MEPS HC-059E: 2001 Emergency Room Visits
January 2004
Agency for Healthcare Research and Quality
Center for Financing, Access, and Cost Trends
540 Gaither Road
Rockville, MD 20850
(301) 427-1406
Table of Contents
A. Data Use Agreement
B. Background
1.0 Household Component
2.0 Medical Provider Component
3.0 Insurance Component
4.0 Survey Management
C. Technical And Programming Information
1.0 General Information
2.0 Data File Information
2.1 Using MEPS Data for Trend and Longitudinal
Analysis
2.2 Codebook Structure
2.3 Reserved Codes
2.4 Codebook Format
2.5 Variable Source and Naming Conventions
2.5.1 General
2.5.2 Expenditure and Source of Payment Variables
2.6 File Contents
2.6.1 Survey Administration Variables
2.6.1.1 Person Identifiers (DUID, PID, DUPERSID)
2.6.1.2 Record Identifiers (EVNTIDX, ERHEVIDX, FFEEIDX)
2.6.1.3 Round Indicator (EVENTRN)
2.6.2 MPC Data Indicator (MPCDATA)
2.6.3 Emergency Room Visit Event Variables
2.6.3.1 Visit Details (ERDATEYR-VSTRELCN)
2.6.3.2 Services, Procedures, and Prescription Medicines (LABTEST-MEDPRESC)
2.6.4 VA Facility (VAPLACE)
2.6.5 Condition and Procedure Codes (ERICD1X-ERICD3X, ERPRO1X), and
Clinical Classification Codes (ERCCC1X-ERCCC3X)
2.6.6 Flat Fee Variables (FFEEIDX, FFERTYPE, FFBEF01, FFTOT02)
2.6.6.1 Definition of Flat Fee Payments
2.6.6.2 Flat Fee Variable Descriptions
2.6.6.2.1 Flat Fee ID (FFEEIDX)
2.6.6.2.2 Flat Fee Type (FFERTYPE)
2.6.6.2.3 Counts of Flat Fee Events that Cross Years
(FFBEF01, FFTOT02)
2.6.6.3 Caveats of Flat Fee Groups
2.6.7 Expenditure Data
2.6.7.1 Definition of Expenditures
2.6.7.2 Data Editing and Imputation Methodologies of
Expenditure Variables
2.6.7.2.1 General Data Editing Methodology
2.6.7.2.2 General Hot-Deck Imputation
2.6.7.2.3 Emergency Room Visit Data Editing and
Imputation
2.6.7.3 Imputation Flag (IMPFLAG)
2.6.7.4 Flat Fee Expenditures
2.6.7.5 Zero Expenditures
2.6.7.6 Discount Adjustment Factor
2.6.7.7 Emergency Room/Hospital Inpatient Stay Expenditures
2.6.7.8 Sources of Payment
2.6.7.9 Imputed Emergency Room Expenditure Variables
2.6.7.9.1 Emergency Room Facility Expenditures
(ERFSF01X-ERFOT01X, ERFXP01X, ERFTC01X)
2.6.7.9.2 Emergency Room Physician Expenditures (ERDSF01X
- ERDOT01X, ERDXP01X, ERDTC01X)
2.6.7.9.3 Total Expenditures and Charges for Emergency
Room Visits (ERXP01X, ERTC01X)
2.6.8 Rounding
3.0 Sample Weight (PERWT01F)
3.1 Overview
3.2 Details on Person Weight Construction
3.2.1 MEPS Panel 5 Weight
3.2.2 MEPS Panel 6 Weight
3.2.3 The Final Weight for 2001
3.2.4 Coverage
4.0 Strategies for Estimation
4.1 Variables with Missing Values
4.2 Basic Estimates of Utilization, Expenditures and Sources of
Payment
4.3 Estimates of the Number of Persons with Emergency Room Visit
Events
4.4 Person-Based Ratio Estimates
4.4.1 Person-Based Ratio Estimates Relative to
Persons with Emergency Room Use
4.4.2 Person-Based Ratio Estimates Relative to the Entire Population
4.5 Sampling Weights for Merging Previous Releases of MEPS
Household Data with this Event File
4.6 Variance Estimation (VARSTR01, VARPSU01)
5.0 Merging/Linking MEPS Data Files
5.1 Merging a 2001 Person-Level File to the 2001
Emergency Room Visit File
5.2 Linking the 2001 Emergency Room Visits File to
the 2001 Medical Conditions File and/or the 2001 Prescribed Medicines File
5.2.1 Limitations/Caveats of RXLK (the Prescribed Medicine Link File)
5.2.2 Limitations/Caveats of CLNK (the Medical Conditions Link File)
References
D. Variable-Source Crosswalk
A. Data Use Agreement
Individual identifiers have been removed from the microdata contained in the
files in this release. Nevertheless, under sections 308 (d) and 903 (c) of the
Public Health Service Act (42 U.S.C. 242m and 42 U.S.C. 299 a-1), data collected
by the Agency for Healthcare Research and Quality (AHRQ) and/or the National
Center for Health Statistics (NCHS) may not be used for any purpose other than
for the purpose for which they were supplied; any effort to determine the
identity of any reported cases is prohibited by law.
Therefore in accordance with the above referenced Federal statute, it is
understood that:
- No one is to use the data in this data set in any way except for
statistical reporting and analysis.
- If the identity of any person or establishment should be discovered
inadvertently, then (a) no use will be made of this knowledge, (b) the
Director, Office of Management, AHRQ will be advised of this incident, (c)
the information that would identify any individual or establishment will
be safeguarded or destroyed, as requested by AHRQ, and (d) no one else
will be informed of the discovered identity.
- No one will attempt to link this data set with individually
identifiable records from any data sets other than the Medical Expenditure
Panel Survey or the National Health Interview Survey.
By using these data you signify your agreement to comply with the
above-stated statutorily based requirements, with the knowledge that
deliberately making a false statement in any matter within the jurisdiction of
any department or agency of the Federal Government violates
Title 18
part 1 Chapter 47 Section 1001 and is punishable by a fine of up to
$10,000 or up to 5 years in prison.
The Agency for Healthcare Research and Quality requests that users cite AHRQ
and the Medical Expenditure Panel Survey as the data source in any publications
or research based upon these data.
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B. Background
The Medical Expenditure Panel Survey (MEPS) provides nationally
representative estimates of health care use, expenditures, sources of payment,
and insurance coverage for the U.S. civilian noninstitutionalized population.
MEPS is cosponsored by the Agency for Healthcare Research and Quality (AHRQ) and
the National Center for Health Statistics (NCHS).
MEPS is a family of three surveys. The Household Component (HC) is the core
survey and forms the basis for the Medical Provider Component (MPC) and part of
the Insurance Component (IC). Together these surveys yield comprehensive data
that provide national estimates of the level and distribution of health care use
and expenditures, support health services research, and can be used to assess
health care policy implications.
MEPS is the third in a series of national probability surveys conducted by
AHRQ on the financing and use of medical care in the United States. The National
Medical Care Expenditure Survey (NMCES) was conducted in 1977, and the National
Medical Expenditure Survey (NMES) was conducted in 1987. Since 1996, MEPS has
continued this series with design enhancements and efficiencies that provide a
more current data resource to capture the changing dynamics of the health care
delivery and insurance systems.
The design efficiencies incorporated into MEPS are in accordance with the
Department of Health and Human Services (DHHS) Survey Integration Plan of June
1995, which focused on consolidating DHHS surveys, achieving cost efficiencies,
reducing respondent burden, and enhancing analytical capacities. To advance
these goals, MEPS includes linkage with the National Health Interview Survey (NHIS)
─ a survey conducted by NCHS from which the sample for the MEPS HC is drawn ─
and enhanced longitudinal data collection for core survey components. The MEPS
HC augments NHIS by selecting a sample of NHIS respondents, collecting
additional data on their health care expenditures, and linking these data with
additional information collected from the respondents' medical providers,
employers, and insurance providers.
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1.0 Household Component
The MEPS HC, a nationally representative survey of the U.S. civilian
noninstitutionalized population, collects medical expenditure data at both the
person and household levels. The HC collects detailed data on demographic
characteristics, health conditions, health status, use of medical care services,
charges and payments, access to care, satisfaction with care, health insurance
coverage, income, and employment.
The HC uses an overlapping panel design in which data are collected through a
preliminary contact followed by a series of five rounds of interviews over a 2 ½
-year period. Using computer-assisted personal interviewing (CAPI) technology,
data on medical expenditures and use for 2 calendar years are collected from
each household. This series of data collection rounds is launched each
subsequent year on a new sample of households to provide overlapping panels of
survey data and, when combined with other ongoing panels, will provide
continuous and current estimates of health care expenditures.
The sampling frame for the MEPS HC is drawn from respondents to NHIS. NHIS
provides a nationally representative sample of the U.S. civilian
noninstitutionalized population, with oversampling of Hispanics and blacks.
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2.0 Medical Provider Component
The MEPS MPC supplements and/or replaces information on medical care events
reported in the MEPS HC by contacting medical providers and pharmacies
identified by household respondents. The MPC sample includes all home health
agencies and pharmacies reported by HC respondents. Office-based physicians,
hospitals, and hospital physicians are also included in the MPC but may be
subsampled at various rates, depending on burden and resources, in certain
years.
Data are collected on medical and financial characteristics of medical and
pharmacy events reported by HC respondents. The MPC is conducted through
telephone interviews and record abstraction.
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3.0 Insurance Component
The MEPS IC collects data on health insurance plans obtained through private
and public-sector employers. Data obtained in the IC include the number and
types of private insurance plans offered, benefits associated with these plans,
premiums, contributions by employers and employees, and employer
characteristics.
Establishments participating in the MEPS IC are selected through three
sampling frames:
- A list of employers or other insurance providers identified by MEPS HC
respondents who report having private health insurance at the Round 1
interview.
- A Bureau of the Census list frame of private-sector business
establishments.
- The Census of Governments from the Bureau of the Census.
To provide an integrated picture of health insurance, data collected from the
first sampling frame (employers and other insurance providers identified by MEPS
HC respondents) are linked back to data provided by those respondents. Data
collected from the two Census Bureau sampling frames are used to produce annual
national and State estimates of the supply and cost of private health insurance
available to American workers and to evaluate policy issues pertaining to health
insurance. National estimates of employer contributions to group health
insurance from the MEPS IC are used in the computation of Gross Domestic Product
(GDP) by the Bureau of Economic Analysis.
The MEPS IC is an annual survey. Data are collected from the selected
organizations through a prescreening telephone interview, a mailed
questionnaire, and a telephone follow-up for nonrespondents.
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4.0 Survey Management
MEPS data are collected under the authority of the Public Health Service Act.
They are edited and published in accordance with the confidentiality provisions
of this act and the Privacy Act. NCHS provides consultation and technical
assistance.
As soon as data collection and editing are completed, the MEPS survey data
are released to the public in staged releases of summary reports, microdata
files, and compendiums of tables. Data are also released through MEPSnet, an
online interactive tool developed to give users the ability to statistically
analyze MEPS data in real time. Summary reports and compendiums of tables are
released as printed documents and electronic files. Microdata files are released
on CD-ROM and/or as electronic files.
Selected printed documents are available through the AHRQ Publications
Clearinghouse. Write or call:
AHRQ Publications Clearinghouse
Attn: (publication number)
P.O. Box 8547
Silver Spring, MD 20907
800-358-9295
410-381-3150 (callers outside the United States only)
888-586-6340 (toll-free TDD service; hearing impaired only)
Be sure to specify the AHRQ number of the document you are requesting.
Additional information on MEPS is available from the MEPS project manager or
the MEPS public use data manager at the Center for Financing, Access and Cost
Trends, Agency for Healthcare Research and Quality, 540 Gaither Road, Rockville,
Md 20850 (301-427-1406).
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C. Technical And Programming Information
1.0 General Information
This documentation describes one in a series of public use event files from
the 2001 Medical Expenditure Panel Survey (MEPS) Household Component (HC) and
Medical Provider Component (MPC). Released as an ASCII data file and a SAS
transport file, the 2001 Emergency Room Visits (EROM) public use event file
provides detailed information on emergency room visits for a nationally
representative sample of the civilian noninstitutionalized population of the
United States. Data from the EROM event file can be used to make estimates of
emergency room utilization and expenditures for calendar year 2001. As
illustrated below, this file consists of MEPS survey data from the 2001 portion
of Round 3, and Rounds 4 and 5 for Panel 5, as well as Rounds 1, 2, and the 2001
portion of Round 3 for Panel 6 (i.e., the rounds for the MEPS panels covering
calendar year 2001).
301 Moved Permanently
301 Moved Permanently
Emergency room events reported in Panel 6 Round 3 and known to have occurred
after December 31, 2001 are not included on this file. In addition to
expenditures, each record contains household reported medical conditions and
procedures associated with the emergency room visit.
Annual counts of emergency room visits are based entirely on household
reports. Information from the MEPS MPC is used to supplement expenditure and
payment data reported by the household, and does not affect use estimates.
Data from the Emergency Room event file can be merged with other 2001 MEPS HC
data files for purposes of appending person-level data such as demographic
characteristics or health insurance coverage to each emergency room record.
This file can also be used to construct summary variables of expenditures,
sources of payment, and related aspects of emergency room visits. Aggregate
annual person-level information on the use of emergency rooms and other health
services use is provided on the MEPS 2001 Full Year Consolidated Data File,
where each record represents a MEPS sampled person.
This documentation offers an overview of the types and levels of data
provided, and the content and structure of the file and the codebook. It
contains the following sections:
Data File Information
Sample Weights
Strategies for Estimation
Merging/Linking MEPS Data Files
References
Variable - Source Crosswalk
Any variables not found on this file but released on previous years' files
were excluded because they contained only missing data.
For more information on MEPS HC survey design see S. Cohen, 1997; J. Cohen,
1997; and S. Cohen, 1996. For information on the MEPS MPC design, see S. Cohen,
1998. Copies of the HC and the MPC survey instruments used to collect the
information on the EROM file are available in the Survey Instrument section of the MEPS web site at the following address: <http://www.meps.ahrq.gov>.
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2.0 Data File Information
The 2001 Emergency Room Visits public use data set consists of one
event-level data file. The file contains characteristics associated with the
EROM event and imputed expenditure data. For users wanting to impute
expenditures, pre-imputed data are available through the Center for Financing,
Access and Cost Trends (CFACT) data center. Please visit the CFACT data center
web site for details: <http://www.meps.ahrq.gov/mepsweb/data_stats/onsite_datacenter.jsp>.
The data user/analyst is forewarned that the imputation of expenditures will
necessitate a sizable commitment of resources: financial, staff, and time.
The 2001 EROM public use data set contains variables and frequency
distributions for 6,444 emergency room visits reported during the 2001 portion
of Round 3 and Rounds 4 and 5 for Panel 5, as well as Rounds 1, 2, and the 2001
portion of Round 3 for Panel 6 of the MEPS Household Component. The file
includes emergency room visit records for all household survey respondents who
resided in eligible responding households and reported at least one emergency
room visit. Records where the emergency room visit was known to have occurred
after December 31, 2001 are not included on this file. Of these 6,444 records, 6,237 were associated with persons having positive
person-level weights (PERWT01F). The persons represented on this file had to
meet either (a) or (b):
- Be classified as a key in-scope person who responded for his or her
entire period of 2001 eligibility (i.e., persons with a positive 2001
full-year person-level weight (PERWT01F > 0)), or
- Be an eligible member of a family all of whose key in-scope
members have a positive person-level weight (PERWT01F > 0). (Such a
family consists of all persons with the same value for FAMIDYR.) That
is, the person must have a positive full-year family-level weight
(FAMWT01F >0). Note that FAMIDYR and FAMWT01F are variables on the
2001 Population Characteristics file.
Persons with no emergency room visits for 2001 are not included on this file
but are represented on the 2001 MEPS person-level file. A codebook for the data
file is provided in files H55CB.PDF and H55CB.ASP.
Each emergency room visit record includes the following: date of the visit;
whether or not person saw doctor; type of care received; type of services (i.e.,
lab test, sonogram or ultrasound, x-rays, etc.) received; medicines prescribed
during the visit; flat fee information; imputed sources of payment; total
payment and total charge; and a full-year person-level weight.
Data from this file can be merged with the MEPS 2001 Full Year Population
Characteristics File using the unique person identifier, DUPERSID, to append
person-level information, such as demographic or health insurance
characteristics, to each record. Emergency room visit events can also be linked
to the MEPS 2001 Medical Conditions File and the MEPS 2001 Prescribed Medicines
File. Please see Section 5.2 and the 2001 Appendix File, HC-059I for details on
how to merge MEPS data files.
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2.1 Using MEPS Data for Trend and Longitudinal Analysis
MEPS began in 1996 and several annual data files have been released. As more
years of data are produced, MEPS will become increasingly valuable for examining
health care trends. However, it is important to consider a variety of factors
when examining trends over time using MEPS. Statistical significance tests
should be conducted to assess the likelihood that observed trends are
attributable to sampling variation. MEPS expenditures estimates are especially
sensitive to sampling variation due to the underlying skewed distribution of
expenditures. For example, 1 percent of the population accounts for about
one-quarter of all expenditures. The extent to which observations with extremely
high expenditures are captured in the MEPS sample varies from year to year
(especially for smaller population subgroups), which can produce substantial
shifts in estimates of means or totals that are simply an artifact of the
sample(s). The length of time being analyzed should also be considered. In
particular, large shifts in survey estimates over short periods of time (e.g.
from one year to the next) that are statistically significant should be
interpreted with caution, unless they are attributable to known factors such as
changes in public policy or MEPS survey methodology. Looking at changes over
longer periods of time can provide a more complete picture of underlying trends.
Analysts may wish to consider using techniques to smooth or stabilize trends
analyses of MEPS data such as pooling time periods for comparison (e.g. 1996-97
versus 1998-99), working with moving averages, or using modeling techniques with
several consecutive years of MEPS data to test the fit of specified patterns
over time. Finally, researchers should be aware of the impact of multiple
comparisons on Type I error because performing numerous statistical significance
tests of trends increases the likelihood of inappropriately concluding a change
is statistically significant.
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2.2 Codebook Structure
For each variable on the Emergency Room Events event file, both weighted and
unweighted frequencies are provided in the codebook (H59ECB.PDF and H59ECB.ASP).
The codebook and data file sequence list variables in the following order:
Unique person identifiers
Unique emergency room event identifiers
Emergency room characteristic variables
ICD-9-CM condition and procedure codes
Clinical Classification Software (CCS) codes
Imputed expenditure variables
Weight and variance estimation variables
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2.3 Reserved Codes
The following reserved code values are used:
Value |
Definition |
-1 INAPPLICABLE |
Question was not asked due to skip pattern. |
-7 REFUSED |
Question was asked and respondent refused to answer question. |
-8 DK |
Question was asked and respondent did not know answer. |
-9 NOT ASCERTAINED |
Interviewer did not record the data. |
Generally, values of -1, -7, -8, and -9 for non-expenditure variables have
not been edited on this file. The values of -1 and -9 can be edited by the data
users/analysts by following the skip patterns in the HC survey questionnaire
(located on the MEPS web site: <http://www.meps.ahrq.gov/mepsweb/survey_comp/survey.jsp>).
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2.4 Codebook Format
The EROM codebook describes an ASCII data set (although the data are also
being provided in a SAS transport file). The following codebook items are
provided for each variable:
Identifier |
Description |
Name |
Variable name (maximum of 8 characters) |
Description |
Variable descriptor (maximum of 40 characters) |
Format |
Number of bytes |
Type |
Type of data: numeric (indicated by NUM) or character (indicated by CHAR) |
Start |
Beginning column position of variable in record |
End |
Ending column position of variable in record |
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2.5 Variable Source and Naming Conventions
In general, variable names reflect the content of the variable, with an
eight-character limitation. All imputed/edited variables end with an "X".
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2.5.1 General
Variables on this file were derived from the HC questionnaire itself, derived
from the MPC data collection instrument, derived from CAPI, or assigned in
sampling. The source of each variable is identified in Section D "Variable -
Source Crosswalk" in one of four ways:
- Variables derived from CAPI or assigned in sampling are indicated as
"CAPI derived" or "Assigned in sampling," respectively;
- Variables which come from one or more specific questions have those
questionnaire sections and question numbers indicated in the "Source"
column; questionnaire sections are identified as:
- ER - Emergency Room Section
- FF - Flat Fee Section
- CP - Charge Payment Section;
- Variables constructed from multiple questions using complex algorithms
are labeled "Constructed" in the "Source" column; and
- Variables which have been edited or imputed are so indicated.
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2.5.2 Expenditure and Source
of Payment Variables
The names of the expenditure and source of payment variables follow a
standard convention, are eight characters in length, and end in an "X"
indicating edited/imputed. Please note that imputed means that a series of
logical edits, as well as an imputation process to account for missing data,
have been performed on the variable.
The total sum of payments and the 12 source of payment variables are named in
the following way:
The first two characters indicate the type of event:
IP - inpatient stay |
OB - office-based visit |
ER - emergency room visit |
OP - outpatient visit |
HH - home health visit |
DV - dental visit |
OM - other medical equipment |
RX - prescribed medicine |
For expenditure variables on these files, the third character indicates
whether the expenditure is associated with the facility (F) or the physician
(D).
In the case of the source of payment variables, the fourth and fifth
characters indicate:
SF - self or family |
OF - other Federal Government |
MR - Medicare |
SL - State/local government |
MD - Medicaid |
WC - Workers' Compensation |
PV - private insurance |
OT - other insurance |
VA - Veterans |
OR - other private |
TR - TRICARE |
OU - other public |
|
XP - sum of payments |
In addition, the total charge variable is indicated by TC in the variable
name.
The sixth and seventh characters indicate the year (01). The eighth
character, "X", indicates whether the variable is edited/imputed.
For example, ERFSF01X is the edited/imputed amount paid by self or family for
the facility portion of the expenditure associated with an emergency room visit.
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2.6 File Contents
2.6.1 Survey Administration
Variables
2.6.1.1 Person Identifiers (DUID, PID, DUPERSID)
The dwelling unit ID (DUID) is a five-digit random number assigned after the
case was sampled for MEPS. The three-digit person number (PID) uniquely
identifies each person within the dwelling unit. The eight-character variable
DUPERSID uniquely identifies each person represented on the file and is the
combination of the variables DUID and PID. For detailed information on dwelling
units and families, please refer to the documentation for the 2001 Full Year
Population Characteristics File.
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2.6.1.2 Record Identifiers (EVNTIDX, ERHEVIDX, FFEEIDX)
EVNTIDX uniquely identifies each emergency room visit/event (i.e., each
record on the Emergency Room visit file) and is the variable required to link
emergency room events to data files containing details on conditions and/or
prescribed medicines (MEPS 2001 Medical Conditions File and the MEPS 2001
Prescribed Medicines File, respectively). For details on linking, see Section
5.2 or the MEPS 2001 Appendix File, HC-059I.
ERHEVIDX is a constructed variable identifying an EROM record that has its
facility expenditures represented on an associated hospital inpatient stay
record. This variable was constructed by comparing date information for the
reported hospital stay and all emergency room visits for the same person. On the
2001 EROM file, there are 522 emergency room events linked to subsequent
hospital stays. Please note that where the emergency room visit is associated
with a hospital stay (and its expenditures and charges are included with the
hospital stay), the physician expenditures associated with the emergency room
visit remain on the Emergency Room file.
FFEEIDX is a constructed variable which uniquely identifies a flat fee group,
that is, all events that were a part of a flat fee payment.
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2.6.1.3 Round Indicator (EVENTRN)
EVENTRN indicates the round in which the emergency room visit was reported.
Please note: Rounds 3, 4, and 5 are associated with MEPS survey data collected
from Panel 5. Likewise, Round 1, 2, and 3 are associated with data collected
from Panel 6.
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2.6.2 MPC Data Indicator (MPCDATA)
MPCDATA is a constructed variable which indicates whether or not MPC data
were collected for the emergency room visit. While all emergency room events are
sampled into the Medical Provider Component, not all emergency room event
records have MPC data associated with them. This is dependent upon the
cooperation of the household respondent to provide permission forms to contact
the emergency room facility as well as the cooperation of the emergency room
facility to participate in the survey.
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2.6.3 Emergency Room Visit
Event Variables
This file contains variables describing emergency room visits/events reported
by household respondents in the Emergency Room section of the MEPS HC
questionnaire. The questionnaire contains specific probes for determining
details about the emergency room event. These variables have not been edited.
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2.6.3.1 Visit Details (ERDATEYR-VSTRELCN)
When a person reported having had a visit to the emergency room, the date of
the emergency room visit was recorded (ERDATEYR, ERDATEMM, ERDATEDD). Also
reported is whether or not the person saw a medical doctor (SEEDOC). The type of
care the person received (VSTCTGRY) and whether or not the visit was related to
a specific condition (VSTRELCN) were also determined.
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2.6.3.2 Services, Procedures, and Prescription
Medicines (LABTEST-
MEDPRESC)
Services received during the visit included whether or not the person
received lab tests (LABTEST), a sonogram or ultrasound (SONOGRAM), x-rays (XRAYS),
a mammogram (MAMMOG), an MRI or CAT scan (MRI), an electrocardiogram (EKG), an
electroencephalogram (EEG), a vaccination (RCVVAC), anesthesia (ANESTH), or
other diagnostic tests or exams (OTHSVCE). Whether or not a surgical procedure
was performed during the visit was asked (SURGPROC). The questionnaire
determined if a medicine was prescribed for the person during the emergency room
visit (MEDPRESC). See Section 5.2 for information on linking to the prescription
medicine events file.
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2.6.4 VA Facility (VAPLACE)
VAPLACE is a constructed variable that indicates whether the service was
provided at a VA facility. This variable only has valid data for providers that
were sampled into the Medical Provider Component. All other providers are
classified as "No".
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2.6.5 Condition and Procedure
Codes (ERICD1X-ERICD3X, ERPRO1X), and Clinical Classification Codes
(ERCCC1X-ERCCC3X)
Information on household reported medical conditions and procedures
associated with each emergency room visit are provided on this file. There are
up to three condition and CCS codes (ERICD1X-ERICD3X, ERCCC1X-ERCCC3X) and one
procedure code (ERPRO1X) listed for each emergency room visit. In order to
obtain complete condition information associated with an event, the data
user/analyst must link to the MEPS 2001 Medical Conditions File. Details on how
to link the 2001 EROM event file to the MEPS 2001 Medical Conditions File are
provided in Section 5.2. and the MEPS 2001 Appendix File, HC-059I. The
data user/analyst should note that because of confidentiality restrictions,
provider-reported condition information is not publicly available.
The medical conditions and procedures reported by the Household Component
respondent were recorded by the interviewer as verbatim text, which were then
coded to fully-specified 2001 ICD-9-CM codes, including medical conditions and V
codes (Health Care Financing Administration, 1980) by professional coders.
Although codes were verified and error rates did not exceed 2.5 percent for any
coder, data users/analysts should not presume this level of precision in the
data; the ability of household respondents to report condition data that can be
coded accurately should not be assumed (Cox and Cohen, 1985; Cox and Iachan,
1987; Edwards, et al, 1994; and Johnson and Sanchez, 1993). For detailed
information on how conditions and procedures were coded, please refer to the
documentation on the MEPS 2001 Medical Conditions File. For frequencies of
conditions by event type, please see the MEPS 2001 Appendix File, HC-059I.
The ICD-9-CM condition codes were aggregated into clinically meaningful
categories. These categories, included on the file as ERCCC1X-ERCCC3X, were
generated using Clinical Classification Software [formerly known as Clinical
Classifications for Health Care Policy Research (CCHPR)], (Elixhauser, et al.,
1998), which aggregates conditions and V-codes into 260 mutually exclusive
categories, most of which are clinically homogeneous.
In order to preserve respondent confidentiality, nearly all of the condition
codes provided on this file have been collapsed from fully-specified codes to
three-digit code categories. The reported ICD-9-CM code values were mapped to
the appropriate clinical classification category prior to being collapsed to the
three-digit categories. Details on this procedure are outlined in the 2001
Medical Conditions File.
The condition codes (and clinical classification codes) and procedure codes
linked to each emergency room visit are sequenced in the order in which the
conditions were reported by the household respondent, which was in order of
input into the database and not in order of importance or severity. Data
users/analysts who use the MEPS 2001 Medical Conditions File in conjunction with
this emergency room visits file should note that the order of conditions on this
file is not identical to that on the Medical Conditions file.
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2.6.6 Flat Fee Variables (FFEEIDX, FFERTYPE, FFBEF01,
FFTOT02)
2.6.6.1 Definition of
Flat Fee Payments
A flat fee is the fixed dollar amount a person is charged for a package of
health care services provided during a defined period of time. Examples would
be: obstetrician's fee covering a normal delivery, as well as pre- and
post-natal care; or a surgeon's fee covering surgical procedure and
post-surgical care. A flat fee group is the set of medical services (i.e.,
events) that are covered under the same flat fee payment. The flat fee groups
represented on this file include flat fee groups where at least one of the
health care events, as reported by the HC respondent, occurred during 2001. By
definition, a flat fee group can span multiple years. Furthermore, a single
person can have multiple flat fee groups.
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2.6.6.2 Flat Fee Variable Descriptions
2.6.6.2.1 Flat Fee ID (FFEEIDX)
As noted earlier in Section 2.5.1.2 "Record Identifiers," the variable
FFEEIDX uniquely identifies all events that are part of the same flat fee group
for a person. On any 2001 MEPS event file, every event that is part of a
specific flat fee group will have the same value for FFEEIDX. Note that
prescribed medicine and home health events are never included in a flat fee
group and FFEEIDX is not a variable on those event files.
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2.6.6.2.2 Flat Fee Type (FFERTYPE)
FFERTYPE indicates whether the 2001 emergency room visit is the "stem" or
"leaf" of a flat fee group. A stem (records with FFERTYPE = 1) is the initial
medical service (event) which is followed by other medical events that are
covered under the same flat fee payment. The leaves of the flat fee group
(records with FFERTYPE = 2) are those medical events that are tied back to the
initial medical event (the stem) in the flat fee group. These "leaf" records
have their expenditure variables set to zero. For the emergency room visits that
are not part of a flat fee payment, the FFERTYPE is set to -1, "INAPPLICABLE."
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2.6.6.2.3 Counts of Flat Fee Events that Cross
Years (FFBEF01, FFTOT02)
As described in Section 2.6.6.1, a flat fee
payment may cover multiple events, and the multiple events could span multiple
years. For situations where the emergency room event occurred in 2001 as part of
a group of events, and some event occurred before or
after 2001, counts of the known events are provided on the emergency room
record. Variables indicating events that occurred before or after 2001 are as
follows:
FFBEF01 - total number of pre-2001 events in the same flat fee group as
the 2001 emergency room visit(s). This count would not include the 2001
emergency room visit(s). Because there were no 2000 events expected for any
flat fee group, this variable was omitted from the 2001 ER file.
FFTOT02 - indicates the number of 2002 emergency room visits, expected to
be in the same flat fee group as the emergency room event that occurred in
2001. Because there were no 2002 events expected for any flat fee group,
this variable was omitted from the 2001 ER file.
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2.6.6.3 Caveats of Flat Fee Groups
There are 61 emergency room visits that are identified as being part of a
flat fee payment group. In general, every flat fee group should have an initial
visit (stem) and at least one subsequent visit (leaf). There are some situations
where this is not true. For some flat fee groups, the initial visit reported
occurred in 2001, but the remaining visits that were part of this flat fee group
occurred in 2002. In this case, the 2001 flat fee group represented on this file
would consist of one event, the stem. The 2002 events that are part of this flat
fee group are not represented on the file. Similarly, the household respondent
may have reported a flat fee group where the initial visit began in 2000 but
subsequent visits occurred during 2001. In this case, the initial visit would
not be represented on the file. This 2001 flat fee group would then only consist
of one or more leaf records and no stem.
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2.6.7
Expenditure Data
2.6.7.1 Definition of Expenditures
Expenditures on this file refer to what is paid for health care services.
More specifically, expenditures in MEPS are defined as the sum of payments for
care received for each emergency room visit, including out-of-pocket payments
and payments made by private insurance, Medicaid, Medicare and other sources.
The definition of expenditures used in MEPS differs slightly from its
predecessors: the 1987 NMES and 1977 NMCES surveys where "charges" rather than
sum of payments were used to measure expenditures. This change was adopted
because charges became a less appropriate proxy for medical expenditures during
the 1990's due to the increasingly common practice of discounting. Although
measuring expenditures as the sum of payments incorporates discounts in the MEPS
expenditure estimates, the estimates do not incorporate any payment not directly
tied to specific medical care visits, such as bonuses or retrospective payment
adjustments by third party payers. Another general change from the two prior
surveys is that charges associated with uncollected liability, bad debt, and
charitable care (unless provided by a public clinic or hospital) are not counted
as expenditures because there are no payments associated with those
classifications. While charge data are provided on this file, data
users/analysts should use caution when working with this data because a charge
does not typically represent actual dollars exchanged for services or the
resource costs of those services; nor are they directly comparable to the
expenditures defined in the 1987 NMES. For details on expenditure definitions,
please reference "Informing American Health Care Policy" (Monheit et al., 1999).
AHRQ has developed factors to apply to the 1987 NMES expenditure data to
facilitate longitudinal analysis. These factors can be assessed via the CFACT
data center. For more information, see the data center section of the MEPS web
site <http://www.meps.ahrq.gov>.
Expenditure data related to emergency room visits are broken out by facility
and separately billing doctor expenditures. This file contains six categories of
expenditure variables per visit: basic hospital emergency room facility
expenses; expenses for doctors who billed separately from the hospital for any
emergency room services provided during the emergency room visit; total
expenses, which is the sum of the facility and physician expenses; facility
charge; physician charge, total charges, which is the sum of the facility and
physician charges. If examining trends in MEPS expenditures or performing
longitudinal analysis on MEPS expenditures, please refer to section C,
sub-section 2.1 for more information.
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2.6.7.2 Data Editing and Imputation Methodologies of
Expenditure Variables
The expenditure data included on this file were derived from both the MEPS
Household (HC) and Medical Provider Component (MPC). The MPC contacted medical
providers identified by household respondents. The charge and payment data from
medical providers were used in the expenditure imputation process to supplement
missing household data. For all emergency room visits, MPC data were used if
complete; otherwise, HC data were used if complete. Missing data for emergency
room visits, where HC data were not complete and MPC data were not collected or
complete, were imputed through the imputation process.
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2.6.7.2.1 General Data Editing Methodology
Logical edits were used to resolve internal inconsistencies and other
problems in the HC and MPC survey-reported data. The edits were designed to
preserve partial payment data from households and providers, and to identify
actual and potential sources of payment for each household-reported event. In
general, these edits accounted for outliers, copayments or charges reported as
total payments, and reimbursed amounts that were reported as out-of-pocket
payments. In addition, edits were implemented to correct for mis-classifications
between Medicare and Medicaid and between Medicare HMOs and private HMOs as
payment sources. These edits produced a complete vector of expenditures for some
events, and provided the starting point for imputing missing expenditures in the
remaining events.
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2.6.7.2.2 General Hot-Deck Imputation
A weighted sequential hot-deck procedure was used to impute missing
expenditures as well as total charge. This procedure uses survey data from
respondents to replace missing data while taking into account the respondents'
weighted distribution in the imputation process. Classification variables vary
by event type in the hot-deck imputations, but total charge and insurance
coverage are key variables in all of the imputations. Separate imputations were
performed for nine categories of medical provider care: inpatient hospital
stays, outpatient hospital department visits, emergency room visits, visits to
physicians, visits to non-physician providers, dental services, home health care
by certified providers, home health care by paid independents, and other medical
expenses. Within each event type file, separate imputations were performed for
flat fee and simple events. After the imputations were finished, visits to
physician and non-physician providers were combined into a single medical
provider file. The two categories of home care also were combined into a single
home health file.
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2.6.7.2.3 Emergency
Room Visit Data Editing and Imputation
Facility expenditures for emergency room services were developed in a
sequence of logical edits and imputations. "Household" edits were applied to
sources and amounts of payment for all events reported by HC respondents. "MPC"
edits were applied to provider-reported sources and amounts of payment for
records matched to household-reported events. Both sets of edits were used to
correct obvious errors in the reporting of expenditures. After the data from
each source were edited, a decision was made as to whether household- or MPC-reported
information would be used in the final editing and hot-deck imputations for
missing expenditures. The general rule was that MPC data would be used where a
household-reported event corresponded to an MPC-reported event (i.e., a matched
event), since providers usually have more complete and accurate data on sources
and amounts of payment than households.
One of the more important edits separated flat fee events from simple events.
This edit was necessary because groups of events covered by a flat fee (i.e., a
flat fee bundle) were edited and imputed separately from individual events
covered by a single charge (i.e., simple events). Most emergency room events
were imputed as simple events because hospital facility charges are rarely
bundled with other events. (See Section 2.6.6 for more details on flat fee
groups). However, some emergency room visits were treated as free events because
the respondent was admitted to a hospital through its emergency room. In these
cases, emergency room charges are included in the charge for an inpatient
hospital stay.
Logical edits also were used to sort each event into a specific category for
the imputations. Events with complete expenditures were flagged as potential
donors for the hot-deck imputations, while events with missing expenditure data
were assigned to various recipient categories. Each event with missing
expenditure data was assigned to a recipient category based on the extent of its
missing charge and expenditure data. For example, an event with a known total
charge but no expenditure information was assigned to one category, while an
event with a known total charge and partial expenditure information was assigned
to a different category. Similarly, events without a known total charge and no
or partial expenditure information were assigned to various recipient
categories.
The logical edits produced eight recipient categories in which all events had
a common extent of missing data. Separate hot-deck imputations were performed on
events in each recipient category, and the donor pool was restricted to events
with complete expenditures from the MPC. The donor pool restriction was used
even though some unmatched events had complete household-reported expenditures.
These events were not allowed to donate information to other events because the
MPC data were considered to be more reliable.
The donor pool included "free events" because, in some instances, providers
are not paid for their services. These events represent charity care, bad debt,
provider failure to bill, and third party payer restrictions on reimbursement in
certain circumstances. If free events were excluded from the donor pool, total
expenditures would be over-counted because the distribution of free event among
complete events (donors) is not represented among incomplete events
(recipients).
Expenditures for some emergency room visits are not shown because the person
was admitted to the hospital through the emergency room. These emergency room
events are not free, but the expenditures are included in the inpatient stay
expenditures. The variable ERHEVIDX can be used to differentiate between free
emergency room care and situations where the emergency room charges have been
included in the inpatient hospital charges.
Expenditures for services provided by separately billing doctors in hospital
settings were also edited and imputed. These expenditures are shown separately
from hospital facility charges for hospital inpatient, outpatient, and emergency
room care.
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2.6.7.3 Imputation Flag (IMPFLAG)
IMPFLAG is a six-category variable that indicates if the event contains
complete Household Component (HC) or Medical Provider Component (MPC) data, was
fully or partially imputed, or was imputed in the capitated imputation process
(for OP and MV events only). The following list identifies how the imputation
flag is coded; the categories are mutually exclusive.
IMPFLAG=0 not eligible for imputation (includes zeroed out and
flat fee leaf events)
IMPFLAG=1 complete HC data
IMPFLAG=2 complete MPC data
IMPFLAG=3 fully imputed
IMPFLAG=4 partially imputed
IMPFLAG=5 complete MPC data through capitation imputation (not
applicable to ER events)
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2.6.7.4 Flat Fee Expenditures
The approach used to count expenditures for flat fees was to place the
expenditure on the first visit of the flat fee group. The remaining visits have
zero facility payments, while physician's expenditures may be still present.
Thus, if the first visit in the flat fee group occurred prior to 2001, all of
the events that occurred in 2001 will have zero payments. Conversely, if the
first event in the flat fee group occurred at the end of 2001, the total
expenditure for the entire flat fee group will be on that event, regardless of
the number of events it covered after 2001. See Section 2.5.3 for details on the
flat fee variables.
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2.6.7.5 Zero Expenditures
There are some medical events reported by respondents where the payments were
zero. This could occur for several reasons including (1) free care was provided,
(2) bad debt was incurred, (3) care was covered under a flat fee arrangement
beginning in an earlier year, (4) follow-up visits were provided without a
separate charge (e.g., after a surgical procedure), or (5) emergency room visit
expenditures were included on the linked hospital record. If all of the medical
events for a person fell into one of these categories, then the total annual
expenditures for that person would be zero.
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2.6.7.6 Discount Adjustment Factor
An adjustment was also applied to some HC-reported expenditure data because
an evaluation of matched HC/MPC data showed that respondents who reported that
charges and payments were equal were often unaware that insurance payments for
the care had been based on a discounted charge. To compensate for this
systematic reporting error, a weighted sequential hot-deck imputation procedure
was implemented to determine an adjustment factor for HC-reported insurance
payments when charges and payments were reported to be equal. As for the other
imputations, selected predictor variables were used to form groups of donor and
recipient events for the imputation process.
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2.6.7.7 Emergency Room/Hospital Inpatient Stay
Expenditures
It is common for an emergency room visit to result in a hospital stay.
However, while it is true that all of the event files can be linked by DUPERSID,
there is no unique record link between hospital inpatient stays and emergency
room visits. However, wherever this relationship could be identified (using MPC
start and end dates of the events as well as other information from the
provider), the facility expenditure associated with the emergency room visit is
included in the hospital facility expenditure. Hence, the expenditures (and
charges) for some emergency room visits are included in the resulting
hospitalization. In these situations, the emergency room record on this file
will have its expenditure (and charge) information zeroed out to avoid
double-counting while its corresponding hospital inpatient stay record on the
MEPS 2001 Hospital Inpatient Stays File will have the combined expenditures.
Please note that any physician expenditures associated with emergency room
events remain on the Emergency Room event file. The variable ERHEVIDX identifies
the emergency room visits whose expenditures are included in the expenditures
for the following hospital inpatient stay. It should also be noted that for
these cases there is only one emergency room stay associated with the hospital
room stay.
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2.6.7.8 Sources of Payment
In addition to total expenditures, variables are provided which itemize
expenditures according to major source of payment categories. These categories
are:
- Out-of-pocket by user or family,
- Medicare,
- Medicaid,
- Private Insurance,
- Veterans Administration, excluding TRICARE,
- TRICARE,
- Other Federal sources - includes Indian Health
Service, Military Treatment Facilities, and other care by the Federal
government,
- Other State and Local Source - includes community and
neighborhood clinics, State and local health departments, and State programs
other than Medicaid,
- Workers' Compensation, and
- Other Unclassified Sources - includes sources such as
automobile, homeowner's, and liability insurance, and other miscellaneous or
unknown sources.
Two additional source of payment variables were created to classify payments
for events with apparent inconsistencies between health insurance coverage and
sources of payment based on data collected in the survey. These variables
include:
- Other Private - any type of private insurance
payments reported for persons not reported to have any private health
insurance coverage during the year as defined in MEPS, and
- Other Public - Medicare/Medicaid payments reported
for persons who were not reported to be enrolled in the Medicare/Medicaid
program at any time during the year.
Though relatively small in magnitude, data users/analysts should exercise
caution when interpreting the expenditures associated with these two additional
sources of payment. While these payments stem from apparent inconsistent
responses to health insurance and source of payment questions in the survey,
some of these inconsistencies may have logical explanations. For example,
private insurance coverage in MEPS is defined as having a major medical plan
covering hospital and physician services. If a MEPS sampled person did not have
such coverage but had a single service type insurance plan (e.g., dental
insurance) that paid for a particular episode of care, those payments may be
classified as "other private." Some of the "other public" payments may stem from
confusion between Medicaid and other state and local programs or may be from
persons who were not enrolled in Medicaid, but were presumed eligible by a
provider who ultimately received payments from the public payer.
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2.6.7.9 Imputed Emergency Room Expenditure Variables
This file contains two sets of imputed expenditure variables: facility
expenditures and physician expenditures.
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2.6.7.9.1 Emergency Room Facility Expenditures
(ERFSF01X-ERFOT01X, ERFXP01X, ERFTC01X)
Emergency room expenses include all expenses for treatment, services, tests,
diagnostic and laboratory work, x-rays, and similar charges, as well as any
physician services included in the emergency room charge.
ERFSF01X - ERFOT01X are the 12 sources of payment. ERFTC01X is the total
charge, and ERFXP01X is the sum of the 12 sources of payment for the Emergency
Room expenditures. The 12 sources of payment are: self/family (ERFSF01X),
Medicare (ERFMR01X), Medicaid (ERFMD01X), private insurance (ERFPV01X), Veterans
Administration (ERFVA01X), TRICARE (ERFTR01X), other Federal sources (ERFOF01X),
State and Local (non-federal) government sources (ERFSL01X), Worker's
Compensation (ERFWC01X), other private insurance (ERFOR01X), other public
insurance (ERFOU01X), and other insurance (ERFOT01X). Please note that where an
emergency room visit record is linked to a hospital inpatient stay record,
ERFTC01X has been zeroed out.
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2.6.7.9.2 Emergency Room Physician
Expenditures (ERDSF01X - ERDOT01X, ERDXP01X, ERDTC01X)
Separately billing doctor (SBD) expenses typically cover services provided to
patients in hospital settings by providers like anesthesiologists, radiologists,
and pathologists, whose charges are often not included in emergency room visit
bills.
For physicians who bill separately (i.e., outside the emergency room visit
bill), a separate data collection effort within the Medical Provider Component
was performed to obtain this same set of expenditure information from each
separately billing doctor. It should be noted that there could be several
separately billing doctors associated with a medical event. For example, an
emergency room visit could have a radiologist and an internist associated with
it. If their services are not included in the emergency room visit bill then
this is one medical event with 2 separately billing doctors. The imputed
expenditure information associated with the separately billing doctors was
summed to the event level and is provided on the file. ERDSF01X - ERDOT01X are
the 12 sources of payment, ERDXP01X is the sum of the 12 sources of payments,
and ERDTC01X is the total charge.
Data users/analysts need to take into consideration whether to analyze
facility and SBD expenditures separately, combine them within service
categories, or collapse them across service categories (e.g., combine SBD
expenditures with expenditures for physician visits to offices and/or outpatient
departments).
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2.6.7.9.3 Total Expenditures and Charges for
Emergency Room Visits (ERXP01X, ERTC01X)
Data users/analysts interested in total expenditure should use the variable
ERXP01X, which includes both the facility and physician amounts. Those
interested in total charges should use the variable ERTC01X (see section 2.5.7.1
for an explanation of the "charge" concept). However, please note that where the
emergency room visit is linked to a hospital inpatient stay record, ERFTC01X has
been zeroed out. Thus, ERTC01X may be equal to "0" or the doctor total charge
(ERDTC01X).
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2.6.8 Rounding
The expenditure variables have been rounded to the nearest penny.
Person-level expenditure information released on the MEPS 2001 Person Level Use
and Expenditure File were rounded to the nearest dollar. It should be noted that
using the MEPS 2001 event files to create person-level totals will yield
slightly different totals than those found on the person-level expenditure file.
These differences are due to rounding only. Moreover, in some instances, the
number of persons having expenditures on the event files for a particular source
of payment may differ from the number of persons with expenditures on the
person-level expenditures file for that source of payment. This difference is
also an artifact of rounding only. Please see the MEPS 2001 Appendix File,
HC-059I, for details on such rounding differences.
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3.0 Sample Weight
(PERWT01F)
3.1 Overview
There is a single full year person-level weight (PERWT01F) assigned to each
record for each key, in-scope person who responded to MEPS for the full period
of time that he or she was in-scope during 2001. A key person either was a
member of an NHIS household at the time of the NHIS interview, or became a
member of a family associated with such a household after being out-of-scope at
the time of the NHIS (examples of the latter situation include newborns and
persons returning from military service, an institution, or living outside the
United States). A person is in-scope whenever he or she is a member of the
civilian noninstitutionalized portion of the U.S. population.
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3.2 Details on Person Weight Construction
The person-level weight PERWT01F was developed in several stages.
Person-level weights for Panels 5 and 6 were created separately. The weighting
process for each panel included an adjustment for nonresponse over time and
poststratification. Poststratification was achieved initially by controlling to
Current Population Survey (CPS) population estimates based on five variables.
The five variables used in the establishment of the initial person-level
poststratification control figures were: census region (Northeast, Midwest,
South, West); MSA status (MSA, non-MSA); race/ethnicity (Hispanic, black but
non-Hispanic, and other); sex; and age. A 2001 composite weight was then formed
by multiplying each weight from Panel 5 by the factor (1/3) and each weight from
Panel 6 by the factor (2/3). The choice of factors reflected the relative sample
sizes of the two panels, helping to limit the variance of estimates obtained
from pooling the two samples. The composite weight was then poststratified to
the same set of CPS-based control totals. When poverty status information
derived from income variables became available, a final poststratification was
done on the previously established weight variable. Control totals were
established based on poverty status (below poverty, from 100 to 125 percent of
poverty, from 125 to 200 percent of poverty, from 200 to 400 percent of poverty,
at least 400 percent of poverty) as well as the original five poststratification
variables.
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3.2.1 MEPS Panel 5 Weight
The person-level weight for MEPS Panel 5 was developed using the 2000 full
year weight for an individual as a "base" weight for survey participants present
in 2000. For key, in-scope respondents who joined an RU some time in 2001 after
being out-of-scope in 2000, the 2000 family weight associated with the family
the person joined served as a "base" weight. The weighting process included an
adjustment for nonresponse over Rounds 4 and 5 as well as poststratification to
population control figures for December 2001. These control figures were derived
by scaling back the population totals obtained from the March 2001 CPS to
reflect the December 2001 CPS estimated population distribution across age and
sex categories as of December 2001. Variables used in the establishment of
person-level poststratification control figures included: census region
(Northeast, Midwest, South, West); MSA status (MSA, non-MSA); race/ethnicity
(Hispanic, black but non-Hispanic, and other); sex; and age. Overall, the
weighted population estimate for the civilian noninstitutionalized population on
December 31, 2001 is 280,791,812. Key, responding persons not in-scope on
December 31, 2001 but in-scope earlier in the year retained, as their final
Panel 5 weight, the weight after the nonresponse adjustment.
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3.2.2 MEPS Panel 6 Weight
The person-level weight for MEPS Panel 6 was developed using
the MEPS Round 1 person-level weight as a "base" weight. For key, in-scope
respondents who joined an RU after Round 1, the Round 1 family weight served as
a "base" weight. The weighting process included an adjustment for nonresponse
over Round 2 and the 2001 portion of Round 3 as well as poststratification to
the same population control figures for December 2001 used for the MEPS Panel 5
weights. The same five variables employed for Panel 5 poststratification (census
region, MSA status, race/ethnicity, sex, and age) were used for Panel 6
poststratification. Similarly, for Panel 6, key, responding persons not in-scope
on December 31, 2001 but in-scope earlier in the year retained, as their final
Panel 6 weight, the weight after the nonresponse adjustment.
Note that the MEPS Round 1 weights (for both panels with one exception as
noted below) incorporated the following components: the original household
probability of selection for the NHIS; ratio-adjustment to NHIS-based national
population estimates at the household (occupied dwelling unit) level; adjustment
for nonresponse at the dwelling unit level for Round 1; and poststratification
to figures at the family and person level obtained from the March 2001 CPS data
base.
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3.2.3 The Final Weight for
2001
Variables used in the establishment of person-level poststratification
control figures included: poverty status (below poverty, from 100 to 125 percent
of poverty, from 125 to 200 percent of poverty, from 200 to 400 percent of
poverty, at least 400 percent of poverty); census region (Northeast, Midwest,
South, West); MSA status (MSA, non-MSA); race/ethnicity (Hispanic, black but
non-Hispanic, and other); sex; and age. Overall, the weighted population
estimate for the civilian noninstitutionalized population for December 31, 2001
is 280,791,812 (PERWT01F>0 and INSC1231=1). The weights of some persons
out-of-scope on December 31, 2001 were also poststratified. Specifically, the
weights of persons out-of-scope on December 31, 2001 who were in-scope some time
during the year and also entered a nursing home during the year were
poststratified to a corresponding control total obtained from the 1996 MEPS
Nursing Home Component. The weights of persons who died while in-scope during
2001 were poststratified to corresponding estimates derived using data obtained
from the Medicare Current Beneficiary Survey (MCBS) and Vital Statistics
information provided by the National Center for Health Statistics (NCHS).
Separate control totals were developed for the "65 and older" and "under 65"
civilian noninstitutionalized populations. The sum of the person-level weights
across all persons assigned a positive person level weight is 284,247,327.
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3.2.4 Coverage
The target population for MEPS in this file is the 2001 U.S. civilian
noninstitutionalized population. However, the MEPS sampled households are a
subsample of the NHIS households interviewed in 1999 (Panel 5) and 2000 (Panel
6). New households created after the NHIS interviews for the respective Panels
and consisting exclusively of persons who entered the target population after
1999 (Panel 5) or after 2000 (Panel 6) are not covered by MEPS. Neither are
previously out-of-scope persons who join an existing household but are unrelated
to the current household residents. Persons not covered by a given MEPS panel
thus include some members of the following groups: immigrants; persons leaving
the military; U.S. citizens returning from residence in another country; and
persons leaving institutions. The set of uncovered persons constitutes only a
small segment of the MEPS target population.
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4.0 Strategies for Estimation
This file is constructed for efficient estimation of utilization,
expenditures, and sources of payment for hospital emergency room visits and to
allow for estimates of the number of persons with emergency room visits for
2001.
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4.1 Variables with Missing Values
It is essential that the analyst examine all variables for the presence of
negative values used to represent missing values. For continuous or discrete
variables, where means or totals may be taken, it may be necessary to set minus
values to values appropriate to the analytic needs. That is, the analyst should
either impute a value or set the value to one that will be interpreted as
missing by the computing language used. For categorical and dichotomous
variables, the analyst may want to consider whether to recode or impute a value
for cases with negative values or whether to exclude or include such cases in
the numerator and/or denominator when calculating proportions.
Methodologies used for the editing/imputation of expenditure variables (e.g.,
sources of payment, flat fee, hospital/ER, and zero expenditures) are described
in Section 2.6.6.2.
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4.2 Basic Estimates of Utilization,
Expenditures and Sources of Payment
While the examples described below illustrate the use of event-level data in
constructing person-level total expenditures, these estimates can also be
derived from the person-level expenditure file unless the characteristic of
interest is event specific.
In order to produce national estimates related to emergency room visits,
expenditures, and sources of payment, the value in each record contributing to
the estimates must be multiplied by the weight (PERWT01F) contained on that
record.
Example 1
For example, the total number of emergency room visits for the civilian
noninstitutionalized population of the U.S. in 2001 is estimated as the sum of
the weight (PERWT01F) across all emergency room visit records. That is,
301 Moved Permanently
301 Moved Permanently
= 55,005,259 |
(1) |
Example 2
Subsetting to records based on characteristics of interest expands the scope
of potential estimates. For example, the estimate for the mean out-of-pocket
payment for emergency
room visits (where the visit has a total
expense greater than 0) should be calculated as the
weighted mean of the facility bill and doctor's bill paid by self/family. That
is,
301 Moved Permanently
301 Moved Permanently
= $61.64 |
(2) |
where Xj = ERFSF01Xj + ERDSF01Xj
and
301 Moved Permanently
301 Moved Permanently
= 49,941,321
for all records with ERXP01Xj > 0.
This gives $61.64 as the estimated mean amount of out-of-pocket payment of
expenditures associated with emergency room visits and 49,941,321 as an estimate
of the total number of such emergency room visits with expenditures. Both of
these estimates are for the civilian noninstitutionalized population of the U.S.
in 2001.
Example 3
Another example would be to estimate the mean proportion of total
expenditures paid by private insurance for emergency room visits with
expenditure. This should be calculated as the weighted mean of the proportion of
total expenditures paid by private insurance at the event level. That is,
301 Moved Permanently
301 Moved Permanently
= 0.4430 |
(3) |
where Yj = (ERFPV01Xj + ERDPV01Xj)/ERXP01Xj
and
301 Moved Permanently
301 Moved Permanently
= 49,941,321
for all emergency room visit records with ERXP01Xj > 0.
This gives 0.4430 as the estimated mean proportion of total expenditures paid
by private insurance for emergency room visits with expenditure for the civilian
noninstitutionalized population of the U.S. in 2001.
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4.3 Estimates of the Number of Persons with
Emergency Room Visit Events
When calculating an estimate of the total number of persons with emergency
room visits, users can use a person-level file or this event file. However, this
event file must be used when the measure of interest is defined at the event
level. For example, to estimate the number of persons in the civilian
noninstitutionalized population of the U.S. with emergency room visits where the
patient sees a doctor, this event file must be used. This would be estimated as
301 Moved Permanently
301 Moved Permanently
across all
unique persons i on this file |
(4) |
where
Wi is the sampling weight (PERWT01F) for
person i
and
Xi = 1 if SEEDOCi = 1 for any emergency room
visit record of person i
= 0 otherwise.
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4.4 Person-Based Ratio Estimates
4.4.1 Person-Based Ratio
Estimates Relative to Persons with Emergency Room Use
This file may be used to derive person-based ratio estimates. However, when
calculating ratio estimates where the denominator is at the person level, care
should be taken to
properly define and estimate the unit of analysis as person-level. For
example, the mean expense for persons with emergency room visits is estimated as
301 Moved Permanently
301 Moved Permanently
across all unique persons i on this file |
(5) |
where
Wi is the sampling weight (PERWT01F) for
person i
and
Zi =
301 Moved Permanently
301 Moved Permanently
ERXP01Xi
across all emergency room visits for person i.
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4.4.2 Person-Based Ratio
Estimates Relative to the Entire Population
If the ratio relates to the entire population, this file cannot be used to
calculate the denominator, as only those persons with at least one emergency
room visit are represented on this data file. In this case, the Full Year
Consolidated File, which has data for all sampled persons, must be used to
estimate the total number of persons (i.e., those with use and those without
use). For example, to estimate the proportion of the civilian
noninstitutionalized population of the U.S. with at least one emergency room
visit where the person saw a doctor, the numerator would be derived from data on
this event file, and the denominator would be derived from data on the
person-level file. That is,
301 Moved Permanently
301 Moved Permanently
across all unique persons i on the person-level file |
(6) |
where
Wi is the sampling weight (PERWT01F) for
person i
and
Zi = 1 if SEEDOCj = 1 for any emergency
room visit of person i
= 0 otherwise.
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4.5 Sampling Weights for Merging Previous
Releases of MEPS Household Data with this Event File
There have been several previous releases of MEPS Household Survey public use
data. Unless a variable name common to several files is provided, the sampling
weights contained on these data files are file-specific. The file-specific
weights reflect minor adjustments to eligibility and response indicators due to
birth, death, or institutionalization among respondents.
For estimates from a MEPS data file that do not require merging with
variables from other MEPS data files, the sampling weight(s) provided on that
data file are the appropriate weight(s). When merging a MEPS Household data file
to another, the major analytical variable (i.e., the dependent variable)
determines the correct sampling weight to use.
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4.6 Variance Estimation (VARSTR01, VARPSU01)
To obtain estimates of variability (such as the standard error of sample
estimates or corresponding confidence intervals) for estimates based on MEPS
survey data, one needs to take into account the complex sample design of MEPS.
Various approaches can be used to develop such estimates of variance including
use of the Taylor Series or various replication methodologies. Replicate weights
have not been developed for the MEPS 2001 data. Variables needed to implement a
Taylor Series estimation approach are provided in the file and are described in
the paragraph below. Using a Taylor Series approach, variance estimation strata
and the variance estimation PSUs within these strata must be specified. The
corresponding variables on the MEPS full year utilization database are VARSTR01
and VARPSU01, respectively. Specifying a "with replacement" design in a computer
software package such as SUDAAN (Shah, 1996) should provide standard errors
appropriate for assessing the variability of MEPS survey estimates. It should be
noted that the number of degrees of freedom associated with estimates of
variability indicated by such a package may not appropriately reflect the actual
number available. For MEPS sample estimates for characteristics generally
distributed throughout the country (and thus the sample PSUs), there are over
100 degrees of freedom associated with the corresponding estimates of variance.
The following illustrates these concepts using two examples from Section 4.2.
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Examples 2 and 3 from Section 4.2
Using a Taylor Series approach, specifying VARSTR01 and VARPSU01 as the
variance estimation strata and PSUs (within these strata) respectively and
specifying a "with replacement" design in a computer software package (i.e.,
SUDAAN) will yield standard error estimates of $3.22 and 0.0108 for the
estimated mean of out-of-pocket payment and the estimated mean proportion of
total expenditures paid by private insurance respectively.
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5.0 Merging/Linking MEPS Data Files
Data from the 2011 Emergency Room Visits File can be used alone or in
conjunction with other files. This section provides instructions for linking the
emergency room visits file with other MEPS public use files, namely, the
person-level file, the prescribed medicines file, and the conditions file.
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5.1 Merging a 2001 Person-Level File to the
2001 Emergency Room Visit File
Merging characteristics of interest from person-level file (e.g., MEPS 2001
Full Year Population Characteristics File, or MEPS 2001 Person Level Use and
Expenditure File) expands the scope of potential estimates. To estimate the
total number of emergency room visits for persons with specific demographic
characteristics (e.g., age, race, and sex), population characteristics from a
person-level file need to be merged onto the emergency room visit file. This
procedure is illustrated below. The MEPS 2001 Appendix File, HC-059I, provides
additional detail on how to merge MEPS data files.
- Create data set PERSX by sorting the MEPS 2001 Full Year Population
Characteristics File by the person identifier, DUPERSID. Keep only
variables to be merged onto the emergency room visit file and DUPERSID.
- Create data set EROM by sorting the emergency room visit file by person
identifier, DUPERSID.
- Create final data set NEWEROM by merging these two files by DUPERSID,
keeping only records on the emergency room visit file.
The following is an example of SAS code which completes these steps:
PROC SORT DATA=2001 Full Year Population Characteristics File
(KEEP= DUPERSID AGE31X AGE42X AGE53X SEX RACEX EDUCYR) OUT=PERSX;
BY DUPERSID;
RUN;
PROC SORT DATA=EROM;
BY DUPERSID;
RUN;
DATA NEWEROM;
MERGE EROM (IN=A) PERSX(IN=B);
BY DUPERSID;
IF A;
RUN;
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5.2 Linking the 2001 Emergency Room Visits File to the 2001 Medical
Conditions File and/or the 2001 Prescribed Medicines File
Due to survey design issues, data users/analysts must keep limitations and
caveats in mind when linking the different files. Those limitations/caveats are
listed below. For detailed linking examples, including SAS code, data
users/analysts should refer to the MEPS 2001 Appendix File, HC-059I.
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5.2.1 Limitations/Caveats of
RXLK (the Prescribed Medicine Link File)
The RXLK file provides a link from the MEPS event files to the 2001
Prescribed Medicine File. When using RXLK, data users/analysts should keep in
mind that one emergency room visit can link to more than one prescribed medicine
record. Conversely, a prescribed medicine event may link to more than one
emergency room visit or different types of events. When this occurs, it is up to
the data user/analyst to determine how the prescribed medicine expenditures
should be allocated among those medical events.
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5.2.2
Limitations/Caveats of CLNK (the Medical Conditions Link File)
The CLNK provides a link from MEPS event files to the 2001 Medical Conditions
File. When using the CLNK, data users/analysts should keep in mind that (1)
conditions are self-reported and (2) there may be multiple conditions associated
with an emergency room visit. Data users/analysts should also note that not all
emergency room visits link to the medical conditions file.
Return To Table Of Contents
References
Cohen, S.B. (1998). Sample Design of the 1996 Medical Expenditure Panel
Survey Medical Provider Component. Journal of Economic Social Measurement.
Vol. 24, 25-53.
Cohen, S.B. (1997). Sample Design of the 1996 Medical Expenditure Panel
Survey Household Component. Rockville (MD): Agency for Health Care Policy and
Research; 1997. MEPS Methodology Report, No. 2. AHCPR Pub. No.
97-0027.
Cohen, J.W. (1997). Design and Methods of the Medical Expenditure Panel
Survey Household Component. Rockville (MD): Agency for Health Care Policy and
Research; 1997. MEPS Methodology Report, No. 1. AHCPR Pub. No.
97-0026.
Cohen, S.B. (1996). The Redesign of the Medical Expenditure Panel Survey: A
Component of the DHHS Survey Integration Plan. Proceedings of the COPAFS
Seminar on Statistical Methodology in the Public Service.
Cox, B.G. and Cohen, S.B. (1985). Chapter 6: A Comparison of Household and
Provider Reports of Medical Conditions. In Methodological Issues for Health
Care Surveys. Marcel Dekker, New York.
Cox, B. and Iachan, R. (1987). A Comparison of Household and Provider Reports
of Medical Conditions. Journal of Economic and Social Measurement.
82(400):1013-18.
Edwards, W.S., Winn, D.M., Kurlantzick V., et al. (1994). Evaluation of
National Health Interview Survey Diagnostic Reporting. National Center for
Health Statistics, Vital Health 2(120).
Elixhauser A., Steiner C.A., Whittington C.A., and McCarthy E. Clinical
Classifications for Health Policy Research: Hospital Inpatient Statistics, 1995.
Healthcare Cost and Utilization Project, HCUP-3 Research Note. Rockville, MD:
Agency for Health Care Policy and Research; 1998. AHCPR Pub. No. 98-0049.
Health Care Financing Administration (1980). International Classification of
Diseases, 9th Revision, Clinical Modification (ICD-CM). Vol. 1. (DHHS
Pub. No. (PHS) 80-1260). DHHS: U.S. Public Health Services.
Johnson, A.E. and Sanchez, M.E. (1993). Household and Medical Provider
Reports on Medical Conditions: National Medical Expenditure Survey, 1987. Journal of Economic and Social Measurement. Vol. 19, 199-233.
Monheit, A.C., Wilson, R., and Arnett, III, R.H. (Editors). Informing
American Health Care Policy. (1999). Jossey-Bass Inc., San Francisco.
Shah, B.V., Barnwell, B.G., Bieler, G.S., Boyle, K.E., Folsom, R.E., Lavange,
L., Wheeless, S.C., and Williams, R. (1996). Technical Manual: Statistical
Methods and Algorithms Used in SUDAAN Release 7.0, Research Triangle Park,
NC: Research Triangle Institute.
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D. Variable-Source Crosswalk
VARIABLE-SOURCE CROSSWALK
FOR MEPS HC-059E: 2001 EMERGENCY ROOM VISITS
Survey Administration Variables
Variable |
Description |
Source |
DUID |
Dwelling unit ID |
Assigned in sampling |
PID |
Person number |
Assigned in sampling |
DUPERSID |
Person ID (DUID+PID) |
Assigned in sampling |
EVNTIDX |
Event ID |
Assigned in sampling |
EVENTRN |
Event round number |
CAPI derived |
ERHEVIDX |
Event ID for corresponding hospital stay |
Constructed |
FFEEIDX |
Flat fee ID |
CAPI derived |
MPCDATA |
MPC data flag |
Constructed |
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Emergency Room Visit Event Variables
Variable |
Description |
Source |
ERDATEYR |
Event date - year |
CAPI derived |
ERDATEMM |
Event date - month |
CAPI derived |
ERDATEDD |
Event date - day |
CAPI derived |
SEEDOC |
Did person talk to MD this visit |
ER01 |
VSTCTGRY |
Best category for care person receive on visit date |
ER02 |
VSTRELCN |
Was this visit related to spec hlth cond |
ER03 |
LABTEST |
This visit did person have lab tests |
ER05 |
SONOGRAM |
This visit did person have sonogram or ultrasound |
ER05 |
XRAYS |
This visit did person have x-rays |
ER05 |
MAMMOG |
This visit did person have a mammogram |
ER05 |
MRI |
This visit did person have an MRI/Catscan |
ER05 |
EKG |
This visit did person have an EKG or ECG |
ER05 |
EEG |
This visit did person have an EEG |
ER05 |
RCVVAC |
This visit did person receive a vaccination |
ER05 |
ANESTH |
This visit did person receive anesthesia |
ER05 |
OTHSVCE |
This visit did person have other diagnostic tests or exams |
ER05 |
SURGPROC |
Was a surgical procedure performed on person this visit |
ER06 |
MEDPRESC |
Any medicine prescribed for person this visit |
ER08 |
VAPLACE |
VA facility flag |
Constructed |
ERICD1X |
3-digit ICD-9-CM condition code |
Edited |
ERICD2X |
3-digit ICD-9-CM condition code |
Edited |
ERICD3X |
3-digit ICD-9-CM condition code |
Edited |
ERPRO1X |
2-digit ICD-9-CM procedure code |
Edited |
ERCCC1X |
Modified Clinical Classification Code |
Constructed/Edited |
ERCCC2X |
Modified Clinical Classification Code |
Constructed/Edited |
ERCCC3X |
Modified Clinical Classification Code |
Constructed/Edited |
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Flat Fee Variables
Variable |
Description |
Source |
FFERTYPE |
Flat fee bundle |
Constructed |
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Imputed Total Expenditure Variables
Variable |
Description |
Source |
ERXP01X |
Total expenditure for event (ERFXP01X + ERDXP01X) |
Constructed |
ERTC01X |
Total charge for event (ERFTC01X + ERDTC01X) |
Constructed |
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Imputed Facility Expenditure Variables
Variable |
Description |
Source |
ERFSF01X |
Facility amount paid, family (Imputed) |
CP Section (Edited) |
ERFMR01X |
Facility amount paid, Medicare (Imputed) |
CP Section (Edited) |
ERFMD01X |
Facility amount paid, Medicaid Imputed) |
CP Section (Edited) |
ERFPV01X |
Facility amount paid, private insurance (Imputed) |
CP Section (Edited) |
ERFVA01X |
Facility amount paid, Veterans Administration (Imputed) |
CP Section (Edited) |
ERFTR01X |
Facility amount paid, TRICARE Imputed) |
CP Section (Edited) |
ERFOF01X |
Facility amount paid, other federal (Imputed) |
CP Section (Edited) |
ERFSL01X |
Facility amount paid, state & local government (Imputed) |
CP Section (Edited) |
ERFWC01X |
Facility amount paid, Workers' Compensation (Imputed) |
CP Section (Edited) |
ERFOR01X |
Facility amount paid, other private insurance (Imputed) |
Constructed |
ERFOU01X |
Facility amount paid, other public insurance (Imputed) |
Constructed |
ERFOT01X |
Facility amount paid, other insurance (Imputed) |
CP Section (Edited) |
ERFXP01X |
Facility sum payments ERFSF01X - ERFOT01X |
Constructed |
ERFTC01X |
Total facility charge (Imputed) |
CP Section (Edited) |
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Imputed Physician Expenditure Variables
Variable |
Description |
Source |
ERDSF01X |
Doctor amount paid, family (Imputed) |
Constructed |
ERDMR01X |
Doctor amount paid, Medicare (Imputed) |
Constructed |
ERDMD01X |
Doctor amount paid, Medicaid (Imputed) |
Constructed |
ERDPV01X |
Doctor amount paid, private insurance (Imputed) |
Constructed |
ERDVA01X |
Doctor amount paid, Veterans Administration (Imputed) |
Constructed |
ERDTR01X |
Doctor amount paid, TRICARE (Imputed) |
Constructed |
ERDOF01X |
Doctor amount paid, other federal (Imputed) |
Constructed |
ERDSL01X |
Doctor amount paid, state & local government (Imputed) |
Constructed |
ERDWC01X |
Doctor amount paid, Workers' Comp (Imputed) |
Constructed |
ERDOR01X |
Doctor amount paid, other private insurance (Imputed) |
Constructed |
ERDOU01X |
Doctor amount paid, other public insurance (Imputed) |
Constructed |
ERDOT01X |
Doctor amount paid, other insurance (Imputed) |
Constructed |
ERDXP01X |
Doctor sum payments ERDSF01X - ERDOT01X |
Constructed |
ERDTC01X |
Total doctor charge (Imputed) |
Constructed |
IMPFLAG |
Imputation status |
Constructed |
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Weights
Variable |
Description |
Source |
PERWT01F |
Final person level weight, 2001 |
Constructed |
VARSTR01 |
Variance estimation stratum, 2001 |
Constructed |
VARPSU01 |
Variance estimation PSU, 2001 |
Constructed |
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