Department of Health and Human Services

OFFICE OF 

INSPECTOR GENERAL 

 

Daniel R. Levinson 

Inspector General 

December 2008 

OEI-06-08-00220 

 

ADVERSE EVENTS IN HOSPITALS: 

CASE STUDY OF INCIDENCE 

AMONG MEDICARE 

BENEFICIARIES IN TWO 

SELECTED COUNTIES 
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 hospitalizations involving HHS programs, including False 

Claims Act, program exclusion, and civil monetary penalty hospitalizations. In connection 

with these hospitalizations, 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. 
 

Δ EXECUTIVE SUMMARY 

OBJECTIVE

To estimate the incidence of adverse events for hospitalized Medicare 

beneficiaries in two selected counties. 

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 healthcare setting.” The Tax Relief 

and Health Care Act of 2006 (the Act) mandates that the Office of 

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

never events among Medicare beneficiaries, payment by Medicare or 

beneficiaries for services in connection with such events, and Centers 

for Medicare & Medicaid Services (CMS) processes to identify events 

and deny payment. This report is one in a series to fulfill requirements 

in the Act. OIG work on this topic will continue through 2009. 

We reviewed a random sample of 278 hospitalized Medicare 

beneficiaries selected from all beneficiaries hospitalized in two selected 

counties during a 1-week period in August 2008. Physician reviewers 

determined whether an adverse event occurred, whether the event was 

on NQF’s list of Serious Reportable Events or CMS’s list of 

hospital-acquired conditions, and the level of harm to the patient based 

on an established harm scale. To establish an estimated adverse event 

incidence rate, we included events on the NQF and CMS lists and also 

events resulting in the most serious categories on the harm scale 

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

or death). We also determined whether events on the NQF and CMS 

lists caused higher Medicare reimbursement. Lastly, we identified 

additional events that resulted in temporary patient harm but were not 

comparable to the more serious events in our overall rate. 

FINDINGS 

Fifteen percent of hospitalized Medicare beneficiaries in two 

selected counties experienced an adverse event during their 

hospital stays. Of the 278 Medicare beneficiaries in our sample, 

41 experienced an adverse event during their hospital stay that met one 

or more of our three criteria for an estimated adverse event rate of 

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EXECUTIVE SUMMARY 

15 percent. Six of these forty-one patients experienced multiple adverse 

events, for a total of 51 adverse events. Incidence rates for adverse 

events that met our three criteria were as follows: fewer than 1 percent 

of beneficiaries experienced an adverse event on NQF’s list of Serious 

Reportable Events, 4 percent experienced an adverse event on CMS’s 

list of hospital-acquired conditions, and 13 percent experienced an 

adverse event resulting in the four most serious categories on the 

patient harm scale. (Some adverse events met more than one criterion.) 

Of adverse events on CMS’s list of hospital-acquired conditions and 

NQF’s list of Serious Reportable Events, only one resulted in higher 

Medicare reimbursement to the hospital. 

Identified adverse events illustrate differences in the lists and 

criteria that define adverse events. A difficulty in determining 

adverse events incidence rates involves differences in the definitions 

used by various entities. The NQF list of Serious Reportable Events 

and the CMS list of hospital-acquired conditions often address the same 

adverse event but define the event differently. For example, our sample 

included two adverse events involving poor glycemic control, both of 

which resulted in serious harm. However, because of differences in the 

way specific adverse events are defined, one case met the criteria of 

NQF’s list and the other met the CMS criteria. 

An additional 15 percent of Medicare beneficiaries in the two 

selected counties experienced events during their hospital stays 

that resulted in temporary harm. In addition to the adverse events 

previously discussed, another 15 percent of Medicare beneficiaries 

experienced events classified as temporary harm requiring medical 

intervention. This category of harm represents a wide array of events, 

from swelling at a treatment site to low-level infections. In some cases, 

the events resulted from standard medical treatment that caused an 

undesirable outcome in the patient, such as an allergic reaction to 

medication. Because these temporary events did not prolong the 

hospital stay or result in permanent harm, they are not included in our 

overall rate of adverse events. However, these events are of interest to 

hospitals and others seeking to improve patient safety because they are 

potential indicators of patient care problems and/or improvement 

opportunities. For a number of these patients, physician reviewers 

indicated that these temporary harm events could have developed into 

more serious adverse events with a greater degree of harm without 

timely intervention. 

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EXCUTIVE SUMMARY 

CONCLUSION 

The Act requires that OIG report to Congress regarding harm caused in 

health care settings. This study is one of several designed to meet this 

mandate, providing an estimate of the incidence of adverse events 

among hospitalized Medicare beneficiaries in two selected counties. 

Although these results are not nationally representative, the extent of 

adverse events and temporary harm found in this case study 

substantiates concerns about the incidence of adverse events in 

hospitals and the importance of safety initiatives to reduce occurrences. 

Our analysis also calls attention to the difficulty of determining what 

events should be considered in an adverse event incidence rate and how 

those events should be identified and defined. 

The Act also directs OIG to make recommendations for such legislation 

and administrative action as OIG determines is appropriate. The Act 

specifically authorized funding to continue through calendar year 2009 

and OIG will devote this funding to additional studies involving adverse 

events. Future reports in this series will include recommendations as 

appropriate. 

AGENCY COMMENTS AND OFFICE OF INSPECTOR GENERAL 

RESPONSE 

We received positive comments on a draft of this report from the Agency 

for Healthcare Research and Quality and from CMS. CMS reiterated its 

policies to encourage the prevention of adverse events, including the 

provision to deny payment for care associated with hospital-acquired 

conditions, and indicated that OIG identification of hospital-acquired 

conditions and their effect on Medicare payment allowed for a deeper 

understanding of the payment policy in practice. CMS also offered 

clarification regarding one of the hospital-acquired conditions, catheterassociated urinary tract infection, and recommended further evaluation 

of this issue. OIG agrees that further evaluation is warranted and will 

address this issue in future work in this series. 
Δ TABLE OF CONTENTS 

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

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

FINDINGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 

 Fifteen percent of beneficiaries experienced an adverse event . . . 10 

 Identified adverse events illustrate differences in definitions . . . 15 

 Beneficiaries had additional events causing temporary harm . . . 16 

CONCLUSION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 

 Agency Comments and Office of Inspector General Response . . . 20 

APPENDIXES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 

 A: Tax Relief and Health Care Act of 2006 . . . . . . . . . . . . . . . . . . 21 

 B: Glossary of Selected Terms . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 

 C: National Quality Forum Serious Reportable Events . . . . . . . . 26 

D: Centers for Medicare & Medicaid Services Categories of 

Hospital-Acquired Conditions . . . . . . . . . . . . . . . . . . . . . . . . . 27 

 E: Detailed Methodology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 

 F: Estimates and Confidence Intervals . . . . . . . . . . . . . . . . . . . . . 33 

G. Tables of All Adverse Events and Temporary Harm Events 

Identified in Sample . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 

 H: Agency Comments. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 

ACKNOWLEDGMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Δ INTRODUCTION 

OBJECTIVE 

To estimate the incidence of adverse events for hospitalized Medicare 

beneficiaries in two selected counties. 

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) study events that cause harm to 

Medicare beneficiaries. The Act specifically mandates that OIG study 

the incidence of “never events” among Medicare beneficiaries, payment 

by Medicare or beneficiaries for services furnished in connection with 

such events, and administrative processes of the Centers for Medicare & 

Medicaid Services (CMS) to identify events and deny or recoup 

payment. OIG is also to report to Congress on the study conducted, 

including recommendations for such legislation and administrative 

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

see Appendix A.) 

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. In 2006, 12.5 million Medicare beneficiaries were 

hospitalized,1 with inpatient hospital costs constituting the largest 

portion of Medicare expenditures (32 percent in 2006).2 Government 

agencies and private entities have also targeted hospitals for 

patient-safety initiatives. 

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

health care events that result in patient harm. (For a glossary of 

selected terms, see Appendix B.) The National Quality Forum (NQF) 

used the term “never event” to describe a specific list of events 

associated primarily with patient death or serious disability that 

1 CMS, “Statistics Book,” Table IV.1: Medicare/short-stay hospital utilization, 2008, 

p. 43. Available online at 

http://www.cms.hhs.gov/CapMarketUpdates/Downloads/2008CMSStats_xls.pdf. Accessed 

on November 12, 2008. 

2 Based on data contained in the Congressional Budget Office (CBO), “Fact Sheet for 

CBO’s March 2007 Baseline: Medicare,” March 7, 2007. Available online at 

http://www.cbo.gov/budget/factsheets/2007b/medicare.pdf. Accessed on September 8, 2008. 

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INTRODUCTION 

“should never occur in a health care setting.”3 NQF currently uses the 

term “Serious Reportable Events” to describe this list. (For a list of 

NQF Serious Reportable Events, see Appendix C.) Since enactment of 

the Act, patient safety issues have continued to receive much attention 

by policymakers, the health care industry, and patient advocates. The 

term “adverse events” is now used more commonly than never events 

within the health care community to refer to harm experienced by a 

patient as a result of medical care. As a result, and after consulting 

with selected congressional committee staff in 2007, OIG modified our 

approach and terminology to be consistent with evolving patient safety 

research and industry trends. In doing so, we expanded our focus 

beyond the list of 28 never events specified by NQF to a broader view of 

adverse events causing harm to patients. 

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

medical care. Although an adverse event indicates that the care 

resulted in an undesirable clinical outcome and may involve medical 

errors, adverse events do not always involve errors, negligence, or poor 

quality of care and may not always be preventable.4 As such, research 

and policy to ensure patient safety and reduce the occurrence of adverse 

events often focuses on identifying and addressing systemic problems 

that may lead to patient harm and avoids labeling the event as an 

outcome of negligence or poor quality. 

2 

This broad definition of adverse events reflects not only a variety of 

possible causes of events, but also a wide range in their effect on 

patients. Depending on their purpose, 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. For example, NQF’s 

list of Serious Reportable Events focuses on events that cause serious 

disability and death. The National Coordination Council for Medication 

Errors Reporting and Prevention (NCC MERP) developed a scale to 

categorize the level of patient harm resulting from medication errors. 

The NCC MERP Index for Categorizing Errors considers factors such as 

whether the occurrences had any effect on the patient and, if so, the 

degree of harm (see Table 1). The scale includes categories for 

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

national strategy for health care quality measurement and reporting. The list is available 

online at http://www.qualityforum.org/about. Accessed on October 21, 2008. 

4 R.M. Wachter, “Understanding Patient Safety,” McGraw-Hill, 2008. 

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INTRODUCTION 

circumstances or occurrences wherein harm did not reach the patient 

(categories A-D), often referred to as “near misses,” and those wherein 

the patient was actually harmed (categories E-I). Researchers have 

modified this scale for use in measuring and distinguishing adverse 

events of all types, rather than only medication errors.5 

Table 1: The National Coordinating Council for Medication Errors 

Reporting and Prevention Index for Categorizing Errors 

Category Description Event 

A Circumstances or events occur that have the capacity 

to cause error. 

B An error occurred, but the error did not reach the 

patient. 

C An error occurred that reached the patient, but did not 

cause patient harm. 

D 

An error occurred that reached the patient and 

required monitoring to confirm that it resulted in no 

harm to the patient, and/or required intervention to 

preclude harm. 

Harm does 

not reach 

patient 

E 

An error occurred that may have contributed to or 

resulted in temporary harm to the patient and required 

intervention. 

F 

An error occurred that may have contributed to or 

resulted in temporary harm to the patient and required 

an initial or prolonged hospital stay. 

G An error occurred that may have contributed to or 

resulted in permanent patient harm. 

H An error occurred that required intervention necessary 

to sustain life. 

I An 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.

Medicare Payment for Adverse Events 

Medicare traditionally did not distinguish between costs incurred for 

treating existing illnesses and those incurred as the result of adverse 

events. Medicare reimbursement to inpatient acute care hospitals is 

generally determined by grouping patient conditions into 

Diagnosis-Related Groups (DRG) based on the average cost of care for 

patients with similar conditions. Historically, if a Medicare beneficiary 

experienced harm from an adverse event that resulted in assignment of 

3 

5 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. 

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INTRODUCTION 

a more expensive DRG, CMS paid the full claim without any payment 

reduction.6 

Hospital-Acquired Conditions. The Deficit Reduction Act of 2005 (DRA) 

required CMS to select at least two hospital-acquired conditions for 

which hospitals would not be paid higher Medicare reimbursement.7 

CMS issued a final regulation in August 2007 allowing it to deny 

hospitals higher payment for admissions complicated by any of eight 

categories of hospital-acquired conditions. CMS chose the categories of 

conditions in collaboration with the Centers for Disease Control and 

Prevention and used 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.8 

In July 2008, CMS issued a final rule expanding the list of 

hospital-acquired conditions to 10. Effective October 1, 2008, CMS 

began denying hospitals higher payment for Medicare admissions 

complicated by these conditions.9 For the list of CMS categories of 

hospital-acquired conditions, see Appendix D. 

Changes to CMS Payment. In addition to designating the list of 

hospital-acquired conditions, the FY 2008 Inpatient Prospective 

Payment System 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 individual classes based 

6 U.S. Department of Health and Human Services, CMS, Press Release, “Eliminating 

Serious, Preventable, and Costly Medical Errors – Never Events,” May 18, 2006. Available 

online at http://www.cms.hhs.gov/apps/media/press/release.asp?Counter=1863. Accessed on 

August 28, 2008. 

7 DRA, § 5001(c), P.L. No. 109-171 (adding Social Security Act, § 1886(d)(4)(D); 

42 U.S.C. § 1395ww(d)(4)(D)), provided for a quality adjustment in DRG payments for 

certain hospital-acquired conditions. 

8 Social Security Act, § 1886(d)(4)(D)(iv); Fiscal Year (FY) 2008 Final Inpatient 

Prospective Payment Systems (IPPS) Rule, 72 Fed. Reg. 47130, 47202 (Aug. 22, 2007). 

9 Social Security Act, § 1886(d)(4)(D)(i); FY 2009 Final IPPS Rule, 73 Fed. Reg. 48434, 

48471—48472 (Aug. 19, 2008). 

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 INTRODUCTION INTRODUCTION 

on the presence of a complication or comorbidity.10 Beginning 

October 1, 2007, each medical diagnosis (ICD-9-CM) code11 submitted 

must include a new indicator designating whether the condition is 

present on admission (POA).12 

Determining the Incidence of Adverse Events in Hospitals 

Research indicates that calculating the incidence of adverse events is a 

complex and difficult task and that no single method is likely to identify 

all adverse events.13 Further, researchers often use different definitions 

and methods, making comparison of adverse event incidence rates 

problematic. Through a literature review, we identified the following 

prominent methods for identifying adverse events in hospitals: 

Patient Survey or Interview. A number of studies have sought to identify 

adverse events by asking patients and their families whether they 

detected any problems during their hospital stays, typically through 

interviews or mail surveys. This information is considered most useful 

when patients or families are asked about events shortly after they 

occur. Disadvantages associated with patient surveys include low 

response rates, poor recollection by patients, and lack of understanding 

of adverse events or the expected course of treatment. 

Administrative Data Screening. Automated programs can be used to 

review administrative data, such as payment claims and hospital 

discharge data, to identify possible adverse events. Using 

administrative data allows researchers to screen for adverse events 

among large numbers of hospitalizations. Prominent administrative 

data screening methods include: 

• Patient Safety Indicators (PSI) Algorithms: AHRQ developed 

software programs to calculate PSIs using administrative data and 

distributes this software free of charge to hospitals and researchers. 

The software is based on a series of algorithms using data commonly 

available in administrative datasets, such as billing data. These 

10 42 CFR § 412.10; Final FY 2008 IPPS Rule, 72 Fed. Reg. 47130, 47138 (Aug. 22, 2007). 

11 The ICD-9-CM system assigns diagnoses and procedure codes associated with 

hospitalizations and is maintained jointly by the National Center for Health Statistics 

(NCHS) and CMS. NCHS, “The International Classification of Diseases, 9th Revision, 

Clinical Modification” (ICD-9-CM), Sixth Edition, was issued for use beginning 

October 1, 2007. 

12 Social Security Act, § 1886(d)(4)(D)(iii). 

13 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. 

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INTRODUCTION 

algorithms detect indicators (e.g., death in a low-risk patient) to help 

identify potential adverse events. 

• Identification of POA Indicators: POA codes were added as a 

requirement for Medicare billing data in August 2007 to facilitate 

CMS’s implementation of the new policy for nonpayment of certain 

hospital-acquired conditions. Hospitals include these indicators 

with each diagnosis code, allowing analysts to identify conditions 

that developed during the hospital stay. 

Review of In-Hospital Incident Reports. Hospitals must measure, analyze, 

and track quality indicators, including adverse patient events, as a 

condition of participation for Medicare and Medicaid certification.14 To 

accomplish this, hospital staff typically complete “in-house incident 

reports” when notable events occur. For example, a hospital may 

require staff to complete an incident report if a patient falls. Hospital 

managers can use information contained in incident reports to gain 

awareness of quality improvement needs and address substandard care. 

Although incident reports are likely a valuable source of information, 

research indicates that not all events are reported. 

Medical Record Screening. Although it is not a complete medical record 

review, medical record screening can identify potential adverse events 

based on information in the medical record. One prominent screening 

tool, the Institute for Healthcare Improvement (IHI) Global Trigger Tool 

(GTT), uses a retrospective review of medical records to identify 

“triggers” that could signal patient harm.15 The GTT also categorizes 

the level of harm using the NCC MERP patient harm scale. The 

purpose of the NCC MERP index is to track errors in a consistent, 

systematic manner.16 IHI adapted the index for use as part of the 

GTT to classify harm associated with adverse events. 

Medical Record Review. Medical record review is often considered the 

most definitive method for detecting adverse events because it can 

provide much detail about both the adverse event and the surrounding 

14 42 CFR § 482.21(a)(2). 

15 Some triggers are adverse events by definition. Additionally, reviewers may identify 

adverse events without a trigger and may find triggers that are not adverse events. 

16 NCC MERP, Press Release. “Medication Errors Council Revises and Expands Index 

for Categorizing Medication Errors: Definitions of Medication Errors Broadened,” June 12, 

2001. Available online at http://www.nccmerp.org/press/press2001-06-12.html#index. 

Accessed on October 14, 2008. 

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INTRODUCTION 

circumstances. For example, medical record reviews can provide 

information about the patient’s condition prior to and following the 

event. However, researchers report that records often have incomplete 

descriptions and insufficient documentation.17 Also, record reviews rely 

on the subjective judgment of the reviewer, and conditions caused by 

adverse events can be difficult to distinguish from preexisting or 

unpreventable conditions. 

METHODOLOGY 

Scope 

In this report, we provide an estimated rate of adverse events for 

Medicare beneficiaries discharged from hospitals in two counties during 

a 1-week period in August 2008, as well as specific rates of incidence for 

adverse events included on NQF’s and CMS’s lists. To determine a 

meaningful rate of adverse events, we incorporated criteria developed 

by NQF, CMS, and NCC MERP. We included in our analysis all patient 

harm that occurred during the hospitalization, regardless of whether it 

was preventable. We conducted these activities during August–October 

2008. For a detailed description of our methodology, see Appendix E. 

Sample Selection 

To determine adverse event incidence rates, we sampled Medicare 

hospital discharges within two counties in different States.18 From each 

of the population of 24 hospitals in the two counties, we obtained lists of 

all Medicare-enrolled beneficiaries who were discharged during the 

week of August 10–16, 2008. From a combined list of 2,549 hospital 

discharges, we randomly selected a total of 310 Medicare 

hospitalizations. Unless otherwise noted, results in this report are 

projected to all eligible discharges from the 24 hospitals during the 

sampled week. We determined that 32 sample hospitalizations were 

ineligible for review, typically because the Medicare beneficiary was not 

an inpatient for at least 24 hours. A total of 278 sample hospitalizations 

met our criteria for review and are the focus of this report. Among 

the 278 Medicare beneficiaries in the sample, the average age was 

17 M.M. Rosenthal, P.L. Cornett, K.M. Sutcliffe, and E. Lewton, “Beyond the Medical 

Record: Other Modes of Error Acknowledgment,” Journal of General Internal Medicine, 

20(5), May 2005, pp. 404–409. Abstract available online at 

http://www.ncbi.nlm.nih.gov/pubmed/15963161. Accessed on October 10, 2008. 

18 Because the Act stipulates that OIG shall not release facility-specific information, we 

do not name the counties in this report. 

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INTRODUCTION 

77 years, with a range of 24 to 102 years; and the average length of 

hospitalization was 6 days, with a range of 1 to 53 days. 

Analysis 

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

stage included five distinct screening processes designed to identify 

sampled hospitalizations that appeared likely to include an adverse 

event. The screening processes included: 

• beneficiary interviews, 

• administrative data screening using AHRQ’s PSI program, 

• analysis of POA indicators included in administrative billing data, 

• reviews of hospital incident reports related to the hospitalization, 

and 

• targeted medical record screening using the IHI GTT protocol. 

For the second stage of review, we included only hospitalizations with 

potential adverse events flagged by one or more of these screening 

processes. This stage consisted of a full physician review of the medical 

record. The use of multiple screening processes allowed us to test the 

utility of various screening methods in preparation for future work to 

determine a national adverse events incidence rate. The screening 

processes also allowed us to reduce the number of hospitalizations 

requiring medical record review by a physician. 

In the second stage of review, contracted physicians conducted an onsite 

medical review (183 hospitalizations were flagged for this stage of 

review). The medical review protocol included a review of the 

information from the five screening processes for the flagged 

hospitalizations and the full medical record. Physician reviewers 

completed a structured medical review protocol that required them to 

describe the adverse event, the documentation that led to their 

identification of the event, and the level of harm to the patient using the 

NCC MERP harm scale. We include in this report only adverse events 

identified or confirmed by the physician reviewers. 

Based on the results of the physician medical record review, we 

calculated adverse event incidence rates as the proportion of Medicare 

beneficiaries with at least one qualifying adverse event. To calculate an 

overall adverse event incidence rate, we focused on the areas of interest 

outlined in the Act: serious adverse events that may have payment 

implications for Medicare or beneficiaries. Therefore, we calculated an 

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INTRODUCTION 

overall adverse event incidence rate to include events meeting any of 

the following criteria: 

1. NQF’s list of Serious Reportable Events, as the Act mandates; 

2. CMS’s list of hospital-acquired conditions; and 

3. level of patient harm determined by physicians to have resulted in 

a prolonged hospital stay, permanent harm, life-sustaining 

intervention, or death (classified as F–I on the NCC MERP scale).

This overall adverse event incidence rate does not include events that 

physician reviewers identified as temporary harm events (classified as 

E-level of harm on the NCC MERP scale). 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 these temporary 

harm events, as well as separate rates for the NQF list, the CMS list, 

and the events classified as F-I on the NCC MERP scale. 

We also analyzed administrative billing data for adverse events that 

were included on NQF’s or CMS’s list. We calculated the effect of 

adverse events on Medicare payment using CMS’s MS-DRG Assignment 

with Medicare Code Editor V25. We did not calculate the effect on 

Medicare payment for adverse events not on the CMS or NQF lists. 

Limitations 

Findings from this study are limited to the particular geographic area 

and timeframe covered by our review and cannot be generalized to the 

Medicare population at large. Further, it is unlikely that our 

methodology identified all adverse events within our sample. The 

screening processes may have failed to flag adverse events and we 

included adverse events only when the medical record confirmed the 

event. In some cases, missing information in medical records, if 

available, may have identified additional instances of adverse events. 

Quality Standards 

This study was conducted in accordance with the “Quality Standards for 

Inspections” issued by the President’s Council on Integrity and 

Efficiency and the Executive Council on Integrity and Efficiency. 

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Of the 278 Medicare beneficiaries in 

our sample, 41 experienced an 

adverse event during their hospital 

stays that met at least one of our 

criteria: events on NQF’s list of Serious Reportable Events, events on 

CMS’s list of hospital-acquired conditions, or events involving a 

prolonged hospital stay, permanent harm, life-sustaining intervention, 

or death (classified as F-I on the NCC MERP scale). This overall rate 

does not include events that cause only temporary harm to patients 

because we determined these events were not comparable to the more 

serious events included in the rate. 

Fifteen percent of hospitalized Medicare beneficiaries 

in two selected counties experienced an adverse event 

during their hospital stays 

Δ FINDINGS 

After applying statistical methods, we project an estimated 15 percent 

adverse event incidence rate for the two counties (see Appendix F for 

confidence intervals). Six of these forty-one hospital patients 

experienced multiple adverse events, for a total of 51 adverse events. 

Table 2 lists the number of events, number of affected Medicare 

beneficiaries, and incidence rate for each of the three criteria. 

Table 2: Incidence of Adverse Events Among Medicare Beneficiaries in Two 

Selected Counties 

Sample Projected 

Category of Events 

Number of 

Identified 

Events 

Number of 

Medicare 

Beneficiaries 

Percentage 

of Medicare 

Beneficiaries 

NQF Serious Reportable Events 3 2 0.7% 

CMS Hospital-Acquired Conditions 11 10 3.7% 

NCC MERP F-I Level Events 43 36 13.2% 

(Overlapping Events)* (6) (7) (2.6%) 

 Total 51 41 15.0% 

Source: OIG analysis of 278 Medicare beneficiary hospitalizations in two selected counties, 2008. 

*Some adverse events met more than one criterion and overlap the three categories. 

We grouped the 51 adverse events into four broad categories: 

complications associated with surgery or other hospital procedures 

(43 percent), hospital-acquired infections (35 percent), medicationrelated events (12 percent), and events related to patient care 

(10 percent). Table 3 lists the 51 adverse events by these four clinical 

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FINDINGS 

categories. For a list of all adverse events with more complete 

definitions and the associated level of harm, see Appendix G. 

Table 3: Adverse Events Identified Among Hospitalized Medicare 

Beneficiaries in Two Selected Counties by Type (n = 51) 

Types of Adverse Events 

Adverse Events 

and Percentage 

of Total Events 

Events Related to Surgery or Other Procedures 22 (43%) 

Excessive bleeding following surgery or procedure 4 

Respiratory complications related to surgery or procedure 4 

Postoperative ileus 4 

Cardiac complications related to surgery or procedure 3 

Hypotension/blood loss 3 

Blood clots and other occlusions related to surgery or procedure 2 

Post colostomy bowel obstruction 1 

Premature extubation causing respiratory failure 1 

Hospital-Acquired Infections 18 (35%) 

Urinary tract infection associated with Foley catheter 6 

Surgical infection 3 

Respiratory infection (not ventilator associated) 3 

Central line infection 2 

Ventilator-associated pneumonia 2 

Gastrointestinal infection 1 

Sepsis as result of delay in performing surgery 1 

Events Related to Medication 6 (12%) 

Medication-related hypotension 2 

Medication-related delirium 1 

Medication-related gastrointestinal bleed 1 

Kidney damage because of use of contrast 1 

Medication-related acute renal insufficiency 1 

Events Related to Patient Care 5 (10%) 

Stage III pressure ulcer 2 

Stroke and resulting paralysis related to hypoglycemia 1 

Hypoglycemic coma 1 

Intravenous volume overload 1 

Source: OIG analysis of 278 Medicare beneficiary hospitalizations in two selected counties, 2008. 

Seven of the fifty-one adverse events in our sample were “cascade” 

events wherein an initial adverse event caused a series of additional, 

related events for the same patient. Our analysis grouped cascade 

events together into one adverse event. These cascade events were 

some of the most serious adverse events identified, with six of the seven 

cascade events identified resulting in life-sustaining intervention, 

serious disability or death. Six of the seven cascade events began as the 

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FINDINGS 

result of postsurgical complications. For example, one cascade event 

involved a patient undergoing surgery and developing a bowel 

obstruction postoperatively, which resulted in hypotension, excessive 

bleeding, and ultimately required both a blood transfusion and 

corrective surgery. Two of the postoperative cascades led to patient 

death; for example, one beneficiary experienced a series of postoperative 

events including renal and respiratory failure, and subsequently died of 

a heart attack. 

Fewer than 1 percent of Medicare beneficiaries in two selected counties 

experienced an event on the National Quality Forum list of Serious 

Reportable Events 

Two beneficiaries experienced an adverse event on the NQF list of 

Serious Reportable Events, and one of these beneficiaries experienced 

two events on the list. The three NQF events we identified involved two 

beneficiaries for an estimated incidence rate in the two counties of less 

than 1 percent (0.7 percent). Both of the beneficiaries developed 

Stage III pressure ulcers during their hospital stays. (Stage III 

pressure ulcers are defined as having both skin loss and damage to the 

tissue below the skin.19) In both cases, the pressure ulcers were 

classified by physician reviewers as constituting temporary harm 

because they did not prolong the hospital stay or cause permanent 

disability to the beneficiary. 

One of these two patients had a second adverse event on NQF’s list: 

serious patient disability resulting from poor glycemic control. NQF 

defines serious disability as loss of a body part, or disability or loss of 

bodily function lasting more than 7 days or still present at discharge.20 

In this case, the patient developed partial paralysis after experiencing a 

stroke associated with severe hypoglycemia. This same patient died as 

the result of another adverse event not on NQF’s list: septic shock 

caused by a bacterial infection. 

12 

19 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,” 

February 2007. Available online at http://www.npuap.org/pr2.htm. Accessed on 

November 18, 2008. 

20 NQF, “Serious Reportable Events in Healthcare 2006 Update: A Consensus Report,” 

NQF, Washington, DC. 2007, p. 7. Available online at 

http://www.qualityforum.org/pdf/reports/sre/txsrepublic.pdf. Accessed on October 10, 2008. 

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FINDINGS 

One of the three adverse events on NQF’s list resulted in a higher Medicare 

reimbursement. In this case, the Medicare beneficiary was a nursing home 

resident who developed a Stage III pressure ulcer during a 12-day hospital 

stay. Including the pressure ulcer on the list of billable diagnoses changed 

the MS-DRG from a class associated with lower-level complications or 

comorbidities to a class associated with major complications or 

comorbidities. We determined that this increased the Medicare 

reimbursement from $7,086 to $9,138, a difference of 

$2,052 or 29 percent.21 In the other two cases, the patients’ other 

complications or comorbidities increased reimbursement to the maximum 

allowed for the MS-DRG.

Four percent of Medicare beneficiaries in two selected counties experienced 

an event on CMS’s list of hospital-acquired conditions; in one case, the 

condition resulted in a higher Medicare reimbursement 

An estimated 3.7 percent of hospitalized Medicare beneficiaries in the 

two counties had an adverse event on CMS’s list. We identified a total 

of 11 adverse events in our sample that are on CMS’s list of hospitalacquired conditions; 1 beneficiary experienced 2 of these events, 

resulting in a total of 10 Medicare beneficiary hospitalizations with an 

adverse event. Six of the eleven adverse events were catheterassociated urinary tract infections and two were associated with 

vascular infections of a central line catheter. The remaining three 

adverse events on CMS’s list were two Stage III pressure ulcers (the 

same events counted on NQF’s list of Serious Reportable Events) and 

one case of poor glycemic control resulting in a hypoglycemic coma. 

One of the eleven adverse events on CMS’s list of hospital-acquired 

conditions resulted in higher Medicare reimbursement to the hospital. 

The adverse event on the CMS list that resulted in higher 

reimbursement is the same adverse event on the NQF list of Serious 

Reportable Events that resulted in a higher Medicare reimbursement. 

For the remaining 10 hospitalizations with adverse events on CMS’s 

list, the hospital-acquired conditions did not lead to higher Medicare 

reimbursement because the beneficiaries’ other conditions elevated 

their MS-DRG assignment to a class that included major complications 

or comorbidities. 

21 CMS implemented a new ICD-9 code for Stage III pressure ulcers, effective October 1, 

2008. Because there was no diagnosis code specifying the condition at the time of this 

hospital stay, we calculated the cost difference using an analogous code (70703). 

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FINDINGS 

Hospitals did not always include diagnosis codes reflecting 

hospital-acquired conditions in claims for Medicare reimbursement. 

Of the 11 hospital-acquired conditions we identified in our sample from 

CMS’s list, 7 conditions were not included in the billing data provided 

by hospitals.22 Six of these seven cases involved catheter-associated 

urinary tract infections and the seventh involved poor glycemic control. 

The exclusion of the diagnosis code for urinary tract infections could 

result in Medicare paying for associated care without recognizing that a 

hospital-acquired infection occurred. When a catheter-associated 

urinary tract infection is acquired in the hospital and included on the 

bill to Medicare, CMS excludes both the catheter-associated urinary 

tract infection code and certain associated infection codes in calculating 

the MS-DRG. However, when the hospital does not include the 

catheter-associated urinary tract infection code, the remaining 

associated infection codes may still be included in the calculation and 

could result in higher reimbursement. Of the six hospitalizations in 

which the hospitals omitted the catheter-associated urinary tract 

infection code from the billing data, two hospitalizations included these 

additional codes that could increase reimbursement. 

Thirteen percent of Medicare beneficiaries in two selected counties 

experienced adverse events classified as F-I on the NCC MERP harm scale 

Based on our medical review, 43 Medicare beneficiaries in two selected 

counties (13.2 percent) experienced adverse events classified in the four 

most serious harm categories on the NCC MERP index. For a number 

of patients, the same type of adverse event, such as infection or 

medication-related events resulted in a different level of harm 

depending upon such factors as intervention and the condition of the 

patient. Table 4 on the next page lists the adverse events by level of 

harm, using the NCC MERP scale of patient harm. 

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

Patient Harm (n = 43)

Category Description Adverse Events 

F Temporary harm, requiring a prolonged hospital stay 28 

G Permanent harm 4 

H Life-sustaining intervention required 8 

I Contributing to death 3 

Source: OIG analysis of 278 Medicare beneficiary hospitalizations in two selected counties, 2008. 

22 We requested billing data directly from the hospitals within a week of discharge. 

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FINDINGS 

Differences in the criteria used by 

various entities to define adverse 

events can present a challenge in 

determining an adverse event 

incidence rate. The following two examples of adverse events identified 

in our review illustrate these differences. These examples underscore 

the differences in the definitions used in the three sets of criteria that 

make up our overall rate of adverse events: NQF Serious Reportable 

Events, CMS hospital-acquired conditions, and events classified as 

F-I on the NCC MERP patient harm scale. 

Identified adverse events illustrate 

differences in the lists and criteria that 

define adverse events 

NQF’s list of Serious Reportable Events and CMS’s list of hospital-acquired 

conditions often address the same adverse event but define the event 

differently. As an example, both lists cite poor glycemic control as a 

category of adverse event. In our sample of hospitalizations, we 

identified two adverse events that were manifestations of poor glycemic 

control and resulted in serious patient harm; one event is represented 

on NQF’s list and one on CMS’s list. Both adverse events represented 

serious harm, but they do not count on both lists because of differences 

in the definition of adverse events by NQF and CMS. Generally 

speaking, manifestations of poor glycemic control are defined on NQF’s 

list by the severity of harm and on CMS’s list by the specific type of 

condition. 

NQF’s list includes as a reportable event patient death or serious 

disability associated with hypoglycemia, the onset of which occurs 

during care at the health care facility. In the case that met this 

definition, the patient experienced severe hypoglycemia to the point of 

being near respiratory arrest and resulting in a stroke with permanent 

partial paralysis on one side of the body. Our physician reviewers 

classified this event as “G-level” harm on the NCC MERP scale, but it 

did not meet CMS’s definition of a hospital-acquired condition because 

the severe hypoglycemia did not lead to a coma (the specific condition 

related to hypoglycemia within CMS’s category for poor glycemic 

control). 

The second sample case met CMS’s definition because the patient’s 

severe hypoglycemia resulted in a hypoglycemic coma. In this case, a 

patient with hypoglycemia became nonresponsive and fell into a coma. 

The coma required life-sustaining intervention to correct, therefore 

registering as “H-level” harm on the NCC MERP scale. However, 

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FINDINGS 

because the patient did not die or become seriously disabled, the case 

did not meet NQF’s criteria for a serious reportable event. 

Five beneficiaries had adverse events that resulted in permanent disability 

or death that were not on the National Quality Forum list of Serious 

Reportable Events. The NCC MERP patient harm scale classifies 

adverse events by level of patient harm rather than by the type of 

adverse event, with categories for permanent harm and death. NQF’s 

list focuses largely on serious patient disability or patient death, but the 

disability or death is reportable only if it is the result of specific events. 

In addition to the two patients previously noted who experienced events 

on NQF’s list, two other beneficiaries experienced adverse events that 

resulted in death and three more experienced adverse events that 

resulted in permanent disability. In one of these cases, the patient 

experienced a series of adverse events following a decision to delay 

surgery and died of sepsis after 51 days in the hospital. In another case, 

the patient died as the result of a heart attack following surgery. The 

remaining three patients all experienced surgical or postsurgical 

complications that resulted in permanent disability. For each of the five 

adverse events (all of which are included in our overall rate), the 

patients incurred serious harm but the contributing adverse event was 

not on NQF’s list or CMS’s list. 

In addition to the adverse events 

previously discussed, another 

43 Medicare beneficiaries 

(15.2 percent) experienced events 

classified on the NCC MERP scale as E-level harm, defined as 

temporary harm requiring medical intervention (52 events). Also, 16 of 

the 41 beneficiaries who experienced a more serious adverse event in 

our overall rate also experienced a temporary harm event (17 events). 

In consultation with physician reviewers, we determined that these 

temporary events were not comparable to the more serious adverse 

events included in our overall adverse event rate. 

An additional 15 percent of Medicare beneficiaries in 

two selected counties experienced events during their 

hospital stays that resulted in temporary harm 

The 69 events classified as temporary harm represent a wide array of 

events, from swelling at a treatment site to low-level infections (see 

Table 5). In some cases, the events resulted from standard medical 

treatment that caused an undesirable outcome in the patient, such as 

an allergic reaction to medication. These events are of interest to 

hospitals and others seeking to improve patient safety because they are 

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FINDINGS 

potential indicators of patient care problems and/or systems 

improvement opportunities. Although many cases of temporary harm 

represent fairly minor occurrences, others were classified as E-level 

harm because the patients were in the hospital for lengthy periods as a 

result of other, more serious, diagnoses, allowing hospitals to address 

the temporary harm prior to discharge. For a list of all temporary harm 

events with more complete descriptions, see Appendix G. 

Table 5: Additional Temporary Harm Events Identified Among 

Hospitalized Medicare Beneficiaries in Two Selected Counties by Type 

(n = 69) 

Types of Adverse Events 

Adverse Events and 

Percentage of Events 

Events Related to Medication 29 (42%) 

Medication-related change in mental state 10 

Medication-related skin problems 8 

Other medication-related problems 7 

Medication-related hypotension 4 

Events Related to Skin Care 13 (20%) 

Stage I or II pressure ulcer 10 

Skin tear, abrasion, or other breakdown 3 

Events Related to Surgery and Other Procedures 13 (19%) 

Postoperative hypotension 4 

Abnormal bleeding following surgery or procedure 3 

Respiratory complications related to surgery or procedure 2 

Complications related to insertion of endotracheal tube 1 

Swelling developed at site of central line insertion 1 

Postoperative urinary retention 1 

Occlusion of blood supply during procedure 1 

Events Related to Glycemic Control 4 (7%) 

Episodes of hypoglycemia 3 

Acute nonresponsive episode (not a coma) 1 

Events Related to Intravenous Fluids 5 (7%) 

Intravenous volume overload 3 

Intravenous infiltrate 2 

Hospital-Acquired Infections 2 (3%) 

Gastrointestinal infection 2 

Other 3 (4%) 

Nonmedication allergic reaction 2 

Fall leading to skin abrasions 1 

Source: OIG analysis of 278 Medicare beneficiary hospitalizations in two selected counties, 2008. 

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FINDINGS 

In a number of cases, physician reviewers indicated that these 

temporary harm events could have developed into more serious adverse 

events with a greater degree of harm without timely intervention. For 

example, we identified 11 Stage I or Stage II pressure ulcers in our 

sample. These early stage ulcers can escalate quickly to Stage III or 

Stage IV without additional medical attention.23 As another example, 

one sample Medicare beneficiary experienced a temporary blood vessel 

blockage in a leg following surgery. Clinical staff identified the problem 

after discovering that the leg was cool to the touch and restored the 

blood supply. Our physician reviewers indicated that, had the problem 

not been addressed, the lack of blood supply would likely have led to 

gangrene and amputation. Also, if episodes of severe hypoglycemia are 

closely monitored and addressed quickly, subsequent strokes and other 

serious complications may be avoided. Finally, our review found three 

events of E-level Clostridium difficile (C-diff), a highly contagious and 

potentially dangerous condition of interest to health officials. (C-diff 

was included on CMS’s list of proposed hospital-acquired conditions in 

April 2008.) We included only one of the three cases of C-diff in our 

adverse event rate. In the other two cases of C-diff, clinical staff 

identified the problem in earlier stages and treated the patient without 

increased hospitalization. 

The most common temporary harm events we identified were related to 

medication. The harm associated with these events was most often 

changes in the patient’s mental status (such as confusion); hypotension; 

and skin reactions, such as rashes and hives. The most common 

interventions to address these problems were to stop giving or to change 

the medication. 

18 

23 J.L. Zeller, C. Lynm, R.M. Glass, “Pressure Ulcers,” Journal of the American Medical 

Association, 296(8), August 23/30, 2006, p. 1020. Available online at http://jama.amaassn.org/cgi/reprint/296/8/1020.pdf. Accessed on November 18, 2008. 

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Δ CONCLUSION 

The Act requires that OIG report to Congress regarding harm caused in 

health care settings. This study is one of a series of OIG studies designed 

to meet the requirements of the Act and provides an estimated adverse 

events incidence rate among hospitalized Medicare beneficiaries in two 

selected counties. 

We found that 15 percent of Medicare beneficiaries in our sample 

experienced an adverse event during their hospital stays, few of which 

were NQF Serious Reportable Events or CMS hospital-acquired 

conditions. Further, of the 11 adverse events on CMS’s list of 

hospital-acquired conditions and the 3 adverse events on NQF’s list of 

Serious Reportable Events, only 1 resulted in higher Medicare 

reimbursement to the hospital. We also found that another 15 percent of 

Medicare beneficiaries experienced events that caused temporary harm 

that, while not comparable to the more serious adverse events included in 

our overall rate, may reflect patient care problems and learning 

opportunities. 

Although these results are not nationally representative, the extent of 

adverse events and temporary harm found in this case study 

substantiates concerns about the incidence of adverse events in hospitals 

and the importance of safety initiatives to reduce occurrences. Our 

analysis also calls attention to the difficulty of determining what events 

should be considered in an adverse event incidence rate and how those 

events should be identified and defined. Focusing our review on a limited 

geographic area (two counties) allowed OIG to learn about various 

methods for identifying adverse events in hospitals. OIG is continuing 

this work through 2009 and is currently expanding our study of incidence 

to provide a national estimate of adverse events among hospitalized 

Medicare beneficiaries. 

The Act also directs OIG to make recommendations for such legislation 

and administrative action as OIG determines is appropriate. The Act 

specifically authorized funding to continue through calendar year 2009 

and OIG will devote this funding to additional studies involving adverse 

events. Future reports in this series will include recommendations as 

appropriate. 

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CONCLUSION 

AGENCY COMMENTS AND OFFICE OF INSPECTOR GENERAL 

RESPONSE 

We received comments on a draft of this report from AHRQ and from 

CMS. 

AHRQ commented that the report was methodologically sound and 

well-written and indicated that it had no recommendations for any 

modifications to the report. 

CMS commended OIG on succinctly capturing the numerous issues 

surrounding this complex topic, acknowledged technical assistance that 

it provided to OIG in conducting this study, and indicated that it 

welcomed continued work with OIG on this issue. 

CMS reiterated its policies to encourage the prevention of adverse 

events, including quality measurement and reporting, financial 

incentives, and program oversight. Regarding financial incentives, 

CMS outlined the provision to deny payment for care associated with 

hospital-acquired conditions, indicating that OIG identification of 

hospital-acquired conditions and their effect on Medicare payment 

allowed CMS to gain a deeper understanding of the payment policy in 

practice. 

CMS also offered a point of clarification regarding the discussion of one 

of the hospital-acquired conditions, catheter-associated urinary tract 

infection. We found that in two of six cases of catheter-associated 

urinary tract infections, hospitals omitted the code that identifies the 

hospital-acquired condition but submitted other associated infection 

codes that could result in higher reimbursement. CMS indicated that it 

is not clear whether the hospitals deliberately omitted the hospitalacquired condition code, which could allow the hospitals to avoid the 

payment penalty imposed by the hospital-acquired condition payment 

provision. CMS recommended further evaluation of this issue in OIG’s 

subsequent study to estimate the national incidence of adverse events. 

OIG agrees that further evaluation is warranted and will address this 

issue in future work in this series. 

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

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Δ APPENDIX ~ A 

Tax Relief and Health Care Act of 200624

P.L. No. 109-432 

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 

24 The Tax Relief and Health Care Act of 2006, P.L. No. 109-432 § 203. 

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APPENDIX ~ A 

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

determines appropriate, including— 

(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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ΔAPPENDIX B APPENDIX ~ B 

Glossary of Selected Terms 

General Terms25

Adverse event—Harm caused by medical care. Identifying adverse 

events does not imply an error, negligence, or poor quality of care. It 

does indicate that the care resulted in an undesirable clinical outcome 

and that the clinical outcome is not related to an underlying disease. 

Cascade—An adverse event wherein one event led causally to another. 

Hospital-acquired condition—A medical condition not present prior to 

admission to a hospital. 

Medical error—The failure of a planned action to be completed as 

intended or the use of a wrong plan to achieve an aim. 

Near miss—An event or a situation that did not produce patient harm, 

but only because of intervening factors, such as patient health or timely 

intervention. 

Never event—An event or situation that should never occur in a health 

care setting. The National Quality Forum initially used the term “never 

events” to describe its list of serious adverse events, but began in 2005 

to refer to the list as “Serious Reportable Events.” 

Patient safety—Freedom from accidental or preventable injuries caused 

by medical care. 

Temporary harm event—Event classified as the lowest level of patient 

harm on the National Coordinating Council for Medication Errors 

Reporting Prevention Index for Categorizing Errors. This level of harm 

is identified as an adverse event that may have contributed to or 

resulted in temporary harm to the patient and required intervention. 

25 Sources: Definitions derived from a variety of sources including 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, Institute of Medicine, 

Washington, DC, National Academy Press, 1999; R.M. Wachter, “Understanding Patient 

Safety,” McGraw–Hill, 2008; and the glossary of the Agency for Healthcare Research and 

Quality Patient Safety Network. Available online at

http://www.psnet.ahrq.gov/glossary.aspx. Accessed on October 10, 2008. 

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APPENDIX ~ B 

Clinical Terms26

Acidosis—An abnormal condition of reduced alkalinity of the blood and 

tissues that is marked by sickly sweet breath, headache, nausea and 

vomiting, and visual disturbances and is usually a result of excessive 

acid production. 

Blood clot—A coagulated mass produced by clotting of blood.

Coronary artery bypass graft (CABG)—Heart bypass surgery performed 

to route blood flow around clogged arteries supplying the heart. 

Central line infection—An infection of the intravenous (IV) line that is 

inserted into a large vein (as the superior vena cava) typically in the 

neck or near the heart for therapeutic or diagnostic purposes (as to 

administer medicines or fluids or withdraw blood). 

Deep vein thrombosis (DVT)—A condition marked by the formation of a 

thrombus within a deep vein (as of the leg or pelvis) that may be 

asymptomatic or be accompanied by symptoms (as swelling and pain) 

and that is potentially life threatening if dislodgment of the thrombus 

results in pulmonary embolism. 

Hemiparesis—Muscular weakness or partial paralysis restricted to one 

side of the body.

Hypertension—Abnormally high arterial blood pressure that is chiefly of 

unknown cause but may be attributable to a preexisting condition (as a 

renal or endocrine disorder), that typically results in a thickening and 

inelasticity of arterial walls and hypertrophy of the left heart ventricle, 

and that is a risk factor for various pathological conditions or events 

(such as heart attack, heart failure, stroke, end-stage renal disease, or 

retinal hemorrhage). 

Hypotension—Abnormally low pressure of the blood; also called low 

blood pressure. 

Hypoglycemia—Abnormal decrease of sugar in the blood. 

Ileus—An obstruction of the bowel; specifically, a condition that is 

commonly marked by a painful distended abdomen, vomiting of dark or 

26 National Institutes of Health, U.S. National Library of Medicine, “Medline Plus 

Medical Dictionary,” updated February 4, 2003. Available online at 

http://www.nlm.nih.gov/medlineplus/mplusdictionary.html. Accessed on 

November 10, 2008. 

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APPENDIX ~ B 

fecal matter, toxemia, and dehydration and that results when the 

intestinal contents back up because peristalsis fails although the lumen 

is not occluded. 

Pressure ulcer—An ulceration of tissue deprived of adequate blood 

supply by prolonged pressure; called also decubitus, decubitus ulcer, 

and pressure sore. 

Pulmonary edema—Abnormal accumulation of fluid in the lungs. 

Sepsis—A systemic response typically to a serious, usually localized 

infection (as of the abdomen or lungs) especially of bacterial origin that 

is usually marked by abnormal body temperature and white blood cell 

count, tachycardia, and tachypnea; specifically, systemic inflammatory 

response syndrome induced by a documented infection. 

Urinary tract infection (UTI)—An infection of the tract through which 

urine passes and which consists of the renal tubules and renal pelvis of 

the kidney, the ureters, the bladder, and the urethra. 

Ventilator associated pneumonia (VAP)—A disease of the lungs that is 

characterized especially by inflammation and consolidation of lung 

tissue followed by resolution; is accompanied by fever, chills, cough, and 

difficulty in breathing; and is caused chiefly by infection that enters the 

lungs through a ventilator. 

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Δ APPENDIX ~ C 

National Quality Forum Serious Reportable Events27

The National Quality Forum (NQF) list is separated into six categories: “Serious 

disability” is defined as loss of a body part, disability, or loss of bodily function 

lasting more than 7 days or still present at time of discharge. 

Table C1: The National Quality Forum 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 the 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 being 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 fall while 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 

27 NQF, “Serious Reportable Events in Healthcare 2006 Update: A Consensus Report,” 

National Quality Forum, Washington, DC, 2007, p. 7. Available online at 

http://www.qualityforum.org/pdf/reports/sre/txsrepublic.pdf. Accessed on October 10, 2008. 

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Centers for Medicare & Medicaid Services Categories of 

Hospital-Acquired Conditions 

The Centers for Medicare & Medicaid Services (CMS) list of 

hospital-acquired conditions is divided into 10 categories. Effective 

October 1, 2008, CMS no longer pays a higher reimbursement for 

hospitalizations complicated by these categories of conditions. 

Table D1: The Centers for Medicare & Medicaid Services List of 

Hospital-Acquired 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 

A. Total knee replacement 

B. Hip replacement 

10. Surgical site infection 

A. Mediastinitis after coronary artery bypass graft (CABG) 

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. Laprascopic 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). 

Δ APPENDIX ~ D 

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Δ APPENDIX ~ E 

Detailed Methodology 

Geographic Area Selection 

For this case study, we selected hospitals in two counties. We chose the 

narrow geographic scope to minimize logistical difficulties. In 

determining the geographic areas for our case study, we considered a 

number of factors. We chose one county from each of two States to 

provide greater diversity in our population of hospitalizations. We 

selected counties that (1) had a sufficient number of hospitals so that no 

single hospital would bear a significant burden in meeting our data 

collection requests; and (2) had similar demographics, such as 

population, percentage of residents aged 65 and older, per capita 

income, and number of hospitals. The selected counties each have 12 

acute care hospitals, all of which were included in our review. The 24 

hospitals provided diversity in key characteristics, such as a range of 

bed sizes from 78 to 780; an ownership mix including nonprofit, public, 

and private; and both large networks and single-ownership facilities. 

Sample Selection 

From each of the 24 hospitals in the two-county area,28 we obtained lists 

of all Medicare-enrolled beneficiaries who were discharged during the 

week of August 10–16, 2008. From a combined list of 2,549 discharges, 

we randomly selected a total of 310 (300 from one stratum and 10 from 

another stratum). Unless otherwise noted, results in this report are 

projected to all eligible discharges from the 24 hospitals in the two 

counties during this timeframe. Hospitalizations for individual patients 

were eligible for selection if they met the following criteria: 

• the patient was enrolled in Medicare; 

• the patient was an inpatient for at least 24 hours; 

• the patient was treated as an acute care inpatient (excluding 

inpatients in psychiatric services, rehabilitation-only services, or 

long term care); and 

• the patient was discharged during our target week: 

August 10–16, 2008. 

We initially selected 300 Medicare hospitalizations using a simple 

random sampling technique. However, one hospital initially provided 

28 

28 Because the Tax Relief and Healthcare Act of 2006 stipulates that OIG shall not 

release facility-specific information, we do not name the counties in this report. 

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APPENDIX ~ E 

us with an incomplete list of discharges that affected our sampling 

frame. We then obtained a complete list from this hospital, which 

resulted in an additional stratum of 46 discharges, from which we 

randomly selected 10. 

From among the 300 hospitalizations initially selected, we excluded a 

total of 32 that were ineligible for review because they did not meet the 

criteria listed above. Following this, 278 hospitalizations remained in 

the sample for review. Among the 278 Medicare beneficiaries in the 

sample hospitalizations, the average age was 77 years with a range of 

24 to 102 years, and the average length of hospitalization was 6 days 

with a range of 1 to 53 days. A summary of the sampling design is 

provided in Table E1. 

Table E1: Sample Selection 

Stratum 1 Stratum 2 Total 

Sampling Frame 2,503 46 2,549 

Original Sample 300 10 310 

Ineligible 32 0 32 

Final Sample 268 10 278 

Source: Office of Inspector General analysis of 278 Medicare beneficiary hospitalizations in two selected 

counties, 2008.

Screening for Potential Adverse Events 

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

stage included five distinct screening processes designed to identify 

hospitalizations that appeared likely to include an adverse event. The 

screening processes included: 

• beneficiary interviews, 

• administrative data screening using the Agency for Healthcare 

Research and Quality (AHRQ) Patient Safety Indicator (PSI) 

program, 

• analysis of present on admission (POA) indicators included in 

administrative billing data, 

• reviews of hospital incident reports related to the hospitalization, 

and 

• targeted medical record screening using the Institute for Healthcare 

Improvement (IHI) Global Trigger Tool (GTT) protocol. 

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APPENDIX ~ E 

The use of multiple screening processes allowed us to test the feasibility 

and effectiveness of various methods that we are considering for use in 

future work. The screening processes also allowed us to reduce the 

number of hospitalizations requiring a full physician medical review. 

Beneficiary Interviews. For each selected hospitalization, we attempted 

to conduct structured telephone interviews with the patient or a 

designated representative to learn about the medical care experienced 

during the hospital stay. The interview protocol was designed to 

determine whether patients experienced any episodes that might be 

considered an adverse event while in the hospital and included 

questions about medication, procedures, infections, and other events on 

the National Quality Forum (NQF) and the Centers for Medicare 

& Medicaid Services (CMS) lists. We completed interviews for patients 

associated with 79 percent of sampled hospitalizations (220 of 278) and 

identified 42 hospitalizations for the second stage of review. 

Analysis of Patient Safety Indicators. Using administrative billing data 

requested directly from the hospitals, we applied AHRQ’s PSI program 

to our sample hospitalizations. The PSI program includes algorithms 

that calculate 27 quality-of-care indicators, 20 of which are 

provider-level indicators that specify that an adverse event may have 

occurred. We identified a total of 13 PSIs related to 11 patients and 

flagged these hospitalizations for the second stage of review. 

Analysis of Present on Admission Indicators. Using the same 

administrative billing data, we used POA indicators to identify claims 

that included diagnoses that were coded as not part of the patient’s 

condition upon admission. A relatively new requirement for Medicare 

Part A claims, POA indicator codes require hospitals to make a 

deliberate clinical distinction about whether diagnoses are present at 

the time of admission. POA indicators identified 112 hospitalizations 

that had at least one diagnosis not present at the time of admission. We 

included these 112 hospitalizations in the second stage of review. 

Review of In-Hospital Incident Reports. We requested that hospitals 

provide any internal incident reports associated with our sample 

hospitalizations. We received 47 incident reports relating to 36 sample 

hospitalizations from this request. These 36 hospitalizations were 

flagged for the second stage of review. 

Targeted Medical Record Screening. Contracted registered nurses 

conducted a preliminary review of medical records onsite at each 

hospital to identify potential adverse events. They followed IHI’s GTT 

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APPENDIX ~ E 

protocol, which allows reviewers to identify “triggers” in the medical 

record that may be indicative of adverse events and then explore the 

record further to determine whether an event occurred and its resulting 

level of harm. This protocol relies on a systematic method of reviewing 

medical records that takes less than 20 minutes per chart. Targeted 

medical reviews were completed for all sampled hospitalizations and 

identified 122 hospitalizations for inclusion in the second stage of 

review.

Flagged Hospitalizations. Based on the combined results of these 

screening processes, we identified 183 hospitalizations for the second 

stage of reviews: a review of the full medical record by a physician. The 

five screening processes flagged many of the same hospitalizations. 

Medical Record Review of Flagged Hospitalizations 

Three contracted physicians conducted an onsite medical record review 

of the 183 hospitalizations flagged for potential adverse events. The 

medical review protocol included a review of the results of the screening 

processes that flagged the case for review (medical record screening, 

beneficiary interview, hospital incident report, and/or administrative 

data), and then a review of the full medical record. Physician reviewers 

completed a structured medical review protocol that required them to 

describe the adverse event, the documentation that led to their 

identification of the event, and the level of harm to the patient using the 

National Coordination Council for Medication Errors Reporting and 

Prevention (NCC MERP) Index for Categorizing Medication Errors. 

Adverse Event Criteria 

To determine a meaningful overall rate of adverse events among 

hospitalized Medicare beneficiaries, this study incorporates criteria 

developed by NQF, CMS, and NCC MERP. We included in our analysis 

all patient harm incurred during the hospitalization, regardless of 

whether it was considered preventable. We did not include patient 

harm that occurred prior to entering the hospital. 

Data Analysis 

Physician Review of Findings. Following the onsite medical record 

review, we verified the adverse event findings with all physician 

reviewers to ensure that cases were determined consistently and to 

ensure consensus about complex cases. This process resulted in some 

changes to our initial adverse event findings. Most changes were 

exclusions because the identified event did not meet our study 

definition, most frequently because the adverse event was related to a 

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APPENDIX ~ E 

prior admission. We made additional changes because the physicians 

determined that the harm was part of the normal progression of the 

disease or a series of events was redefined into a single “cascade” event. 

Physician reviewers reached consensus for all hospitalizations. 

Statistical Analysis. Using information from the physician medical 

record review, we calculated adverse events incidence rates as the 

proportion of Medicare beneficiaries with at least one qualifying adverse 

event. We calculated an overall adverse event incidence rate to include 

events meeting any of the following criteria: 

1. NQF’s list of Serious Reportable Events, as the Act mandates; 

2. CMS’s list of hospital-acquired conditions; and 

3. the level of patient harm determined by physicians to have 

resulted in a prolonged hospital stay, permanent harm, 

life-sustaining intervention, or death (classified as F–I on the NCC 

MERP scale).

This overall adverse event incidence rate does not include events that 

physician reviewers identified as temporary harm events (classified as 

E-level of harm on the NCC MERP scale). 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 these temporary 

harm events, as well as separate rates for the NQF list, the CMS list, 

and the events classified as F-I on the NCC MERP scale. 

These rates were projected to all hospitalizations meeting our selection 

criteria in the two counties. Projections were calculated in SUDAAN 

using a logit transformation with a 95-percent confidence interval. 

Analysis of Medicare Payments. Following physician review and 

consensus, we analyzed administrative billing data for adverse events 

that were included on NQF’s or CMS’s lists. We calculated the 

anticipated Medicare payment amount and the amount that Medicare 

would have reimbursed for the hospitalization if the adverse event had 

not occurred. Medicare payment amounts were calculated using CMS’s 

MS-DRG Assignment with Medicare Code Editor V25 and Inpatient 

Prospective Payment System pricing software. These amounts were 

compared to determine any cost difference. We did not calculate the 

effect on Medicare payment for adverse events we identified that were 

not on the CMS or NQF lists. 

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Estimates and Confidence Intervals 

Table F1 provides estimates and 95-percent confidence intervals for key 

statistics based on analysis of 278 sample hospitalizations. Some of the 

statistics in Table F1 represent results for subgroups within our sample 

that we do not reference in the text of the report. 

Table F1: Estimates and Confidence Intervals for Key Statistics 

95-Percent Confidence Interval 

Estimate Lower Bound Upper Bound 

Percentage of Eligible Hospitalizations (n = 278) 

Overall Rate of Adverse Events 15.00% 11.43% 19.44% 

NQF Rate 0.73% 0.20% 2.67% 

CMS Rate 3.66% 2.05% 6.45% 

F through I Rate 13.17% 9.82% 17.43% 

Additional E-Level Harm Not in Overall Rate 15.22% 11.65% 19.65% 

All E Rate 17.05% 13.27% 21.64% 

Multiple Event Rate 8.78% 6.07% 12.50% 

Percentage of Hospitalizations With an Adverse Event (n = 42) 

NQF Rate 4.88% 1.32% 16.41% 

CMS Rate 24.39% 14.13% 38.74% 

F through I Rate 87.81% 74.85% 94.57% 

Highest Harm Level is E 12.20% 5.43% 25.15% 

Highest Harm Level is F 54.76% 40.54% 68.24% 

Highest Harm Level is G 7.32% 2.54% 19.33% 

Highest Harm Level is H 19.51% 10.46% 33.46% 

Highest Harm Level is I 7.32% 2.54% 19.33% 

Multiple Event Rate 43.90% 30.41% 58.36% 

Percentage of Adverse Events (n = 52) 

NQF Rate 5.88% 1.54% 19.67% 

CMS Rate 21.57% 13.16% 33.29% 

F through I Rate 84.31% 73.39% 91.29% 

Harm Level is E 15.67% 8.71% 26.62% 

Harm Level is F 54.90% 42.13% 67.06% 

Harm Level is G 7.84% 3.33% 17.37% 

Harm Level is H 15.69% 8.31% 27.63% 

Harm Level is I 5.88% 2.24% 14.56% 

Cascade Rate 13.73% 7.71% 23.24% 

Source: Office of Inspector General analysis and medical review of 278 Medicare beneficiaries hospitalized in two selected counties, 

2008. 

Δ APPENDIX ~ F 

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APPENDIX ~ A 

Tables of All Adverse Events and Temporary Harm Events 

Identified in Sample

Table G1 lists information about all adverse events that made up our 

overall rate of 15 percent of hospitalized Medicare beneficiaries (51 

adverse events). Table G2 lists information about all additional 

temporary harm events we identified (69 events). 

Table G1: Adverse Events Identified Among Medicare Beneficiaries Hospitalized in Two Selected Counties 

by Type, Harm Level, and Whether the Events are National Quality Forum (NQF) Serious Reportable Events 

or Centers for Medicare & Medicaid Services (CMS) Hospital-Acquired Conditions (n = 51) 

Adverse Event 

Harm 

Level NQF List CMS List 

Events Related to Surgery or Other Procedures (22) 

Excessive bleeding following surgery or procedure (4) 

1. Right groin hematoma at puncture site following stent placement F 

2. Wound site infection and hematoma following left knee arthroplasty F 

3. Trauma and several days of bleeding caused by insertion of Foley catheter F 

4. Cascade event in which a hematoma and a pseudoanurysm of the right femoral artery developed 

following interventional catheterization and stent placement F 

Respiratory complications related to surgery or procedure (4) 

1. Acute respiratory failure following cardiac surgery F 

2. Partial lung tissue collapse after surgical lung tissue excision G 

3. Acute respiratory failure following percutaneous endoscopic gastric feeding tube placement H 

4. Respiratory stridor following procedure H 

Postoperative ileus (4) 

1. Significant ileus following partial colon resection F 

2. Significant ileus following partial colon resection F 

3. Significant ileus following partial colon resection F 

4. Significant ileus following partial colon resection F 

Cardiac complications related to surgery or procedure (3)

1. Cascade event in which right coronary artery dissection and right ventricle laceration occurred 

during coronary angioplasty surgery H 

2. Rapid atrial flutter H 

3. Cascade event following aortic valve replacement characterized by myocardial infarction, 

respiratory failure, oliguric renal failure and cardiac arrest I 

Hypotension/blood loss related to surgery or procedure (3)

1. Hypotensive episode during hemodialysis treatment F 

2. Postoperative hemodynamic instability H 

3. Hypotensive episode during hemodialysis treatment H 

Blood clots and other occlusions (2)

1. Deep vein thrombosis of the subclavian vein following the insertion of an intravascular device F 

2. Cascade event which included two declotting procedures for the arteriovenous fistula and a 

subsequent revision of the fistula G 

Post colostomy bowel obstruction (1)

Cascade event in which a small bowel obstruction along with hypotension and gastrointestinal bleeding 

resulted following a partial colon resection G 

Premature extubation causing respiratory distress (1)

Respiratory failure following premature extubation necessitating reintubation H 

Δ APPENDIX ~ G 

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APPENDIX ~ G 

Table G1: Adverse Events Identified Among Medicare Beneficiaries Hospitalized in Two Selected Counties

by Type, Harm Level, and Whether the Events are National Quality Forum (NQF) Serious Reportable Events 

or Centers for Medicare & Medicaid Services (CMS) Hospital-Acquired Conditions (n =51) (continued) 

Adverse Event 

Harm 

Level 

NQF 

List 

CMS 

List 

Hospital-Acquired Infections (18) 

Urinary tract infection (6)

1. Urinary tract infection (resistant pseudomonas) associated with a Foley catheter E X 

2. Urinary tract infection (Proteus mirabilis) associated with a Foley catheter E X 

3. Urinary tract infection (Klebsiella oxytoca) associated with Foley catheter E X 

4. Urinary tract infection (Candida) associated with Foley catheter E X 

5. Urinary tract infection (Morganella morganii) associated with Foley catheter E X 

6. Urinary tract infection (enterococcus) associated with a Foley catheter E X 

Surgical infection (3) 

1. Surgical site infection following procedure F 

2. Prolonged fever following surgical procedure F 

3. Cascade event in which postoperative persistent enterococcal bacteremia led to multiple complications 

including significant cardiovascular instability and respiratory failure leading to cardiac arrest I 

Respiratory infection (not ventilator associated) (3) 

1. Postoperative lower respiratory infection F 

2. Hospital-acquired pneumonia F 

3. Hospital-acquired pneumonia F 

Central line infection (2) 

1. Central line infection (Vancomycin-resistant enterococcus) F X 

2. Central catheter line sepsis (Staphylococcus epidermidis) F X 

Ventilator-associated pneumonia (2)

1. Ventilator-associated MRSA (Methicillin-resistant Staphylococcus aureus) infection F 

2. Ventilator-associated pneumonia F 

Gastrointestinal infection (1)

Gastrointestinal infection (Clostridium difficile) following antibiotic treatment F 

Sepsis as result of delay in performing surgery (1)

Cascade event in which septic shock led to respiratory failure, a sacral pressure ulcer, wound disruption, gangrene, 

bilateral pleural effusions requiring chest tube insertion, renal failure and ultimately a venous thrombo-embolism 

(deep vein thrombosis and pulmonary embolism) 

I 

Events Related to Medication (6)

Medication-related hypotension (2)

1. Hypotensive episode while on pain medication (opioid) F 

2. Hypotensive episode secondary to cardiac medication (β-blocker) F 

Medication-related delirium (1)

Delirium associated with medication (benzodiazepines) F 

Medication-related gastrointestinal bleed (1)

Gastrointestinal bleeding from a cecal ulcer on the large ascending colon associated with anti-coagulation 

medication F 

Kidney damage associated with use of contrast (1) 

Kidney dysfunction associated with contrast media F 

Medication-related acute renal insufficiency (1) 

Acute renal failure associated with dehydration secondary to colchicine induced diarrhea F 

Events Related to Patient Care (5) 

Pressure ulcer (2) 

1. Stage III pressure ulcer E X X 

2. Stage III pressure ulcer E X X 

Stroke and resulting paralysis related to hypoglycemia (1) 

Stroke and permanent left hemiparesis associated with severe hypoglycemia G X 

Hypoglycemic coma (1) 

Temporary hypoglycemic coma secondary to insulin H X 

Intravenous volume overload (1) 

Fluid overload that led to pulmonary edema F 

Source: Office of Inspector General (OIG) analysis and medical review of 278 Medicare beneficiaries hospitalized in two selected counties, 2008.

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APPENDIX ~ G 

Table G2: Temporary Harm Events, E-level on the National Coordinating Council for Medication 

Errors Reporting and Prevention Index for Categorizing Errors (NCC MERP) Patient Harm Scale, 

Identified Among Medicare Beneficiaries in Two Selected Counties by Type (n = 69) 

Adverse Event 

Events Related to Medication (29) 

Medication-related change in mental state (10)

1. Hallucinations secondary to pain medication (opioid) 

2. Delirium and combativeness secondary to pain medication (hydromorphone) 

3. Delusions and psychosis secondary to pain medication (opioid) 

4. Confusion secondary to pain medication (narcotics) 

5. Confusion and combativeness secondary to medication (benzodiazepine) 

6. Confusion secondary to medication (hydromorphone) 

7. Confusion secondary to pain medication (opioid) 

8. Confusion secondary to pain medication (opioid) 

9. Change of mental status and slurred speech secondary to medication (butyrophenone) 

10. Change of mental status secondary to medication (digoxin) 

 Medication-related skin problems (8) 

1. Significant itching secondary to seizure medication 

2. Significant itching secondary to medication (opioid) 

3. Rash secondary to antibiotics (fluoroquinolone) 

4. Significant itching at epidural anesthesia needle insertion site 

5. Skin rash secondary to antibiotic treatment (fluoroquinolone) 

6. Hives secondary to intravenous (IV) contrast 

7. Global rash secondary to steroid treatment (corticosteroid) 

8. Itching secondary to pain medication (opioid) 

Other medication-related problems (7) 

1. Urinary retention secondary to pain medication (opioid) 

2. Leg weakness secondary to epidural anesthesia 

3. Constipation secondary to pain medication (opioid) 

4. Hematuria secondary to anticoagulation therapy (heparin) 

5. Thrush (Candida) infection secondary to antibiotics 

6. Significant white blood cell reduction secondary to antibiotics (glycopeptide) 

7. Constipation secondary to pain medication (narcotics) 

Medication-related hypotension (4) 

1. Hypotension secondary to cardiac medication (β-blocker) 

2. Hypotensive episode secondary to pain medication (opioid) 

3. Hypotension secondary to medication (antiandrogen) 

4. Hypotension and bradycardia secondary to multiple medications 

Events Related to Skin Care (13) 

Pressure ulcer (10)

1. Stage II pressure ulcer 

2. Stage II pressure ulcer 

3. Stage II pressure ulcer 

4. Stage II pressure ulcer 

5. Stage II pressure ulcer 

6. Stage II pressure ulcer 

7. Stage II pressure ulcer 

8. Stage II pressure ulcer 

9. Stage I pressure ulcer 

10. Stage I pressure ulcer 

Skin tear, abrasion or other breakdown (3)

1. Cascade event in which digoxin toxicity led to diarrhea and dehydration followed by a Stage I skin breakdown 

2. Skin tear 

3. Skin abrasion caused by goggles worn during procedure 

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APPENDIX ~ G 

Table G2: Temporary Harm Events, E-level on the National Coordinating Council for Medication 

Errors Reporting and Prevention Index for Categorizing Errors (NCC MERP) Patient Harm Scale, 

Identified Among Medicare Beneficiaries in Two Selected Counties by Type (n = 69) (continued) 

Adverse Event 

Events Related to Surgery and Other Procedures (13) 

Postoperative hypotension (4)

1. Postoperative hypotension of indeterminate etiology 

2. Transient hypotension following endovascular procedure 

3. Hypotensive episode following an endovascular procedure 

4. Postoperative hypovolemia 

Abnormal bleeding following surgery or procedure (3) 

1. Traumatic bleeding due to nastrogastric tube insertion 

2. Excessive bleeding at epidural anesthesia needle insertion site 

3. Swelling and hematoma at the surgical site 

 Respiratory complications related to surgery or procedure (2) 

1. Respiratory distress and subcutaneous emphysema (air trapped in the subcutaneous layer of the skin) 

2. Significant right plural effusion following aortic valve replacement surgery 

Complications related to endotracheal tube (1) 

Difficulty swallowing due to trauma incurred during insertion of endotracheal tube 

Swelling developed at site of central line insertion (1) 

 Lymphedema developed around site of central line insertion point

Postoperative urinary retention (1) 

 Postoperative urinary retention 

 Occlusion of blood supply during procedure (1) 

 Transient occlusion of left lower extremity blood supply during endovascular procedure 

Events Related to Glycemic Control (4) 

 Episodes of hypoglycemia (3) 

1. Several episodes of hypoglycemia secondary to insulin 

2. Several episodes of hypoglycemia secondary to insulin 

3. Transient hypoglycemia secondary to insulin during a period of fasting for surgery 

 Acute nonresponsive episode related to hypoglycemia (1) 

 Hypoglycemic event that led to period of unresponsiveness 

Events Related to Intravenous Fluids (5) 

 Intravenous volume overload (3) 

1. Postoperative fluid overload 

2. Fluid overload that led to exacerbation of chronic heart failure 

3. Fluid volume overload that led to respiratory decompensation 

Intravenous infiltrate (2) 

1. Intravenous infiltrate resulting in pain and swelling 

2. Significant local intravenous antibiotic infiltrate 

Hospital-Acquired Infections (2) 

 Gastrointestinal infection (2) 

1. Infection (Clostridium difficile) that developed following treatment for bacterial pneumonia 

2. Infection (Clostridium difficile) that developed following antimicrobial treatment for enterococcal septicemia 

 Other (3) 

 Nonmedication allergic reaction (2) 

1. Contact dermatitis 

2. Allergic reaction to adhesive tape 

 Fall (1) 

 Fall occurring during the hospital stay 

Source: OIG analysis and medical review of 278 Medicare beneficiaries hospitalized in two selected counties, 2008

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Δ APPENDIX ~H 

Agency Comments: Agency for Healthcare Research and Quality

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APPENDIX ~ H 

Agency Comments: Center for Medicare & Medicaid Services

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APPENDIX ~ H 

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Δ 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 for Evaluation and Inspections. 

Amy Ashcraft and Ruth Ann Dorrill served as team leaders for this 

study. Other principal Office of Evaluation and Inspections staff from 

the Dallas regional office who contributed to the report include Tom 

Browning, Deborah Cosimo, Anthony Guerrero-Soto, Sai Loganathan, 

Christi Macrina, Deborah McGurk, Jeremy Moore, Lyndsay Patty, and 

Susan Wolfe; other regional and central office staff who contributed 

include Rob Gibbons, Veronica Gonzalez, Scott Hutchison, Sue 

Nonemaker, Julie Taitsman, M.D., and Rita Wurm.