Validating the Collection of Separately Billed Doctor Expenditures for Hospital Services: Results

from the Medicare-MEPS Validation Study

Samuel Zuvekas and Gary Olin

Agency for Healthcare Research and Quality Working Paper No. 08004 March 2008

Suggested citation: Zuvekas S, Olin G. Validating the Collection of Separately Billed Doctor

Expenditures for Hospital Services: Results from the Medicare-MEPS Validation Study. Agency

for Healthcare Research and Quality Working Paper No. 08004, March 2008,

http://gold.ahrq.gov.

AHRQ Working Papers provide preliminary analysis of substantive, technical, and methodological

issues. The papers have not undergone external peer review. They are distributed to share

valuable experience and research. Comments are welcome and should be directed to the

authors. The views expressed are those of the authors and no official endorsement by the

Agency for Healthcare Research and Quality or the Department of Health and Human Services is

intended or should be inferred.
Validating the Collection of Separately Billed Doctor Expenditures for Hospital Services: 

Results from the Medicare-MEPS Validation Study 

Samuel H. Zuvekas and Gary L. Olin, AHRQ 

March 2008 

ABSTRACT 

The Medicare-MEPS Validation Study uses Medicare claims for a subset of beneficiaries in the 

2001-2003 MEPS Public Use Files to evaluate the quality of use and expenditure data collected 

in the MEPS. In this part of the study, we focus entirely on the quality of separately billed 

doctor (SBD) expenses associated with inpatient, emergency department, and outpatient 

department services. We first compare CMS claims data to MEPS estimates of SBD 

expenditures in aggregate for all hospital events identified by households and medical providers 

in the MEPS. The MEPS estimates of SBD expenditures are approximately 2-5 percent lower 

than the amounts reported on the Medicare Part B claims for reimbursement of physicians’ 

services associated with hospital services for the matched subset of beneficiaries. We next 

compare facility and SBD expenditures for household-reported hospital events with an exact 

match to a CMS hospital claims record. These matched pair analyses also show SBD 

expenditures lining up well between MEPS and the CMS claims, particularly for hospital stays. 

Based on the aggregate and matched pair analyses, we conclude that the current SBD data 

collection process produces accurate information on expenditures for doctors who bill separately 

from hospitals for their services. Additional analyses suggest some potential for streamlining the 

SBD data collection process for certain types of outpatient department visits that infrequently 

have SBD expenses associated with them. 

Samuel H. Zuvekas 

Agency for Healthcare Research and Quality 

Division of Social and Economic Research 

Center for Financing, Access, and Cost Trends 

540 Gaither Road 

Rockville MD 20850 

Samuel.Zuvekas@ahrq.hhs.gov 

Phone: (301)427-1673 

And 

Gary L. Olin 

Agency for Healthcare Research and Quality 

Division of Survey Operations 

Center for Financing, Access, and Cost Trends 

540 Gaither Road 

Rockville MD 20850 

Gary.Olin@ahrq.hhs.gov 

2
 
Validating the Collection of Separately Billed Doctor Expenditures for Hospital Services: 

Results from the Medicare-MEPS Validation Study 

INTRODUCTION 

Expenses billed separately by physicians and other providers for treatment provided in 

hospital settings are an important component of medical costs, accounting for 11 percent of all 

hospital treatment expenses according to the most recent data from the 2005 Medical 

Expenditure Panel Survey (MEPS) . Typical separately billed doctor (SBD) expenses include 

fees for surgeons, radiologists, and anesthesiologists. As part of the ongoing Medicare-MEPS 

Validation Study, we use Medicare claims for a subset of beneficiaries in the 2001-2003 MEPS 

Public Use Files to evaluate the validity of SBD expenditures collected in MEPS. 

We first compare Medicare claims for physician services provided in hospitals to MEPS 

estimates of SBD expenditures in aggregate for all inpatient (IP), outpatient (OP), and 

emergency room (ER) hospital events identified by households and medical providers in the 

MEPS. We next compare facility and SBD expenditures for household-reported hospital events 

with an exact match to a CMS hospital claims record. Based on the aggregate and matched pair 

analyses, we conclude that the current SBD data collection process produces accurate 

information on expenditures for doctors who bill separately from hospitals for their services. We 

also examine opportunities to improve the efficiency of SBD data collection by identifying 

hospital events where SBD expenses infrequently occur. 

3
 
 

 

2. BACKGROUND: MEDICARE-MEPS VALIDATION STUDY 

Medicare administrative data are among the few data sources that can be used to 

benchmark use and expenditures data in the MEPS. The full study includes analyses of overand under-reporting of expenditures by household respondents and medical providers; the 

accuracy of household-reporting of hospital stays, emergency room visits, and ambulatory visits 

to physicians’ offices and hospital outpatient departments; the impact of dying or being 

institutionalized during the year on MEPS estimates of expenditures; and issues related to the 

abstraction and use of medical provider component (MPC) data in the survey. This report 

focuses entirely on the quality of SBD data collected or imputed for hospital events identified by 

households and medical providers in the MEPS. 

For the Medicare-MEPS Validation Study, we acquired Medicare enrollment and claims 

data from the Centers for Medicare and Medicaid Services (CMS) for a subset of beneficiaries in 

MEPS during the years 2001-2003. The group includes all of the survey respondents who 

provided a complete Medicare health insurance claim number (HICN) and were matched exactly 

to the same HICN or to Social Security number, gender and date of birth in the Medicare 

administrative records. The number of beneficiaries in the exact match group was 1,632 in 2001, 

1,981 in 2002, and 1,761 in 2003.1

 These beneficiaries were eligible for Medicare for all or part 

of the year(s) they were in the survey, and they could have been in either Medicare fee-forservice or managed care. This non-random sample of persons providing valid numbers that 

were matched to CMS records represents 44 percent of the eligible Medicare Population in 

MEPS. 

We use the Medicare enrollment data to determine the length and type of coverage— 

Medicare fee-for-service or managed care or a mix of the two—for each year a beneficiary was 

1

 Some of these beneficiaries were in the survey for two years (2001-2002 or 2002-2003). 

4
 
in the MEPS. Then, for the always covered by Medicare fee-for-service beneficiaries in our 

sample, we compare the final action claims submitted by hospital inpatient and outpatient 

departments, skilled nursing facilities, home health agencies, hospices, and non-institutional 

providers to information reported by households and medical providers in the MEPS. 

All of our analyses are restricted to Medicare-covered events and Medicare payments 

rather than total expenditures (Medicare payments plus payments by all other sources). We are 

restricted to comparisons of Medicare-covered events because the CMS claims do not include 

information on the beneficiaries’ use of non-covered services or care by providers who do not 

bill Medicare (e.g., a VA facility). In addition, the focus on Medicare payments is necessary 

because the CMS claims are an accurate reflection of Medicare payments to a provider, but they 

do not show payments actually made by individuals or supplemental insurance toward 

beneficiary cost sharing liability. As a consequence, the claims are not always a reliable source 

of information on total expenditures for an event. Medicaid payments to hospitals and 

physicians for the cost sharing liability of a dually eligible beneficiary, for example, are routinely 

discounted. 

3. BACKGROUND: SEPARATELY BILLED DOCTOR EXPENSES (SBD) 

In this phase of the validation study, we evaluate the quality of SBD data collected in the 

MEPS MPC. These data are collected in two stages. First, hospital medical records and patient 

accounts information from the MPC are manually reviewed to identify all doctors who may have 

billed separately from the hospital for care provided during a stay or visit. Second, the potential 

SBDs are contacted by telephone and asked about separately billed services for the hospital 

event(s) in question. This two stage process is the only practical way of collecting information 

5
 
on doctors’ care not included in hospital facility charges, but it does raise two concerns. One is 

that some SBD expenditures may be missed if not all SBDs are identified in the manual review 

of hospital medical records. The other is that the data collection process may be inefficient 

because many of the potential SBDs identified in the manual reviews disavow billing separately 

for services during the hospital event(s) in question when they are contacted. 

4. METHODS 

To compare MEPS SBD expenditures to the CMS claims, we start by restricting the 

matched sample to survey respondents who were in-scope the entire calendar year, did not die 

and were not institutionalized, and had Medicare fee-for-service all year. They allow us to 

compare use and expenditures data for beneficiaries in the survey who were asked about their 

health care for the entire year and also had Medicare claims for all of their covered services 

regardless of what they reported in the survey. We refer to the full-year, fee-for-service group as 

the target population for these analyses. This target population is used in most of the analyses in 

the Medicare-MEPS Validation Study. Sample sizes for this target population are 1203, 1502, 

and 1340, respectively for the years 2001 through 2003. This target population represents 29 

percent of the full Medicare sample in MEPS for 2001-2003. Combined with the cumulative 

overall MEPS response rate of approximately 60 percent, this leads to an effective yield rate of 

18 percent of the Medicare population for these analyses. 

We make two types of SBD expenditure comparisons for the target population in this 

phase of the Medicare-MEPS validation study. First, we compare all of the SBD expenditures 

reported or imputed in the household and medical provider components of MEPS to CMS carrier 

file claims by SBDs for the same set of hospital events (IP, OP, and ER). The aggregate SBD 

6
 
 

expenditure comparison allows us to assess the overall accuracy of SBD expenditures in the 

MEPS without getting into the detail of household or medical provider misreporting of eventlevel information. Second, we compare facility and SBD expenditures for matched pairs of 

hospital events in the MEPS HC and the CMS claims files. The matched pair comparison 

provides information on the accuracy of SBD expenditures collected for individual events in 

MEPS while allowing for the possibility that facility and SBD expenditures are sometimes 

reported together in the billing records of hospitals in the MPC. 

We also examine patterns of disavowal by event type and physician specialty in the MPC 

SBD data in an effort to determine whether the SBD data can be collected more efficiently. This 

review is undertaken because a large percentage of the physicians abstracted from hospital 

medical records and patient bills are not SBDs. The question is whether or not certain physician 

specialties can be ignored when abstracting potential SBDs from the hospital data. 

4.1 CMS claims data 

CMS claims data are stored in one of seven standard analytic files based on the type of 

billing record the provider is required to use for reimbursement of Medicare covered services. 

These seven are the inpatient, outpatient, Carrier (Part B), durable medical equipment, home 

health, skilled nursing facility, and standard analytic files hospice files (see Olin et al 2008 and 

RESDAC 2006 for additional detail on the files). SBD claims are included in the Medicare 

Carrier file along with other Part B claims by non-institutional providers. There are no direct 

links between Carrier file claims and hospital facility claims in the inpatient and outpatient files, 

so an indirect method is needed to identify physicians’ charges for services provided in hospitals. 

We use the place of service variable included on each Part B claim to determine whether a 

7
 
physician’s claim was associated with a hospital facility event. This variable may not be 100 

percent reliable, but it appears to differentiate well in the vast majority of cases. An alternative 

would have been to use CPT-4 codes to separate Part B claims by place of service (office or 

hospital), but CPT-4 codes do not reliably distinguish between services provided in offices and 

hospitals. For example, the 99201-99215 series of physician evaluation and management codes 

are used by both office-based physicians and hospital outpatient departments. 

4.1.1 Aggregate expenditures 

To determine total SBD expenditures in the CMS data, we first derived aggregate 

estimates of SBD expenditures for the target population by summing across all CMS Part B 

claims during the calendar year where the place of service variable indicated a hospital facility 

(inpatient, outpatient, or emergency room). The annual totals reflect the amounts paid by 

Medicare for physicians’ services that were provided during hospital stays and hospital 

ambulatory visits but not included in the hospital facility charges. No effort was made to link 

these claims to Medicare claims in the IP and OP files for reimbursement of facility charges at 

this point in the analyses. Instead, we simply compare total SBD expenditures in the CMS data 

to the SBD expenditures reported and imputed for hospital events by the target population in the 

MEPS. However, to create comparable sets of events and services, we had to exclude CMS 

claims for hospital events not in the MEPS and for separately billed laboratory services by 

hospital outpatient departments. These adjustments to the CMS data are described below: 

CMS Adjustment #1: SBD claims for IP and ER events in CMS claims not identified in HC and 

MPC. 

8
 
We subtracted from the CMS SBD total all of the SBD expenditures associated with IP 

and ER events that were not identified by households or medical providers in MEPS. We 

identified CMS claims for IP and ER events that were not in the MEPS through a semiautomated process linking all IP and ER events in the CMS, HC and MPC data files. This 

process included a hand review of all links. 

CMS Adjustment #2: OP events in CMS claims not identified in HC and MPC. 

Similarly, we subtracted from the CMS SBD total all of the SBD expenditures associated 

with OP events that were not identified either by households or medical providers in MEPS. We 

did not link all OP events as we did with ER and IP events because of resource constraints, far 

larger number of events, and much higher proportion of date mismatches. Instead, we took the 

average ratio of total OP SBD dollars to total ER/IP SBD dollars combined after subtracting out 

SBDs associated with OP laboratory/radiological services (see adjustment #3), and multiplied the 

Adjustment #1 amounts by this ratio of 0.4. (Alternative assumptions for this ratio have a 

negligible effect on the overall MEPS to CMS SBD ratio). To the extent that ER and IP events 

are more salient events than OP events and therefore likely to have a fewer percentage of events 

in the CMS claims that do not match to either HC or MPC reported events, this represents a 

lower bound estimate. 

CMS Adjustment #3: SBDs associated with hospital OP laboratory/diagnostic services. 

A large number of the CMS OP claims only have laboratory or radiological CPT codes. 

Many of these OP “events” are not reported by households even though a physician office visit is 

often reported for the same day as the OP event. We believe that hospital outpatient departments 

9
 
 

are essentially serving as separately billing laboratories (SBLs) in these cases, and households do 

not typically report the lab and radiology services separately from the physician visit. A future 

report will discuss the implications of SBL expenditures on MEPS estimates of total expenditure 

in more detail. Here we drop the CMS OP claims for lab and radiology services to make the 

CMS and MEPS estimates of SBD expenditures for hospital events in MEPS more comparable. 

4.1.2 Matched pair expenditures 

Both facility and SBD expenditures are used in the matched pair comparisons of CMS 

claims to hospital events reported by households in MEPS. To make these comparisons, we first 

had to link each of the CMS SBD claims to a specific hospital facility claim in the CMS IP and 

OP files.2

 We did this by matching the SBD claims to hospital claims for facility charges by 

date(s) of service on the CMS claims records. We allowed leads and lags of 1 day for ER visits 

and hospital stays to allow for ambiguity over dates of service from late night admissions. 

Technically, not all of these SBD claims were actually submitted separately to Medicare by the 

physician. In the MEPS MPC data, for example, we found instances where a hospital would 

submit claims to Medicare for both the facility costs (an inpatient or outpatient institutional bill) 

and the physician services (a carrier file bill). We nonetheless call all of the CMS Part B claims 

associated with these hospital events SBDs. However, it is important to keep this hospital billing 

convention in mind when comparing CMS and MEPS “SBD” expenditures because hospital 

expenditures in the MEPS MPC have not been split between facility and physician charges when 

the hospital billing information includes both types of Medicare reimbursement. 

2

 Hospital claims for emergency room services are included in both the CMS IP and OP files. We identified and put 

the ER claims in a separate file for comparison to the MEPS ER events. 

10
 
After the SBD claims were linked to individual claims for hospital care in the CMS files, 

we matched the CMS hospital events to hospital events in the MEPS HC. The description of this 

matching process is described in the MEPS data section on subsetting CMS and MEPS records 

to be used in the matched pair expenditure comparisons. 

4.2 MEPS Data 

SBD data are collected entirely in the MPC of the survey. Most of the information on 

SBD expenditures is provided by the physicians who billed separately from the facility for care 

provided during a hospital stay or visit. The process of collecting expenditure data for these 

physicians requires a manual review of hospital medical and patient account records to identify 

potential SBDs who are later contacted for information on services they provided during the 

hospital events captured in the MPC. However, some hospitals include SBD expenditures as 

well as hospital facility expenditures in their billing records. When the hospital bills include 

reimbursements for both types of services (facility and physician), the SBD expenditures are 

usually counted as part of the facility expenditure. As a consequence, SBD expenditures in the 

MPC are collected explicitly from physicians in the survey and implicitly from hospital billing 

records containing both types of expenditures. 

Each potential SBD-hospital event pair is called an SBD node in MEPS.. For example, 

an inpatient hospital stay might have separate SBD nodes for the surgeon, anesthesiologist, and 

radiologist, with the nodes covering all encounters during that inpatient stay. Separate nodes are 

also created when a physician provides care for multiple hospital outpatient visits: one for each 

visit. SBD nodes are classified according to whether the physician provided complete data, 

incomplete data, refused, or disavowed the patient (that is, they do not know the patient or did 

11
 
not provide separately billable services to the patient for the hospital event). The SBD 

identification process is designed to be as expansive as possible to identify all potential SBD 

nodes, resulting in about half of these nodes being disavowed. For example, a physician’s name 

will appear in medical records as the referring physician or physician of record but the physician 

did not actually provided an care at the hospital. Expenditures from complete SBD nodes are 

generally used as is, while an imputation process is used to impute expenditures from incomplete 

or refusal SBD nodes. Disavowals nodes are assumed valid and SBD expenditures for that node 

are considered to be $0. Expenditures (actual and imputed) are then summed across all SBD 

nodes for each hospital event collected in the MPC. For hospital events that did not match to a 

MPC hospital record, SBD expenditures are also imputed. Additional information about MPC 

and SBD sampling and estimation procedures is available in the MEPS Methodology Report #9 

(Machlin and Taylor 2000) and in the MEPS public use file documentation for the event-level 

files (see for example (HC-077D Hospital Inpatient File, HC-077E Hospital Emergency Room 

Visits File, and HC-077F Outpatient Department Visits). 

4.2.1 Aggregate expenditures 

The comparison of aggregate SBD expenditures in the CMS data and the MEPS also 

requires making adjustments to the MEPS data. These adjustments are necessary for two 

reasons. First, some SBD expenditures are combined with other expenditures in the MEPS HC 

and MPC. Second, other SBD expenditures collected in the MPC are missing altogether from 

the MEPS public use files (PUFs) because not all of the MPC hospital events are matched to 

household-reported events. Adjustments for these problems are described below: 

12
 
MEPS Adjustment #1: SBDs embedded in office-based events. 

When hospital events collected in MPC are matched to office-based visits reported by 

households, the SBD and facility expenditures are combined and reported as a single expenditure 

on the PUFs under office-based visits. Additional SBD expenditures are embedded in officebased events during the imputation process. The process uses a weighted sequential hot-deck 

procedure which uses donors with complete expenditure information to impute expenditure data 

for visits for household-reported office-based visits with missing or incomplete expenditure data. 

Some of these donors in this hot-deck procedure were cases that matched to hospital events in 

the MPC and where the SBD and facility expenditures were combined and imputed to the officebased records with missing expenditure information. We added these SBD dollars embedded in 

office-based expenditures to the SBD dollars reported for ER, IP, and OP events in the PUFs. 

MEPS Adjustment #2: Unmatched MPC Hospital events. 

We added SBD dollars associated with hospital events collected during the MPC that 

were not matched to household events. This estimate includes only the SBD dollars from 

complete nodes, although additional dollars would be expected from SBD nodes (refusals or 

incompletes) that would have been imputed if these hospital events had been matched) 

Consequently, it is a lower bound estimate of SBD expenditures for unmatched hospital events in 

the MPC. 

MEPS Adjustment #3: SBDs captured with ER/IP/OP Facility Payments. 

Hospitals sometimes bill Medicare for Part B services provided by physicians associated 

with hospital events. These Part B physician expenditures are generally added to the facility 

13
 
payments collected in the MPC, but they are separate claims in the CMS data. Therefore, an 

adjustment is necessary to estimate SBD expenditures included in the MPC hospital 

expenditures. For ER visits, we clearly identified a minimum of 4-8% of Part B physician 

payments that were combined in this manner in MPC. For OP, and especially, IP events, it was 

more difficult to quantify these embedded payments, because of the large number of refusal 

nodes and abstraction errors. Consequently, we used a conservative estimate of 3 percent 

overall. (A larger adjustment would bring MEPS SBD expenditures even closer to the CMS 

data). 

4.3 Matched Pair Analyses 

We compare facility and SBD expenditures for matched pairs of hospital records reported 

in the CMS claims and in the MEPS HC by hospital event type (IP, ER, and OP). The 

methodology for identifying these matched pairs of events is described below: 

Inpatient stay pairs 

 For inpatient hospital stays (IP), we first selected all hospital records in the MEPS MPC 

with complete facility payment data that matched an inpatient hospital record in the CMS claims 

based on our hard links. We next subset these matched pairs of CMS-MPC inpatient records to 

those that were matched to the MEPS HC data because SBD expenditures for nodes with 

incomplete payment data or refusals are only imputed for events that match to the HC. Finally, 

we subset to matched pairs of inpatient records where any discrepancy in Medicare facility 

payments reported in the MPC compared to what is contained in the CMS claims records is less 

than 1,000 dollars. Our hand review of these cases found that almost all were the result of clear 

14
 
 

 

abstraction errors rather than possible Medicare Part B physician payments embedded in the 

facility payments. Table 1 further describes this sample selection in terms of numbers. From 

this, we calculate that 15% of the inpatient pairs had to be discarded in 2001 and 11% in 2002 

and 2003 because of large discrepancies in facility payments. 

Emergency room visit pairs. 

The selection of ER pairs is similar that used to select IP stays pairs. We first discarded 

ER visits that preceded inpatient hospital stays. We then selected all ER records in the MEPS 

MPC with complete facility payment data that matched an ER record in the CMS claims based 

on our hard links. We then subset those pairs that matched to the MEPS HC. We only discarded 

a handful of ER cases based on the $1000 discrepancy threshold. At lower thresholds it becomes 

increasingly difficult to distinguish between abstraction errors and embedded Part B payments. 

Outpatient department visit pairs. 

We matched OP pairs in a slightly different manner based on event dates rather than hard 

links that we reviewed because of the large number of OP events. We discarded all OP events 

that were associated with either an ER or IP event. We also discarded all matched pairs that 

contained a global fee for the facility payment or the physician component of the care. 

We summed Medicare payments across all Medicare Part B claims that were identified as 

being associated with each of the matched hospital events. Similarly, we summed all of the SBD 

Medicare payment amounts for each hospital event.3

 We then compared total facility 

3

 SBD nodes were linked to specific hospital events by Westat as part of the SBD data collection process using 

primarily a hand matching process. We did not overwrite these hand links although there were inevitably some 

errors in this process. 

15
 
expenditures, total SBD expenditures, and total facility plus SBD expenditures for the subset 

matched pairs without large discrepancies in facility payments. 

4.4 SBD Node Disposition Analysis 

The purpose of the SBD node disposition analysis is to determine whether the MPC SBD 

data collection process can be made more efficient by identifying categories of physicians who 

should not be contacted for information on separately billed services even though they were 

identified as potential SBDs in the manual reviews of hospital medical and billing records. This 

analysis is done using only the MEPS MPC data. In it, we compare of the results of our efforts 

to collect SBD expenditures for all potential SBDs in the MPC sorted by physician specialty and 

event type (IP, OP, or ER) for the years 2001-2003. 

5. FINDINGS 

5.1 Aggregate SBD expenditures 

Table 2 contains our estimates of total SBD expenditures in the CMS claims and MEPS 

before and after adjustments for each of the years 2001, 2002, and 2003. Looking at the last 

column, the total Medicare SBD payments in the CMS claims (or more accurately Medicare Part 

B physician claims for services provided in hospitals) before adjustments was $688,046 in 2003 

compared to the unadjusted MEPS PUF SBD total of $480,802. After adjusting for hospital 

events that were not reported by the household, SBD dollars embedded in events reported by the 

household as office-based visits, and Medicare Part B payments captured with the facility 

payments in MPC data collection, the comparable SBD totals are $628,903 in the CMS data and 

$616,462 in MEPS, or a difference of 2 percent. Differences for 2001 and 2002 are similar, 

16
 
suggesting that the MEPS process of collecting and imputing SBD expenditures works well. 

Moreover, although there is some inherent squishiness in the adjustments we made, the 

adjustments are actually lower bound estimates in many cases. 

5.2 Matched Hospital Events 

Table 3 contains the results of the matched pair analyses by event type. The reported 

facility payments in the MEPS MPC exceed those reported in the CMS claims data for all years 

and event types. The differences in reported Medicare facility payments are slight for hospital 

stays but substantial for ER and OP visits. In some cases, the excess facility payments are clearly 

the result of Medicare Part B physician services being billed by the hospital, especially for ER 

visits. In other cases, there are clear abstraction errors leading to overestimates in the MEPS 

MPC data. It proved impossible to fully separate out these two effects. Thus, the SBD payment 

line in the table contains no adjustment for Medicare Part B payments billed by hospitals in the 

MPC. This SBD payment line shows lower estimates in the MEPS for 2002 and 2003 especially 

compared to the CMS data. However, when the facility and SBD amounts are combined, the 

MEPS totals are either very close to (in the case of hospital stays) or significantly exceed the 

CMS claims amounts. For example, the combined physician and facility components of 

Medicare payments hospital stays for MEPS were within 99 percent of that reported in the CMS 

data and actually exceeded CMS claims amounts by 2 percent for ER visits and 11 percent for 

OP visits. Future analyses will explore further the reasons why expenditures were 11 percent 

higher in MEPS for OP visits. 

The aggregate and matched pair analyses both tell essentially the same story. 

Discrepancies between SBD dollar amounts reported in MEPS and CMS are principally due to 

17
 
differences in the number of hospital events reported by households, and the SBD data collection 

process does a reasonable job of collecting SBD expenditures for hospital events reported by 

households. However, the differences between CMS and MPC expenditures for matched pairs 

of OP and ER events are large enough to warrant further investigation. As part of this 

investigation, we will review MPC billing data for OP and ER events with relatively large 

expenditures compared to the CMS claims. 

5.3 SBD Node Disposition Analysis 

Table 4 presents a summary of the final disposition status codes of the SBD nodes by 

event type and by specialty for each of the three years. We categorized these disposition codes 

into three categories: complete, refusals, and disavowals. The patterns were generally very 

similar across all three years. In 2003, 37% of all SBD nodes were complete, 15% were refusals 

and 48% were disavowals overall. However, we note substantially different patterns by event 

type. For inpatient stays (IP) 57% of nodes were complete and only 27% were disavowals. All 

of the physician types, with the exception of pathologists, had high rates of completes and 

correspondingly low rates of disavowals for inpatient stays. ER visits had somewhat lower rates 

of complete nodes and higher disavowal rates, with the highest completion rates among 

radiologists and the other specialty category. OP events had the lowest rate of complete SBD 

nodes (27%) and highest rate of disavowals (59%). GP/FPs and OB/GYNs had especially low 

rates of complete nodes and high rates of disavowals for OP events. 

18
 
 

 

6. CONCLUSION 

In this part of the Medicare-MEPS Validation Study, we compared CMS claims data to 

MEPS estimates of SBD expenditures for the set of hospital events identified by households and 

medical providers in the MEPS. The aggregate analyses suggest that SBD expenditures reported 

or imputed for hospital events in the two components of MEPS are 2 to 5 percent lower than the 

Medicare Part B claim amounts for hospital events. The matched pair analyses also show SBD 

expenditures lining up well between MEPS and the CMS claims, particularly for hospital stays. 

Based on the aggregate and matched pair analyses, we conclude that the SBD data collection 

process produces accurate information on expenditures for doctors who bill separately from 

hospitals for their services. Discrepancies in aggregate totals are largely accounted for by 

underreporting of hospital events, especially outpatient department visits, by households. 

 However, we encountered higher than expected abstraction error rates related to facility 

expenditures in the MPC in these comparisons, particularly for OP and ER events. An expert 

panel convened by AHRQ in September 2007 considered some of the issues raised by these 

analyses and made a number of recommendations for improving the accuracy of MPC data 

collection. 

We also examined patterns of disavowal by event type and physician specialty in the 

MPC SBD data. For SBD nodes associated with hospital stays, we found no clear patterns by 

specialty that would allow more selective targeting of data collection. However, among SBD 

nodes associated with OP events, general practitioner/family practice nodes had particularly low 

yield rates, thus showing some potential for streamlined data collection. Selected other 

specialties for OP and ER events also have some potential for streamlining. Future analyses 

may find other potential refinements to improve the efficiency of SDB data collection. 

19
 
REFERENCES 

Machlin SR,Taylor AK. Design, methods, and field results of the 1996 Medical Expenditure 

Panel Survey Medical Provider Component. Rockville (MD):Agency for Healthcare Research 

and Quality; 2000. MEPS Methodology Report No. 9.AHRQ Pub.No. 00-0028. 

Olin GL, Zuvekas SH, Kumar V, et al. Medicare-MEPS Validation Study: A Comparison of 

Hospital and Physician Expenditures. Agency for Healthcare Research and Quality Working 

Paper No. 08003, March 2008, http://gold.ahrq.gov. 

Research Data Assistance Center (RESDAC). Medicare Data File Descriptions. 2006. 

Accessed at http://www.resdac.umn.edu/Medicare/data_file_descriptions.asp on December 4, 

2007. 

20
 
 

 

 

 

 

Table 1. Matched Pairs Sample Selection 

2001 2002 2003

Inpatient Hospital Stays (IP) 

 Matched pairs with complete facility data 266 276 272 

 Matched pairs that match to MEPS HC 229 243 246 

 Matched pairs with <1000 discrepancy in facility payments 194 214 218 

Emergency Room Stays (ER) 

 Matched pairs with complete facility data 234 308 252 

 Matched pairs that match to MEPS HC 143 216 159 

 Matched pairs with <1000 discrepancy in facility payments 142 214 156 

Outpatient Department Visits (OP) 

 Matched pairs with complete facility data 1,999 2,286 2,285 

 Matched pairs that match to MEPS HC 1,280 1,623 1,564 

 Matched pairs with <1000 discrepancy in facility payments 1,255 1,591 1,547 

21
 
Table 2. Aggregate Facilty and SBD Expenditures with Adjustments 

Medicare Payments 

2001 2002 2003 

(n=1,203) (n=1,502) (n=1,340) 

CMS TOTAL 4,778,205 6,115,885 6,046,091 ER 32,043 45,975 49,834 

HS 2,372,564 3,067,087 3,020,464 OP 642,365 918,777 961,277 MV 1,160,351 1,360,377 1,326,470

 Amb surgery 90,524 124,005 110,705 SBD (before adjustments) 570,882 723,669 688,046 - Unmatched HS/ER Facility events (CMS Adjustment #1) -29,260 -31,219 -38,924

 - Unmatched OP Facility events (CMS Adjustment #2) -11,704 -12,488 -15,570

 - SBDs for separately billing labs (CMS Adjustment #3) -5,435 -5,477 -4,650 Adjusted CMS SBD total 524,484 674,484 628,903 

MEPS TOTAL 4,183,749 5,345,646 5,312,302 ER 86,465 121,911 105,120 

HS 2,214,399 2,772,229 2,914,528 OP 415,527 455,306 583,373 MVE (incl SBD) 1,010,159 1,419,800 1,159,860 

MVN 4 49,280 77,454 68,619 

SBD (accounted in PUF) 407,919 498,946 480,802

 + Embedded in MVE (MEPS Adjustment #1) 46,088 78,738 68,460

 + Unmatched MPC Events (MEPS Adjustment #2) 46,489 47,304 52,776 + Embedded in ER/HS/OP Facility pymts (MEPS Adjustment #3) 12,238 14,968 14,424 

Adjusted MEPS SBD total 512,734 639,956 616,462 Ratio of Adjusted MEPS SBD to Adjusted CMS SBD Totals 0.98 0.95 0.98 
2001 2002 

CMS MPC DIFF %DIFF CMS MPC DIFF %DIFF CM

HOSPITAL STAYS 

Number Matched Pairs 194 214 

Facility Payments 1,173,798 1,177,612 3,814 100% 1,462,455 1,475,251 12,796 101% 1,46

SBD Payments 182,544 180,109 (2,435) 99% 232,141 193,461 (38,680) 83% 21

Facility + SBD Payments 1,356,342 1,357,721 1,379 100% 1,694,596 1,668,712 (25,884) 98% 1,68

EMERGENCY DEPARTMENT 

Number Matched Pairs 142 214 

Facility Payments 20,260 27,150 6,890 134% 30,970 37,343 6,373 121% 3

SBD Payments 9,453 10,187 735 108% 16,574 13,145 (3,429) 79% 1

Facility + SBD Payments 29,712 37,337 7,625 126% 47,544 50,488 2,944 106% 4

OUTPATIENT DEPARTMENT 

Number Matched Pairs 1,255 1,591 

Facility Payments 128,669 140,866 12,198 109% 219,674 237,546 17,871 108% 21

SBD Payments 66,963 68,540 1,578 102% 91,143 85,861 (5,282) 94% 9

Facility + SBD Payments 195,631 209,407 13,775 107% 310,818 323,407 12,589 104% 309

Table 3. Medicare Payments for SBDs and Facilities for Matched Pairs of MPC and CMS Claims Events 
926 

 2,589 

 --- 

879 

 86 

 1,726 

 77 

254 

988 

 1,540 

 9,065 

 1,051 

 3,317 

 --- 

 1,033 

 72 

 2,066 

 35 

309 

 1,197 

 1,434 

 1,071 

 2,741 

 --- 

 1,138 

 83 

 2,165 

110 

306 

963 

 1,529 

Table 4. Summary Node Disposition Status by Physician Specialty and Event Type 

2001 ALL EVENTS IP ER 

 Specialty complete refusal disavow TOTAL complete refusal disavow TOTAL complete refusal disavow TOTAL com

 GP/FP 13% 7% 80% 39% 14% 47% 176 11% 6% 83% 151 

 Internist 28% 10% 62% 54% 11% 34% 772 20% 8% 72% 316 

 Pediatrician --- --- --- --- --- --- --- --- --- --- --- 

Surgeon 33% 12% 54% 59% 14% 27% 215 15% 12% 73% 52 

 OB/GYN 19% 3% 78% 57% 7% 36% 14 --- --- --- --- 

 Radiologist 63% 19% 18% 66% 19% 15% 490 68% 23% 10% 299 

 Psychiatrist 19% 5% 75% --- --- --- --- --- --- --- --- 

 Anesthes. 65% 10% 25% 72% 5% 24% 110 --- --- --- --- 

 Pathologist 16% 14% 70% 22% 10% 67% 291 5% 11% 84% 151 

 Other 28% 17% 55% 40% 13% 47% 223 43% 28% 30% 574 

 TOTAL 33% 13% 54% 51% 13% 35% 2,291 35% 18% 47% 1,543 

2002 ALL EVENTS IP ER 

 Specialty complete refusal disavow TOTAL complete refusal disavow TOTAL complete refusal disavow TOTAL com

 GP/FP 11% 10% 79% 40% 16% 44% 158 11% 6% 83% 219 

 Internist 27% 15% 58% 58% 15% 27% 810 16% 15% 68% 292 

 Pediatrician --- --- --- --- --- --- --- --- --- --- --- 

Surgeon 41% 11% 48% 66% 12% 22% 291 23% 11% 66% 56 

 OB/GYN 19% 1% 79% 67% 8% 25% 12 --- --- --- --- 

 Radiologist 58% 22% 19% 62% 22% 16% 582 60% 27% 13% 365 

 Psychiatrist 29% 6% 66% 53% 11% 37% 19 --- --- --- ---  Anesthes. 60% 23% 17% 65% 17% 18% 140 --- --- --- --- 

 Pathologist 14% 15% 71% 21% 18% 61% 304 2% 16% 82% 152 

 Other 35% 24% 40% 56% 10% 34% 238 45% 38% 17% 688 

 TOTAL 33% 17% 50% 10,514 54% 16% 29% 2,554 35% 25% 40% 1,772 

2003 ALL EVENTS IP ER 

 Specialty complete refusal disavow TOTAL complete refusal disavow TOTAL complete refusal disavow TOTAL com

 GP/FP 15% 12% 73% 45% 17% 39% 224 11% 10% 79% 137  Internist 31% 11% 59% 59% 15% 27% 912 19% 6% 74% 263  Pediatrician --- --- --- --- --- --- --- --- --- --- --- 

Surgeon 36% 14% 50% 68% 12% 20% 265 18% 11% 70% 44 

 OB/GYN 17% 6% 77% 62% 15% 23% 13 --- --- --- --- 

 Radiologist 62% 18% 20% 68% 19% 12% 636 61% 23% 15% 311 

 Psychiatrist 29% 3% 68% 63% 0% 38% 16 --- --- --- ---  Anesthes. 58% 22% 21% 58% 20% 22% 144 --- --- --- --- 

 Pathologist 20% 9% 71% 28% 12% 60% 260 4% 11% 85% 122 

 Other 41% 24% 35% 52% 17% 31% 265 60% 19% 21% 607 

 TOTAL 37% 15% 48% 10,106 57% 16% 27% 2,735 43% 16% 42% 1,484 

Note: ---number suppressed to meet CMS privacy guidelines.