led to hospitalization for postoperative hypoxemia, 

atelectasis, and ileus 

F LNP 

2. Significant ileus following partial colon resection F CNP 

3. Significant ileus following partial colon resection F LNP 

continued on next page 

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

APPENDIX ~ H 

Table H-1: Adverse Events by Clinical Category, Harm Level, Preventability, and 

Whether the Events Were NQF Serious Reportable Events or Medicare HACs 

(n=128) (Continued) 

Harm 

Level Adverse Event Preventability NQF HAC 

Events Related to Surgery or Other Procedures (continued) 

Postoperative urinary retention (3) 

1. Postoperative urinary retention associated with indwelling urinary 

catheter F LNP 

2. Postoperative urinary retention associated with indwelling urinary 

catheter F LP 

3. Postoperative urinary retention associated with urinary catheter F LNP 

Acute coronary syndrome (2) 

1. Acute coronary syndrome following laparoscopic cholecystectomy 

and resulting in permanent damage to heart muscle G CNP 

2. Acute coronary syndrome that developed as a complication of 

percutaneous coronary intervention F CNP 

Blood clots and other occlusions (blockage within a blood vessel) (2) 

1. Acute occlusion of the popliteal artery following colonoscopy and 

partial colon resection G CNP 

2. Pericardial blood clot following cardiac surgery F LNP 

Cardiac complication (2) 

1. Atrial fibrillation following mitral valve replacement surgery H CNP 

2. Severe ventricular tachycardia following coronary artery bypass 

graft H CNP 

Other procedure-related complication (5) 

1. Cascade event in which coronary bypass surgery led to complex 

tachycardia complicated by hypotension H LNP 

2. Cascade event in which complications following bowel surgery 

resulted in surgical site hemorrhage F LNP 

3. Delay in surgery because of equipment malfunction F LP 

4. Hematuria due to indwelling urinary catheter-associated trauma F LNP 

5. Seroma (pocket of fluid) following stomach resection F LNP 

Events Related to Infection (19)

Urinary tract infection (5)

1. Cascade event in which cystoscopy eroded artificial urethral 

sphincter necessitating use of urinary catheter which led to urinary 

tract infection (E. coli) 

G LP 

2. Urinary tract infection (E. coli) associated with urinary catheter F LP 

3. Urinary tract infection (E. coli) associated with urinary catheter E LP 

4. Urinary tract infection (Klebsiella) associated with urinary catheter E LP 

5. Urinary tract infection (Serratia) associated with urinary catheter E LP 

Vascular catheter-associated infection (central or peripheral line) (4)

1. Cascade event in which vascular catheter led to sepsis, deep vein 

thrombosis, and pulmonary embolism F LP 

2. Cascade event in which vascular catheter led to septicemia and 

deep vein thrombosis F LP 

3. Forearm cellulitis (inflammation of skin or connective tissue) 

following vascular catheter insertion F CP 

4. Methicillin-resistant Staphylococcus aureus (MRSA) infection 

following pleural catheter insertion H LP 

continued on next page 

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

APPENDIX ~ H 

Table H-1: Adverse Events by Clinical Category, Harm Level, Preventability, and 

Whether the Events Were NQF Serious Reportable Events or Medicare HACs 

(n=128) (Continued) 

Harm 

Level Adverse Event Preventability NQF HAC 

Events Related to Infection (continued)

Other bloodstream infections (excluding vascular catheter-associated 

Infections) (4) 

1. Cascade event in which failure to treat systemic inflammatory 

response syndrome led to acute renal failure and aspiration 

pneumonia 

I CP 

2. Cascade event in which removal of urinary catheter led to 

recurrence of obstructive uropathy, renal failure, sepsis, and 

permanent deterioration of renal function 

G CP 

3. Cascade event in which untreated febrile neutropenia led to septic 

shock I CP 

4. Sepsis (methicillin-resistant Staphylococcus epidermis) F LNP 

Respiratory infection (4)

1. Pneumonia (MRSA) following abdominal surgery F LNP 

2. Pneumonia (unspecified) following knee surgery F LNP 

3. Ventilator-associated pneumonia (Klebsiella) F LNP 

4. Ventilator-associated pneumonia (MRSA) H LNP 

Surgical or procedural site infection (2)

1. Cascade event in which anastomotic leak following colectomy led to 

abscesses and bacteremia F LP 

2. Surgical site infection following foot surgery F LNP 

Source: Office of Inspector General (OIG) analysis of hospital stays for 780 Medicare beneficiaries in October 2008.

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

APPENDIX ~ H 

Table H-2: Temporary Harm Events, E Level on the NCC MERP Index, Identified 

Among Medicare Beneficiaries by Clinical Category (n=174 ) 

Temporary Harm Event Preventability 

Events Related to Medication (73) 

Delirium or change in mental status (22)

1. Altered mental status secondary to narcotic analgesic (fentanyl) and sedative 

(midazolam) LP 

2. Cascade event in which delirium secondary to antipsychotic (haloperidol) led to patient 

pulling catheter out which resulted in hematuria LP

3. Confusion and delirium secondary to narcotic analgesics (hydromorphone and 

morphine) LP

4. Confusion secondary to narcotic analgesic (hydromorphone) LP

5. Confusion secondary to sedative (benzodiazepine) LP

6. Delirium secondary to anticonvulsants (valproic acid) CNP 

7. Delirium secondary to local anesthetic (lidocaine) CNP 

8. Delirium secondary to narcotic analgesic (hydromorphone) LP

9. Delirium secondary to narcotic analgesic (hydrocodone with acetaminophen) LP

10. Delirium secondary to narcotic analgesic (morphine) CNP 

11. Drowsiness secondary to narcotic analgesic (hydromorphone) LNP

12. Hallucinations and delirium secondary to narcotic analgesic (morphine) LNP

13. Hallucinations secondary to sedative (alprazolam) and multiple narcotic analgesics UTD

14. Lethargy secondary to narcotic analgesic (hydromorphone) LP 

15. Lethargy secondary to narcotic analgesic (oxycodone with acetaminophen) LP 

16. Omission of antidepressant (fluoxetine with olanzapine) that led to episode of acute 

paranoia LP 

17. Oversedation secondary to antihistamine and sedative (promethazine) LP 

18. Oversedation secondary to multiple psychiatric medications (alprazolam, haloperidol, 

and quetiapine) LNP

19. Oversedation secondary to narcotic analgesic (fentanyl) and sedative (midazolam) LNP

20. Oversedation secondary to narcotic analgesic (hydromorphone) LP 

21. Paranoid delusions secondary to narcotic analgesics (hydromorphone and morphine) LP 

22. Somnolence secondary to narcotic analgesics (hydromorphone and morphine) CP 

Hypoglycemic event (11)

1. Hypoglycemia secondary to diabetes medication (glipizide) UTD 

2. Hypoglycemia secondary to glycemic management CP

3. Hypoglycemia secondary to glycemic management LNP 

4. Hypoglycemia secondary to glycemic management LNP 

5. Hypoglycemia secondary to glycemic management LNP 

6. Hypoglycemia secondary to glycemic management LP

7. Hypoglycemia secondary to glycemic management LP

8. Hypoglycemia secondary to glycemic management LP

9. Hypoglycemia secondary to glycemic management LP

10. Hypoglycemia secondary to glycemic management LP

11. Volatile blood glucose secondary to insulin management LNP

Thrush and other opportunistic infection (7)

1. Fungal infection (cutaneous rash) secondary to antibiotics (unspecified) CNP 

2. Thrush (Candidiasis) secondary to broad spectrum antibiotics (unspecified) CNP 

3. Thrush (oropharyngeal Candida) secondary to antibiotics (piperacillin and tazobactam) CNP 

4. Thrush (unspecified) secondary to antibiotics (unspecified) LNP 

5. Thrush (unspecified) secondary to antibiotics and steroids (unspecified) CNP 

6. Thrush (unspecified) secondary to antibiotics and steroids (unspecified) CNP 

7. Thrush (unspecified) secondary to steroids (unspecified) CNP 

continued on next page 

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

APPENDIX ~ H 

Table H-2: Temporary Harm Events, E Level on the NCC MERP Index, Identified 

Among Medicare Beneficiaries by Clinical Category (n=174) (Continued) 

Temporary Harm Event Preventability 

Events Related to Medication (continued) 

Allergic reaction or side effect related to skin (6)

1. Generalized pruritic (itching) rash secondary to narcotic analgesic (morphine) CNP 

2. Hives and facial swelling due to contrast used during cardiac catheterization LNP 

3. Hives and significant itching secondary to narcotic analgesic (hydromorphone) CNP 

4. Hives secondary to allergic reaction to antibiotics (moxifloxacin) CNP 

5. Itching and erythema (redness) secondary to narcotic analgesic (hydromorphone) CNP 

6. Itching secondary to antibiotics (clindamycin and cephalosporin) CNP 

Gastrointestinal complication (5)

1. Allergic reaction (nausea and vomiting) to narcotic analgesics (hydromorphone) CP 

2. Diarrhea secondary to antibiotic (amoxicillin and clavulanate) UTD 

3. Nausea and vomiting secondary to hypertension therapy (nitroprusside) LNP 

4. Nausea and vomiting secondary to narcotic analgesic (morphine) LNP 

5. Severe diarrhea secondary to laxatives LP

Hypotension (5)

1. Cascade event in which diuretic (furosemide) led to sinus tachycardia, renal 

insufficiency, and hypotension LP 

2. Hypotension and dizziness secondary to antihypertensive medication (unspecified) LP

3. Hypotension following administration of blood pressure medication (metoprolol) CP

4. Hypotension secondary to multiple antihypertensives (unspecified) LP

5. Low blood pressure secondary to aggressive diuresis (enalapril and furosemide) LNP 

Dysrhythmia (3)

1. Dysrhythmia secondary to beta-blocker (labetalol) LNP 

2. Dysrhythmia secondary to cardiac medication (digoxin) LP

3. Palpitations and nausea secondary to bronchodilators (albuterol) CNP 

Excessive bleeding (3)

1. Epistaxis (nasal bleed) secondary to anticoagulant (enoxaparin) CNP 

2. Gross hematuria secondary to anticoagulant (heparin) CNP 

3. Hematuria secondary to anticoagulant (enoxaparin) LNP 

Severe headache or dizziness (3)

1. Extended period of dizziness secondary to opioid withdrawal medication 

(buprenorphine) LP 

2. Headache secondary to cardiac medication (nitroglycerine) LP

3. Nausea and headache secondary to cardiac medication (nitroglycerine) CNP 

Acute renal failure or insufficiency (2)

1. Acute renal failure secondary to radiopaque contrast LNP 

2. Acute renal insufficiency secondary to multiple nephrotoxic agents, including kanamycin 

and ketorolac CP

Allergic reaction to blood or related products (2)

1. Allergic reaction to blood transfusion CNP 

2. Hives during infusion of fresh frozen plasma CNP 

Respiratory complication (2)

1. Hypoxia secondary to narcotic analgesic (meperidine) LP 

2. Respiratory acidosis secondary to narcotic analgesic (hydrocodone with 

acetaminophen) and sedative (alprazolam) CP

Other events related to medication (2)

1. Fever secondary to antiulcer medication used to treat uterine atony (misoprostol) CNP 

2. Urinary retention secondary to narcotic analgesic (opioid) LNP 

continued on next page 

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

APPENDIX ~ H 

Table H-2: Temporary Harm Events, E Level on the NCC MERP Index, Identified 

Among Medicare Beneficiaries by Clinical Category (n=174 ) (Continued) (

Temporary Harm Event Preventability 

Events Related to Patient Care (63)

Stage I, Stage II, or unstaged pressure ulcer (20)

1. Bilateral stage I pressure ulcer (buttocks) LP 

2. Deep tissue injury (buttock) LNP 

3. Progression from stage I pressure ulcer to stage II pressure ulcer (coccyx) CNP 

4. Progression from stage I pressure ulcer to stage II pressure ulcer (coccyx) LNP 

5. Progression from stage I pressure ulcer to stage II pressure ulcer (coccyx) LNP 

6. Stage I pressure ulcer (coccyx) LNP 

7. Stage I pressure ulcer (coccyx) LNP 

8. Stage I pressure ulcer (heel) LP

9. Stage I pressure ulcer (sacrum) LP

10. Stage I pressure ulcer (sacrum and buttocks) LP

11. Stage I pressure ulcer (unspecified location) LP 

12. Stage I pressure ulcer secondary to restraints (sacrum and buttock) LP 

13. Stage II pressure ulcer (buttock) LP 

14. Stage II pressure ulcer (buttock) LP 

15. Stage II pressure ulcer (buttock) UTD

16. Stage II pressure ulcer (heel and ankle) LP 

17. Stage II pressure ulcer (sacrum) CNP

18. Stage II pressure ulcer (sacrum) and stage I pressure ulcer (heel) LNP

19. Stage II pressure ulcer (unspecified location) LP 

20. Unstaged pressure ulcer (sacrum) LNP

IV volume overload (15)

1. Anasarca secondary to IV fluid resuscitation LNP 

2. Bilateral pulmonary effusion and pulmonary edema secondary to IV volume overload LP

3. Cascade event in which excessive IV fluids administered after a procedure led to 

volume overload and hyponatremia LP

4. Cascade event in which IV volume overload during a procedure led to acute respiratory 

distress LP

5. Cascade event in which the delay of a procedure led to the transfusion of additional 

blood products and resulted in dyspnea UTD 

6. Dyspnea and pulmonary congestion secondary to IV volume overload LNP 

7. Dyspnea and pulmonary edema secondary to IV volume overload of contrast agent LP

8. Dyspnea and pulmonary edema secondary to IV volume overload LP

9. Dyspnea secondary to fluid overload of contrast agent used during arteriogram LNP 

10. Dyspnea secondary to IV volume overload of fluids to correct bowel obstruction LP

11. Postoperative congestive heart failure secondary to IV volume overload LNP

12. Pulmonary edema secondary to IV volume overload LP 

13. Pulmonary edema secondary to postoperative IV volume overload LNP

14. Vascular congestion secondary to fluid resuscitation LNP

15. Vascular congestion secondary to IV volume overload of fresh frozen plasma LP 

Skin tear, laceration, abrasion, or other breakdown (9)

1. Blisters from telemetry leads (chest) CP 

2. Laceration during transfer to CT table (ankle) CP

3. Skin abrasion from tape removal (IV site) CNP 

4. Skin breakdown with inflammation and drainage (upper arm) LNP 

5. Skin breakdown with tear (sacrum) LP

6. Skin tear (elbow) LNP 

7. Skin tear (wrist) LNP 

8. Skin tear from prosthesis (heel) LNP 

9. Skin tears from patient turning (elbow and hand) LNP 

continued on next page 

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APPENDIX ~ H 

Table H-2: Temporary Harm Events, E Level on the NCC MERP Index, Identified 

Among Medicare Beneficiaries by Clinical Category (n=174) (Continued) 

Temporary Harm Event Preventability 

Events Related to Patient Care (continued)

IV infiltrate with symptoms (6)

1. Cellulitis secondary to IV infiltrate LNP 

2. IV infiltrate with pain and inflammation LNP 

3. IV infiltrate with pain and inflammation LNP 

4. IV infiltrate with pain, inflammation, and edema LNP 

5. Superficial phlebitis secondary to IV infiltrate LP

6. Thrombophlebitis secondary to IV infiltrate UTD 

Patient fall with injury (5)

1. Arm and shoulder injury resulting from patient fall LP 

2. Chest injury resulting from patient fall LNP 

3. Shoulder contusion and delay in surgery resulting from patient fall LNP 

4. Skin tear/abrasion on knees resulting from patient fall CP

5. Status epilepticus resulting from patient fall with head trauma LP

Aspiration (3)

1. Aspiration associated with endotracheal tube leak LNP 

2. Aspiration associated with procedure-related infiltrate LP

3. Aspiration pneumonitis associated with patient’s secretions CNP 

Failure to treat constipation or obstipation (3)

1. Exacerbation of constipation (impaction) secondary to narcotic analgesic 

(hydromorphone) due to failure to provide sufficient treatment LP 

2. Exacerbation of constipation secondary to increase in narcotic analgesics (unspecified) 

due to failure to provide sufficient treatment LP

3. Extended period of constipation due to failure to provide sufficient treatment LP

Tachycardia or dysrhythmia (2)

1. Nonsustained ventricular tachycardic dysrhythmia LP 

2. Paroxysmal supraventricular tachycardia UTD 

Events Related to Surgery or Other Procedures (32)

Urinary retention (8)

1. Postoperative urinary retention associated with indwelling catheter CNP 

2. Postoperative urinary retention associated with indwelling catheter LP

3. Postoperative urinary retention associated with indwelling catheter LP

4. Postoperative urinary retention associated with straight catheter LNP 

5. Postoperative urinary retention associated with straight catheter CNP 

6. Postoperative urinary retention following back surgery LNP 

7. Postoperative urinary retention following hip surgery LNP 

8. Postoperative urinary retention following hip surgery LNP 

Excessive bleeding (6)

1. Anemia following hip surgery LNP 

2. Bleeding from femoral catheter site LNP 

3. Bleeding from femoral catheter site following dialysis LNP 

4. Hematoma and bleeding from IV site LP

5. Hematoma and drop in hemoglobin following hip surgery LNP 

6. Hematoma secondary to IV extravasation LNP 

Cardiac complication (4)

1. Atrial fibrillation and palpitations following thoracotomy CNP 

2. Atrial fibrillation following cystoscopy LNP 

3. Minor myocardial infarction following neck surgery CNP 

4. Paroxysmal supraventricular tachycardia following surgery LNP 

continued on next page 

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APPENDIX ~ H 

Table H-2: Temporary Harm Events, E Level on the NCC MERP Index, Identified 

Among Medicare Beneficiaries by Clinical Category (n=174) (Continued) 

Temporary Harm Event Preventability 

Events Related to Surgery or Other Procedures (continued)

Surgical tear or laceration (3)

1. Dural tear during discectomy and spinal decompression LNP 

2. Dural tear during laminectomy LNP 

3. Unintentional enterotomy during surgery to relieve bowel obstruction LNP 

Urinary catheter-related trauma (3)

1. Hematuria associated with indwelling urinary catheter LNP 

2. Postoperative hematuria associated with indwelling urinary catheter CNP 

3. Postoperative hematuria associated with indwelling urinary catheter LNP 

Prolonged nausea and vomiting (2)

1. Prolonged nausea and vomiting following spinal surgery LNP 

2. Prolonged nausea and vomiting secondary to anesthetic given for dilation and curettage CNP 

 Postoperative or postprocedural hypotension (2)

1. Hypotension following cardiac procedure LP 

2. Hypotension following nephrectomy LNP 

Respiratory complication (2)

1. Dyspnea following nephrectomy UTD 

2. Hypoxemia following shoulder arthroplasty UTD 

 Other events related to surgery or other procedures (2)

1. Gout following pacemaker placement procedure CNP 

2. Ileus following hip arthroplasty LNP 

Events Related to Infection (6)

Surgical site infection (2)

1. Surgical site infection following colostomy procedure LNP 

2. Surgical site infection following hip surgery LP

Bacterial infection (1)

1. Bacterial parotiditis (glandular) infection LNP 

Respiratory infection (1)

1. Postoperative pneumonia LNP 

Urinary tract infection (1)

 1. Urinary tract infection related to urostomy LNP 

Vascular catheter-associated infection (1)

1. Infectious phlebitis at catheter insertion site LP 

Source: OIG analysis of hospital stays for 780 Medicare beneficiaries in October 2008.

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A P PEN 0 x 


Agency Comments: Agency for Healthcare Research and Quality 

DEPARTMENT OF HEALTH AND HUMAN SERVICES 	 Agency for Healthcar. 

Research and Quality 

540 Gaither Road 

Rockville, MD 20850 SEP 2 2 2010 www.ahrq.gov 

TO: 	 Daniel R, Levinson 


Inspector General 


FROM: 	 Carolyn M. Clancy, MD 


Director 


SUBJECT: 	 AHRQ Response to OIG draft report, Adverse Events in Hospitals: National Incidence 

Among Medicare Beneficiaries, OEI-06-09-00090. 

Thank you for the opportunity to review your draft report, Adverse Events in Hospitals: National 

Incidence Among Medicare Beneficiaries, OEI-06-09-00090 . .The findings in the report are consistent 

with previous studies but are nonetheless disturbing. They confirm that adverse events continue to 

affect hospital inpatients at an alarming rate, and that the types of events that occur vary widely, The 

report reaffirms AHRQ's need to continue work on improving patient safety by broadening investigation 

to include areas that are not always seen on lists of adverse events that should never occur or should 

always be reported. 

Responses are provided below to the report's two general recommendations that pertain to AHRQ and 

were provided in the July 20, 2010, draft version of the report that the Agency reviewed. AHRQ concurs 

with both OIG recommendations. . 

Recommendation: AHRQ and CMS should broaden patient safety efforts to include all types of adverse 

events. 

AHRQ Response: CONCUR 

AHRQ agrees that efforts to improve patient safety should be broad. While we have sponsored efforts 

to address specific types of adverse events, such as central-line-associated bloodstream infections and 

venous thromboembolisms, we have also supported efforts to address underlying causes that 

contribute to a wide variety of adverse events. For example, we have focused on improving the safety 

culture in healthcare by providing a widely-adopted patient safety culture survey that is used by 

hospitals and healthcare systems, and by providing team training to healthcare systems via the 

TeamSTEPPS program that we developed in concert with the Department of Defense. We have also 

provided broad in-person training on the topic of patient safety improvement to public sector and 

private sector representatives from every state via the Patient Safety Improvement Corps, which we 

implemented in concert with the Department of Veterans Affairs' National Center for Patient Safety. As 

we continue to lead and support Federal efforts in patient safety improvement, we intend to broaden 

efforts to improve patient safety overall (as with TeamSTEPPS), and to address specific problems, such 

as a targeted program to foster the widespread implementation of the CDC's guideline to prevent 

catheter-associated urinary tract infections. 

1 

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APPEND X 

Agency Comments: Centers for Medicare & Medicaid Services 

/$.U.Vlcq.~ (-I.. DEPARTMENT OF HEALTH & HUMAN SERVICES Center. for Medicare & Medicaid Servicas 

,,~~~ ....... (; 
 Administrator 

Washington, DC 20201 

SEP 0 92010 DATE: 

TO: Daniel R. Levinson 	 ,..." 

'= Inspector General ~";) 

C/) ')

Cl' ", -u '1 FROM: ""'11' ..

:1':" ) 

",. 

n:. W '~1 

Thank. you for the opportunity to review and comment on the subject OIG Draft Report, 

"Adverse Events in Hospitals: National Incidence Among Medicare Beneficiaries, OEI-06-09­

00090." We appreciate the OIG's work on this important and timely topic. When one in eight 

hospitalized Medicare beneficiaries experience an adverse event, most ofwhich result in a 

prolonged hospital stay, permanent harm, life-saving interventions, or death, solutions need to be 

addressed as quickly and efficiently as possible. The Centers for Medicare & Medicaid Services 

(CMS) has taken significant steps to address these issues, but more work needs to be done. 

The report's findings provide new information to the Department of Health and Human Services 

(HHS) broadly, and the Centers for Medicare & Medicaid Services (CMS) specifically, upon 

which to act to expand efforts to work with hospitals and clinicians to prevent adverse events. 

CMS seeks to promote a culture of safety across the country in all health care settings. While the 

report characterizes CMS as an oversight entity and the nation's largest health payer, CMS is 

also actively transitioning from serving solely as a regulator and passive payer of health care 

services to an agency that fully supports public health goals as an active payer of high quality 

and efficient care. 

CMS is also an engine for innovation across health care. Several new legislative and regulatory 

enarts, including the new Center for Medicare & Medicaid Il1novation, provide us with new and 

innovative tools to address the concerns raised in this report. In addition, we plan to continue 

several efforts already in progress to reduce adverse events. While this response focuses on 

adverse events in hospitalized patients, our efforts are also directed at addressing issues in 

dialysis centers and ambulatory and long term care settings, recognizing that in our dynamic and 

complex healthcare system a patient should expect and receive safe care, wherever that care may 

be provided. 

While we have a number of efforts already underway (as discussed throughout this response), we 

are launching a number of new efforts to infuse a cross-cutting theme of safety throughout the 

agency to promote a coordinated effort among existing and emerging programs. These are all 

designed to create incentives for and support to hospitals to identify adverse events, practices to 

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 ACKNOWLEDGMENTS 

This report was prepared under the direction of Kevin K. Golladay, 

Regional Inspector General for Evaluation and Inspections in the Dallas 

regional office, and A. Blaine Collins, Deputy Regional Inspector 

General. 

Amy Ashcraft and Ruth Ann Dorrill served as the team leaders for this 

study. Other principal Office of Evaluation and Inspections staff from 

the Dallas regional office who contributed to the report include Deborah 

Cosimo, Nathan Dong, Ben Gaddis, Jennifer Gist, Anthony 

Guerrero-Soto, Deborah McGurk, and Jeremy Moore; central office staff 

who contributed include Rob Gibbons, Sandy Khoury, Sue Nonemaker, 

Arianne Spaccarelli, and Rita Wurm. 
 

Office of Inspector General 

http://oig.hhs.gov 

The mission of the Office of Inspector General (OIG), as mandated by Public Law 95-452, as 

amended, is to protect the integrity of the Department of Health and Human Services 

(HHS) programs, as well as the health and welfare of beneficiaries served by those 

programs. This statutory mission is carried out through a nationwide network of audits, 

investigations, and inspections conducted by the following operating components: 

Office of Audit Services 

The Office of Audit Services (OAS) provides auditing services for HHS, either by conducting 

audits with its own audit resources or by overseeing audit work done by others. Audits 

examine the performance of HHS programs and/or its grantees and contractors in carrying 

out their respective responsibilities and are intended to provide independent assessments of 

HHS programs and operations. These assessments help reduce waste, abuse, and 

mismanagement and promote economy and efficiency throughout HHS. 

Office of Evaluation and Inspections 

The Office of Evaluation and Inspections (OEI) conducts national evaluations to provide 

HHS, Congress, and the public with timely, useful, and reliable information on significant 

issues. These evaluations focus on preventing fraud, waste, or abuse and promoting 

economy, efficiency, and effectiveness of departmental programs. To promote impact, OEI 

reports also present practical recommendations for improving program operations. 

Office of Investigations 

The Office of Investigations (OI) conducts criminal, civil, and administrative investigations 

of fraud and misconduct related to HHS programs, operations, and beneficiaries. With 

investigators working in all 50 States and the District of Columbia, OI utilizes its resources 

by actively coordinating with the Department of Justice and other Federal, State, and local 

law enforcement authorities. The investigative efforts of OI often lead to criminal 

convictions, administrative sanctions, and/or civil monetary penalties. 

Office of Counsel to the Inspector General 

The Office of Counsel to the Inspector General (OCIG) provides general legal services to 

OIG, rendering advice and opinions on HHS programs and operations and providing all 

legal support for OIG’s internal operations. OCIG represents OIG in all civil and 

administrative fraud and abuse cases involving HHS programs, including False Claims Act, 

program exclusion, and civil monetary penalty cases. In connection with these cases, OCIG 

also negotiates and monitors corporate integrity agreements. OCIG renders advisory 

opinions, issues compliance program guidance, publishes fraud alerts, and provides other 

guidance to the health care industry concerning the anti-kickback statute and other OIG 

enforcement authorities.