MEPS HC-027: 1998 Medical Conditions

Individual identifiers have been removed from the macro-data contained in the files on this CD-ROM. 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-I), 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 it was 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; and

By using this 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 18 U.S.C. 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.

This documentation describes one in a series of public use files from the Medical Expenditure Panel Survey (MEPS). The survey provides a new and extensive data set on the use of health services and health care in the United States.

The Medical Expenditure Panel Survey (MEPS) is conducted to provide nationally representative estimates of health care use, expenditures, sources of payment, and insurance coverage for the U.S. civilian non-institutionalized population. MEPS is cosponsored by the Agency for Healthcare Research and Quality (AHRQ) and the National Center for Health Statistics (NCHS).

MEPS comprises three component surveys: the Household Component (HC), the Medical Provider Component (MPC), and the Insurance Component (IC). The HC is the core survey, and it forms the basis for the MPC sample and part of the IC sample. 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, also known as NMES-1) was conducted in 1977, the National Medical Expenditure Survey (NMES-2) in 1987. Beginning in 1996, MEPS continues 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 system.

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 accommodate these goals, new MEPS design features include linkage with the National Health Interview Survey (NHIS), from which the sampled households for the MEPS HC are drawn, and continuous 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.

The MEPS HC, a nationally representative survey of the U.S. civilian non-institutionalized 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 1/2 year period. Employing computer-assisted personal interviewing (CAPI) technology, data on medical expenditures and use for two calendar years are collected from each household. This series of data collection rounds is launched each 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 sample of households selected for the MEPS HC is drawn from among respondents to the NHIS, conducted by NCHS. The NHIS provides a nationally representative sample of the U.S. civilian non-institutionalized population, with oversampling of Hispanics and blacks.

The MEPS MPC supplements and validates information on medical care events reported in the MEPS HC by obtaining data directly from medical providers and pharmacies identified by household respondents. The MPC sample includes all hospitals, hospital physicians, home health agencies, and pharmacies reported in the HC. Also included in the MPC are office-based physicians:

Data are collected on medical and financial characteristics of medical and pharmacy events reported by HC respondents, including:

The MEPS IC collects data on health insurance plans obtained through employers, unions, and other sources of private health insurance. 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, eligibility requirements, and employer characteristics.

Establishments participating in the MEPS IC are selected through four sampling frames:

To provide an integrated picture of health insurance, data collected from the first sampling frame (employers and insurance providers) are linked back to data provided by the MEPS HC respondents. Data from the other three sampling frames are collected to provide annual national and State estimates of the supply of private health insurance available to American workers and to evaluate policy issues pertaining to health insurance.

The MEPS IC is an annual panel survey. Data are collected from the selected organizations through a prescreening telephone interview, a mailed questionnaire, and a telephone followup for nonrespondents.

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 and microdata files. Summary reports are released as printed documents and electronic files. Microdata files are released on CD-ROM and/or as electronic files. A catalog of all MEPS products released to date is provided on the AHRQ web site (http://www.meps.ahrq.gov/).

Printed documents and CD-ROMs are available through the AHRQ Publications Clearinghouse. Write or call:

Be sure to specify the AHRQ number of the document or CD-ROM you are requesting. Selected electronic files are available from the Internet on the AHRQ home page: http://www.meps.ahrq.gov/.

Additional information on MEPS is available from the MEPS project manager or the MEPS public use data manager at the Center for Cost and Financing Studies, Agency for Healthcare Research and Quality.

This documentation describes the data contained in MEPS Public Use Release HC-027, which is one in a series of public use data files to be released from 1998 of the Medical Expenditure Panel Survey Household Component (MEPS HC).

Released in ASCII and SAS formats, this public use file provides information on household-reported medical conditions collected on a nationally representative sample of the civilian noninstitutionalized population of the United States for calendar year 1998 MEPS HC.

This file contains 72,576 records. Each record represents one household-reported medical condition reported in the 1998 portion of Round 3, and Rounds 4 and 5 for Panel 2, as well as Rounds 1 and 2 of Panel 3, and the 1998 portion of Round 3 for Panel 3 (i.e., Rounds for MEPS panels covering calendar year 1998).

The following documentation offers a brief overview of the types and levels of data provided, the content and structure of the files. It contains the following sections:

Detailed ICD-9 Condition, Procedure, and Clinical Classification Code Frequencies

A codebook of all the variables included in the 1998 Medical Conditions File is provided in a separate file (H27CB.PDF). The Readme file contains the programming information.

For more information on MEPS survey design see Cohen, 1997; Cohen 1997; and Cohen 1996. A copy of the survey instrument used to collect this information on this file is available on the MEPS web site: http://www.meps.ahrq.gov.

For each variable on the file, both weighted and unweighted frequencies are provided in the codebook. Because the conditions identified in this file are derived from self-reports, these data cannot be used to make estimates of disease, prevalence of health conditions, or mortality/morbidity.

Data from this file can be merged with 1998 MEPS person-level data using DUPERSID to append person-level characteristics such as demographic or health insurance characteristics to each record (see Section 4.0 for details). Data from this file also can be merged to 1998 MEPS Medical Provider Event Files (HC-026A, HC-026B, HC-026D through HC-026H) by using the link files provided on HC-026I, File 1 (see HC-026I for details). Since each record represents a single condition reported by household respondents, some household respondents may have multiple medical conditions and thus will be represented on multiple records on this file. Other household respondents may have reported no medical conditions and thus will have no records on this file.

Unique person identifiers
Unique condition identifiers
Medical condition variables
Weight and variance estimation variables

Generally, -1, -7, -8, and –9 have not been edited on this file. The values of –1 and –9 can be edited by analysts by following the skip patterns in the questionnaire. These reserve codes indicated appropriate responses for skip patterns associated with priority and injury conditions (see HC-018 Sections 2.2 for details.) Priority and injury conditions on the current file did not undergo the extensive editing they did on previous releases of the Medical Conditions file. Data users should note that the reserve codes –11 and –12 are not used on the current file.

This codebook describes an ASCII data set and provides the following programming identifiers for each variable:

In general, variable names reflect the content of the variable, with an 8 character limitation. For questions asked in a specific Round, the end digit in the variable name reflects the Round in which the question was asked. Edited variables end in an "X" and are so noted in the variable label.

Variables contained in this delivery were derived either from the questionnaire itself or from the CAPI. The source of each variable is identified in Appendix 1 entitled "Variable to Source Crosswalk." Sources for each variable are indicated in one of four ways: (1) variables which are derived from CAPI or assigned in sampling are so indicated; (2) variables derived from complex algorithms associated with re-enumeration are labeled "RE Section"; (3) variables which come from one or more specific questions have those numbers and questionnaire section indicated in the "Source" column; (4) variables constructed from multiple questions using complex algorithms are labeled "Constructed" in the "SOURCE" column.

The definitions of Dwelling Units (DU s) and Group Quarters in the MEPS-HC is generally consistent with the definitions employed for the National Health Interview Survey (NHIS). The dwelling unit ID (DUID) is a five-digit random number assigned after the case was sampled for MEPS. The person number (PID) uniquely identifies each person within the dwelling unit. The variable DUPERSID uniquely identifies each person represented on the file, and is the combination of the variables DUID and PID. CONDN indicates the condition number of each condition for an individual respondent (e.g., condition number 1, 2, 3, etc.) plus a control digit. The number of conditions for persons represented on this file ranges from 1 to 53. CONDIDX uniquely identifies each condition (i.e., each record on the file), and is the combination of DUPERSID and CONDN.

PANEL98 is a constructed variable used to specify the panel number for the interview. PANEL98 will indicate either Panel 2 or Panel 3.

CONDRN indicates the round in which the condition was first reported. For a small number of cases, conditions that actually began in an earlier round were not reported by respondents until subsequent rounds of data collection. For these cases no editing was performed to reconcile the round in which a condition began and the round that the condition was first reported.

This file contains variables describing medical conditions reported by respondents in several sections of the MEPS questionnaire, including the Condition Enumeration Section, Health Status Section, and all questionnaire sections collecting information about health provider visits, prescription medications, and disability days (see Variable-Source Crosswalk in Appendix 1 for details).

Certain conditions were a priori designated as "priority conditions" (PRIOLIST=1) due to their prevalence, expense, or relevance to policy. Some were long-term life-threatening conditions, such as cancer, diabetes, emphysema, high cholesterol, HIV/AIDS, hypertension, ischemic heart disease, and stroke. Others were chronic manageable conditions, including arthritis, asthma, gall bladder disease, stomach ulcers, and back problems of any kind. In addition, Alzheimer’s disease or other dementias, as well as depression and anxiety disorders, were included in the priority list. For a complete listing of "priority conditions" see Appendix 4. Priority conditions were identified as such in the field by MEPS interviewers. Occasionally errors were made and not all priority conditions were identified. Consequently, these records are missing the follow-up questions described below. Likewise, some conditions were inaccurately identified as priority conditions. These records do have follow-up questions even though they are not priority conditions.

When a condition was first mentioned, respondents were asked whether it was due to an accident or an injury (INJURY=1). Some injuries are also priority conditions (e.g. back pain).

The date a priority condition bean (CONDBEGD, CONDBEGM, CONDBEGY) is collected only for conditions that appear on the priority list. The date an accident or injury occurred (ACCDENTD, ACCDENTM, ACCDENTY) is collected only for accident/injury conditions. For 44 priority conditions and 27 injuries respondents reported that the year the condition began or the date the accident occurred was 1999. These records were retained on the current file because they link to a 1998 medical provider event.

When a respondent first reported a condition on the priority list (PRIOLIST=1) or a condition caused by an injury (INJURY=1) a series of questions regarding health care utilization for that condition and the effect of that condition on the person’s overall health was asked. The names of these variables end in 1, 2, 3, 4 or 5 indicating the round in which they were asked. The following questions were asked in the round in which the respondent first reported a priority condition or a condition resulting from an injury.

When a respondent reported a condition that resulted from an accident or injury (INJURY=1) the following information was obtained from respondents during the round in which the injury was first reported.

For priority conditions only, additional information was obtained in rounds subsequent to the one in which the condition was first mentioned. This information was obtained only if there was a medical provider visit or a prescribed medication or a disability day associated with the condition in that round. If this occurred, the condition was "selected" for follow-up questions for the round.

For priority conditions selected in rounds after they were first mentioned, the following questions were asked:

For Panel 2, Rounds 1 and 2 occurred in 1997 and are not included on this file unless the condition was identified as a priority condition (see the discussion of PRIOFLG below). For Panel 3, Rounds 4 and 5 occurred in 1999 and are not included on this file. Therefore, round-specific variables for Rounds 1 and 2 of Panel 2 are assigned an inapplicable code (-1) for respondents in Panel 2, and round-specific variables for Rounds 4 and 5 of Panel 3 are assigned an inapplicable code (-1). Data for Rounds 4 and 5 pertain only to Panel 2; data for Rounds 1 and 2 pertain only to Panel 3, and both panels provide data from Round 3. (Note: PANEL98 must be used to identify whether Round 3 variables were collected in Panel 2 or Panel 3.)

All priority conditions and conditions resulting from an injury that were first reported in Rounds 1 or 2 of Panel 2 have round-specific data for those rounds included on the 1997 Medical Conditions File (HC-018). The variables PRIOFLG and INJURFLG indicate if the condition is "Not a priority/injury condition" (0), whether or not "Additional information is included on the 1997 Medical Condition File" (1), or if "all priority/injury information is included on the current file" (2).

Note: Priority conditions are generally chronic conditions. Even though a respondent may not have reported a medical provider visit, a prescribed medicine or a disability in 1998 due to the condition, analysts should consider that the respondent is probably still experiencing the condition. If a Panel 2 respondent reported a priority condition in Rounds 1 or 2 and did not have a provider visit, a prescribed medicine, or a disability day for the condition in Rounds 3, 4 or 5 of Panel 2, round-specific variables for Rounds 3, 4, and 5 are coded as –1. The only information provided on the current 1998 file is the ICD9CODX, ICD9PROX, and CCCODEX. These records also can be identified if PRIOFLG=1.

A set of constructed variables (CRND1 – CRND5) indicate the round in which the condition was first reported, and for subsequent rounds, the round(s) in which a medical provider event, prescription medication, or disability day occurred due to condition. For example, consider a condition for which CRND1 = 0, CRND2 = 1, and CRND3 = 1; this sequence of CRND indicators implies that the condition was not present during Round 1 (CRND1 = 0), was first mentioned during Round 2, and was associated with a medical event during Round 3. These round indicators have not been reconciled with CONDRN. CRND1 – CRND5 are not applicable for most pregnancies, prenatal visits, or deliveries due to the questionnaire design.

This file contains 3 flag variables indicating whether or not a condition is associated with a missed workday (MISSWORK), a missed school day (MISSSCHL), or a bed day (INBEDFLG).

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 1996 ICD-9-CM codes, including medical condition and V codes (see Health Care Financing Administration, 1980), by professional coders. Although codes were verified and error rates did not exceed 2.5 percent for any coder, 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 (see Cox and Cohen, 1985; Cox and Iachan, 1987; Edwards, et al, 1994; and Johnson and Sanchez, 1993).

In order to preserve respondent confidentiality, nearly all of the condition codes provided on this file (ICD9CODX) have been collapsed from fully specified codes to 3-digit code categories. Table 1 in Appendix 2 provides a table of unweighted and weighted frequencies for all ICD-9 condition code values reported on the file. In this table, values that reflect this collapsing have an asterisk in the label indicating that the 3-digit category includes all the subclassifications within that category. For example, the ICD9CODX value of 034 "Strep Throat/Scarlet Fev *" includes the fully-specified subclassifications 034.0 and 034.1; the value 296 "Affective Disorders*" includes the fully specified subclassifications 296.0 through 296.99. Less than 1 percent of the records on this file were edited further by collapsing two or more 3-digit codes into one 3-digit code.

Similarly, most of the procedure codes (ICD9PROX) were collapsed from fully specified codes to 2-digit category codes. Table 2 in Appendix 2 provides unweighted and weighted frequencies for ICD9PROX, and this type of collapsing is identified by an asterisk in the variable label. For example, the ICD9PROX value in 81 "Joint Repair*" includes subclassifications 81.0 through 81.99. Some records were further edited to combine 2 or more 2-digit categories.

Users should note that because of the design of the survey, most deliveries (i.e. births) are coded as pregnancies. For more accurate estimates for deliveries analysts should use RSINHOS "Reason Entered Hospital" found on the Hospital Inpatient Stays Public Use File (HC-026D).

Conditions and procedures were reported in the same sections of the HC questionnaire (see Variable-Source Crosswalk in Appendix 1). Labels for all values of the variables ICD9CODX and ICD9PROX, as shown in Tables 1 and 2, are provided in the SAS programming statements included in this release (see the HC-027SU.TXT file).

ICD-9-CM condition codes have been aggregated into clinically meaningful categories that group similar conditions (CCCODEX). CCODEX was 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 259 mutually exclusive categories, most of which are clinically homogeneous. Appendix 3 lists the ICD-9-CM codes that have been aggregated for each clinical classification category. Note that the reported ICD-9-CM code values were mapped to the appropriate clinical classification category prior to being collapsed to 3-digit ICD-9 codes. For confidentiality purposes a small number (less than 2 percent) of clinical classification codes have been edited. Table 3 in Appendix 2 provides weighted and unweighted frequencies for CCCODEX. Labels for all values of the variable CCCODEX, as shown in Table 3, are provided in the SAS programming statements included in this release (see the H27SU.TXT file).

In Rounds 3 and 5 respondents were asked whether or not alternative care was received for a condition (APCARE53). Alternative care includes the use of treatments such as acupuncture, nutritional advice, massage therapy, herbal remedies, bio-feedback, imagery or relaxation techniques, homeopathic treatments, spiritual healing or prayer, hypnosis, or traditional medicine such as Chinese or American Indian medicine. APCARE3 has three possible values: "0" if the person received no alternative care for any condition , "1" if alternative care was received for this condition, and "2" if alternative care was not received for this condition, but was received for another condition on the file.

The variables are OBNUM, OPNUM, HHNUM, DNNUM, HSNUM, ERNUM, and RXNUM indicate the total number of 1998 medical provider events that can be linked to each condition record on the current file for each event type, i.e., office-based, outpatient, home health, dental, hospital stays, emergency room visits, and prescribed medicines, respectively.

These counts of events were derived from Medical Provider Event Public Use Files (HC-026A, HC-026B and HC-026D - HC-026H). Medical provider events associated with conditions include all utilization that occurred between January 1, 1998 and December 31, 1998.

Because persons can be seen for more than one condition per visit, these frequencies will not match the person- or event-level utilization counts. For example, if a person had one hospital stay and was treated for a fractured hip and a fractured shoulder and a concussion, each of these conditions has a unique record and HSNUM=1 for each record. If you sum HSNUM for these records, then the total hospital stays would be 3 when actually there was only 1 hospital stay for that person and 3 conditions were treated. These variables are useful if you wanted to know the number of hospitals for head injuries, hip fractures, etc.

The MEPS is designed to produce estimates at the national and regional level over time for the civilian, noninstitutionalized population of the United States and some subpopulations of interest. The data in this public use set pertain to calendar year 1998. The data were collected in Rounds 1, 2, and 3 for MEPS Panel 3 and Rounds 3, 4, and 5 for MEPS Panel 2. Note that Round 3 for a MEPS panel overlaps two calendar years. The reference period for Round 3 of Panel 2 covers the end of 1997 and the beginning of 1998 while the reference period for Round 3 of MEPS Panel 3 covers the end of 1998 and the beginning of 1999. As discussed earlier, for Panel 3, about 30 percent of the Round 2 RUs had reference periods that extended into 1999, but this will present no problems analytically. All the usual information is presented in the standard variables. The only utilization data that appear on the file are those associated with health care events occurring in calendar year 1998, and all utilization data for 1998 reported by MEPS respondents have been included in this database.

The households in this 1998 MEPS database are related to households participating in the National Health Interview Survey in 1996 and 1997. The households (occupied dwelling units) selected for MEPS Panel 2 were a subsample of 1996 NHIS respondents while those in MEPS Panel 3 were a subsample of 1997 NHIS respondents. A household may contain one or more family units, each consisting of one or more individuals. Analysis can be undertaken using either the individual or the family as the unit of analysis.

For MEPS Panel 2 several domains of interest were oversampled to provide increased precision for analytic purposes. These domains included households containing persons with one of the following characteristics based on NHIS data: adults with functional impairments, children with limitations in activity, individuals aged 18-64 with expected high medical expenditures, individuals with family incomes expected to be below 200% of the poverty level in 1997, and adults with other impairments. Because some households could be associated with more than one domain, a hierarchical sample selection procedure was employed. If a household could be associated with multiple domains, it was assigned to the domain given the highest priority in the hierarchy.

There have been some published reports on the MEPS sample design. For detailed information on the MEPS sample design for Panel 1, see Cohen, S. 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. For detailed information on the MEPS sample design for Panel 2, see Appendix 2: Cohen, S., Sample Design of the 1997 Medical Expenditure Panel Survey Household Component.

The sample of 6,300 households (occupied dwelling units) for the MEPS Panel 2 consisted of a nationally representative subsample of the households responding to the 1996 National Health Interview Survey (NHIS). A subsample of 5,166 households was selected for MEPS Panel 3 from among households responding to the 1997 NHIS.

The NHIS sample design has three stages of sample selection: an area sample of PSUs; a sample of segments (single or groups of blocks or block equivalents) within sampled PSUs; and a sample of housing units within segments. Among initially sampled households, those containing Hispanics and blacks were oversampled at rates of approximately 2 and 1.5 times the rate of remaining households. These same rates of oversampling are reflected in the MEPS sample of households. The only major difference in the definition of a household between NHIS and MEPS is that college aged students living away from home during the school year were interviewed at their place of residence for the NHIS but were identified by and linked to their parents’ household for MEPS.

In the database "MEPS HC-028: 1998 Full Year Population Characteristics," weight variables are provided for estimation purposes. Procedures and considerations associated with the construction and interpretation of person and family-level estimates using these and other variables are discussed below.

In order to produce annual health care estimates for calendar year 1998 based on the full MEPS sample, data will also need to be pooled across the second and third MEPS national samples. More specifically, full calendar year 1998 data collected in Rounds 3 through 5 for the MEPS Panel 2 sample are pooled with data from the first three rounds of data collection for the MEPS Panel 3 sample (the general approach is illustrated below—the anomaly of having the reference periods of some RUs in Panel 3, Round 2 extend into 1999 has been ignored here for purposes of clarity). Overall, the full 1998 MEPS household sample consists of approximately 9,023 reporting units (where student Rus are linked to parent RUs for this count) which include 22,953 individuals that completed the full series of MEPS interviews for their entire period of eligibility, providing the necessary information to produce national use estimates for calendar year 1998.

Conditioned on response to Rounds 1-3 of the Panel 2 MEPS, of 13,067 key and inscope individuals eligible for data collection in 1998, 12,260 (93.82 percent) provided data for their entire period of eligibility. Consequently, after factoring in the impact of survey attrition, the overall Panel 2 MEPS person-level response rate for deriving annual estimates was 64.95 percent (.6923 x .9382). Of these full year respondents for calendar year 1998, 12,086 were in scope on December 31, 1998.

Conditioned on response to Round 1 of the Panel 3 MEPS, of 11,379 key and inscope individuals eligible for data collection in 1998, 10,693 (93.97 percent) provided data for their entire period of eligibility. Consequently, after factoring in the impact of survey attrition, the overall Panel 3 MEPS person-level response rate for deriving annual estimates was 70.76 percent (.753 x .9397). Of these full year respondents for calendar year 1998, 10,544 were in scope on December 31, 1998.

A pooled response rate for the survey respondents in this data set can be obtained by taking an average of the panel-specific response rates. This pooled response rate for the combined panels is 67.9 percent, consisting of a total of 22,953 survey participants.

There is a single person-level weight variable called WTDPER98. However, care should be taken in its application as it permits both "point-in-time" and "range of time" estimates, depending on the variables used to define the set of persons of interest for analysis. A person-level weight was assigned to each key, inscope person who responded to MEPS for the full period of time that he or she was inscope during the MEPS. For Panel 3 this requirement pertained only to 1998, but for Panel 2 it pertained to both 1997 and 1998. (Recall that a person is inscope whenever he or she is a member of the civilian, noninstitutionalized portion of the U.S. population.)

The data in this file can be used to develop estimates on persons in the civilian, noninstitutionalized population on December 31, 1998 and for the slightly larger population of persons in the civilian, noninstitutionalized population at any time during 1998. To obtain a cross-sectional (point-in-time) estimate for all inscope persons living in the country on December 31, 1998, include cases with both WTDPER98>0 (a positive person-level weight) and INSC1231=1 (the person is inscope on December 31, 1998). To obtain an estimate for all persons who were inscope at some time in 1998, include all cases with WTDPER98>0. After selecting the appropriate cases, apply the weight variable WTDPER98 to the analytic variable(s) of interest to obtain national estimates. The following table contains a summary of cases to include and sample sizes for these two populations (for shorthand purposes, the term "general" is used to indicate the "civilian, noninstitutionalized" component of the U.S. population).

The person-level weight WTDPER98 was developed in three stages. A person-level weight for Panel 3 was created, including both an adjustment for nonresponse over time and poststratification, controlling to Current Population Survey (CPS) population estimates based on five different variables. Poverty status was not included since income data for assigning persons to a poverty status was yet to be established. Then a person-level weight for Panel 2 was created, again including an adjustment for nonresponse over time and poststratification, controlling to CPS population estimates based on the same five variables. When poverty status information derived from income variables became available, a 1998 average annual weight was formed from the Panel 2 and Panel 3 weights by multiplying the Panel weights by .5. Then a final poststratification was done on this composite weight variable, including poverty status as well as the original five poststratification variables in the establishment of the final 1998 person level weight.

The person-level weight for MEPS Panel 2 was developed using the 1997 full year weight for an individual as a "base" weight for survey participants present in 1997. For key, inscope respondents who joined an RU some time in 1998 after being out-of-scope in 1997, the "base" weight was taken to be the 1997 family weight associated with the family the person joined. The weighting process included an adjustment for nonresponse over Rounds 4 and 5 as well as poststratification to population control totals from the CPS for December, 1998. These control totals were derived by scaling back the population distribution obtained from the March 1999 CPS to reflect the December, 1998 CPS estimated population distribution, employing age and sex data available from the December, 1998 CPS. 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, 1998 is 273,007,600. Key, responding persons not inscope on December 31, 1998 but inscope earlier in the year retained, as their final Panel 2 weight, the weight after the nonresponse adjustment.

The person-level weight for MEPS Panel 3 was developed using the MEPS Round 1 person-level weight as a "base" weight. For key, inscope 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 the remaining data collection rounds in 1998 as well as poststratification to the same population control figures for December 1998 used for the MEPS Panel 2 weights. The same five variables employed for Panel 2 poststratification (census region, MSA status, race/ethnicity, sex, and age) were used for Panel 3 poststratification. As with Panel 2, Panel 3 key, responding persons not inscope on December 31, 1998 but inscope earlier in the year retained the weight after the nonresponse adjustment as their final Panel 3 weight.

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; the probability of selection of dwelling units associated with the oversampling of five population domains of analytic interest (for Panel 2 only); 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 1998 CPS data base. The five oversampled domains for Panel 2 were households with: persons with functional impairments; children with limitations in activity; individuals 18-64 expected to incur high medical expenditures based on a statistical model; persons with family incomes expected to be below 200 percent of poverty, based on a statistical model; and adults with other impairments.

Variables used in the establishment of person-level poststratification control totals 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 for December 31, 1998 is 270,114,457 (WTDPER98>0 and INSC1231=1). The inclusion of key, inscope persons who were not inscope on December 31, 1998 brings the estimated total number of persons represented by the MEPS respondents over the course of the year to 273,229,527 (WTDPER98>0). The weighting process included poststratification to population totals obtained from the 1996 MEPS Nursing Home Component for the number of individuals admitted to nursing homes.

The target population for MEPS is the 1998 U.S. civilian, noninstitutionalized population. However, the MEPS sampled households are a subsample of the NHIS households interviewed in 1996 (Panel 2) and 1997 (Panel 3). New households created after the NHIS interviews for the respective Panels and consisting exclusively of persons who entered the target population after 1996 (Panel 2) or after 1997 (Panel 3) are not covered by MEPS. Neither are persons who join an existing household but are unrelated to the current household residents. Persons not covered by a given MEPS panel thus include those in the following groups who do not join a member of the civilian non-institutionalized population at the time of the corresponding NHIS survey: immigrants; persons leaving the military; U.S. citizens returning from residence in another country; and persons leaving institutions. It should be noted that this set of uncovered persons constitutes just a small proportion of the MEPS target population.

To obtain estimates of variability (such as the standard error of sample estimates or corresponding confidence intervals) for estimates based on MEPS survey data, the complex sample design of MEPS for both person and family-level analyses must be taken into account. Various approaches can be used to develop such estimates of variance including use of the Taylor series or replication methodologies. Replicate weights have not been developed for the MEPS 1998 data.

Using a Taylor Series approach, variance estimation strata and the variance estimation PSUs within these strata must be specified. The corresponding variables on the 1998 MEPS full year utilization database are VARSTR98 and VARPSU98, respectively. Specifying a "with replacement" design in a computer software package, such as SUDAAN, 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 for the 1998 full year data associated with the corresponding estimates of variance.

Data from the current file can be used alone or in conjunction with other files. Merging characteristics of interest from person-level files expands the scope of potential estimates. See HC-026I for instructions on merging the condition file to the Medical Event Files. Person-level characteristics can be merged to the condition file using the following procedure:

Cohen, S. B. (1997). A Sample Design of the 1996 Medical Expenditure Panel Survey Household Component, Rockville (MD): Agency for Healthcare Research and Quality; 1997. MEPS Methodology Report, No. 2. AHCPR Pub. No. 97-0027.

Cohen, J. W. (1997). A Design and Methods of the Medical Expenditure Panel Survey Household Component. Rockville (MD): Agency for Healthcare Research and Quality; 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. and Iachan, R. (1987). A Comparison of Household and Provider Reports of Medical Conditions. Journal of the American Statistical Association 82(400):1013-18.

Edwards, W. S., Winn, D. M., Kurlantzick, V., et al. Evaluation of National Health Interview Survey Diagnostic Reporting. National Center for Health Statistics, Vital Health 2(120). 1994.

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 Healthcare Research and Quality; 1998. AHCPR Pub. No. 98-0049.

Health Care Financing Administration (1980). International Classification of Diseases, 9^th Revision, Clinical Modification (ICD-CM). Vol. 1. (DHHS Pub. No (PHS) 80-1260). DHHS: U.S. Public Health Services.

Shah, B. V., B. G. Barnwell, G. S. Bieler, K. E. Boyle, R. E. Folsom, L. Lavange, S. C. Wheeless, and R. Williams (1996). Technical Manual: Statistical Methods and Algorithms Used in SUDAAN Release 7.0, Research Triangle Park, NC: Research Triangle Institute.

VARIABLE	LABEL	SOURCE
PRIOLIST	Is Condition On Priority List	CN02
CONDBEGD	Date Condition Started --Day	CN05
CONDBEGM	Date Condition Started BMonth	CN05
CONDBEGY	Date Condition Started --Year	CN05
SEEDREV1	RD1: Ever See/Talk to Dr. About Condition	CN03, CN07
SEEDREV2	RD2: Ever See/Talk to Dr. About Condition	CN03, CN07
SEEDREV3	RD3: Ever See/Talk to Dr. About Condition	CN03, CN07
SEEDREV4	RD4: Ever See/Talk to Dr. About Condition	CN03, CN07
SEEDREV5	RD5: Ever See/Talk to Dr. About Condition	CN03, CN07
LSTSAW1	RD1: When Was Last Time Dr. Was Seen	CN04 (Edited)
STILTR1	RD1: Is Person Still Treated For Condition	CN11, CN18 (Edited)
STILTR2	RD2: Is Person Still Treated For Condition	CN11, CN18 (Edited)
STILTR3	RD3: Is Person Still Treated For Condition	CN11, CN18 (Edited)
STILTR4	RD4: Is Person Still Treated For Condition	CN11, CN18 (Edited)
STILTR5	RD5: Is Person Still Treated For Condition	CN11, CN18 (Edited)
OVRALL1	RD1: How Did Condition Affect Overall Health	CN13, CN19 (Edited)
OVRALL2	RD2: How Did Condition Affect Overall Health	CN13, CN19 (Edited)
OVRALL3	RD3: How Did Condition Affect Overall Health	CN13, CN19 (Edited)
OVRALL4	RD4: How Did Condition Affect Overall Health	CN13, CN19 (Edited)
OVRALL5	RD5: How Did Condition Affect Overall Health	CN13, CN19 (Edited)
WHOTYP1	RD1: Who Reported Condition Affect	CN13OV, CN19OV (Edited)
WHOTYP2	RD2: Who Reported Condition Affect	CN13OV, CN19OV (Edited)
WHOTYP3	RD3: Who Reported Condition Affect	CN13OV, CN19OV (Edited)
WHOTYP4	RD4: Who Reported Condition Affect	CN13OV, CN19OV (Edited)
WHOTYP5	RD5: Who Reported Condition Affect	CN13OV, CN19OV (Edited)
FURTCA1	RD1: Was Further Treatment Recommended	CN14 (Edited)
FURTCA2	RD2: Was Further Treatment Recommended	CN14 (Edited)
FURTCA3	RD3: Was Further Treatment Recommended	CN14 (Edited)
FURTCA4	RD4: Was Further Treatment Recommended	CN14 (Edited)
FURTCA5	RD5: Was Further Treatment Recommended	CN14 (Edited)
FOLOCA1	RD1: Receive Follow-Up Care for Condition	CN15 (Edited)
FOLOCA2	RD2: Receive Follow-Up Care for Condition	CN15 (Edited)
FOLOCA3	RD3: Receive Follow-Up Care for Condition	CN15 (Edited)
FOLOCA4	RD4:Receive Follow-Up Care for Condition	CN15 (Edited)
FOLOCA5	RD5:Receive Follow-Up Care for Condition	CN15 (Edited)
SEEDREF1	RD1: Saw Doctor in Reference Period	CN17
SEEDREF2	RD2: Saw Doctor in Reference Period	CN17
SEEDREF3	RD3: Saw Doctor in Reference Period	CN17
SEEDREF4	RD4: Saw Doctor in Reference Period	CN17
SEEDREF5	RD5: Saw Doctor in Reference Period	CN17
CRND1	RD 1: Has Condition Round Information	Constructed
CRND2	RD 2: Has Condition Round Information	Constructed
CRND3	RD 3: Has Condition Round Information	Constructed
CRND4	RD 4: Has Condition Round Information	Constructed
CRND5	RD 5: Has Condition Round Information	Constructed
PRIORFLG	Location of Round Specific Priority Information	Constructed
INJURY	Was Condition Due To Accident/Injury	CN02
ACCDENTD	Date Of Accident -- Day	CN06
ACCDENTM	Date Of Accident B Month	CN06
ACCDENTY	Date Of Accident B Year	CN06
ACCDNWRK	Did Accident Occur At Work	CN07
ACDNTLOC	Where Did Accident Happen	CN08
INOUTHH	Was Accident inside/Outside House	CN09
VEHICLE	Was A Motor Vehicle Involved	CN10
GUN	Was A Gun Involved	CN10
WEAPON	Was Some Other Weapon Involved	CN10
POISON	Was Poison/Poisonous Substance Involved	CN10
FIREBURN	Was Fire/Burning Involved	CN10
DROWN	Was Drowning/Near Drowning Involved	CN10
SPORTS	Was It A Sports Injury	CN10
FALL	Was It A Fall	CN10
ACDNTOTH	Was Something Else Involved	CN10
RECOVER	Fully Recovered From Condition	CN12
INJURFLG	1 = Initial Injury Information on 1997 File
MISSWORK	Flag Associated With Missed Work days	DD04
MISSSCHL	Flag Associated With Missed School Days	DD08
INBEDFLG	Flag Associated With Bed Days	DD12
ICD9CODX	ICD-9 Code for Condition	CE05, HS03, ER04, OP09, MV09, DN02, HH05, PM09 (Edited)
ICD9PROX	ICD-9 Code for Procedure	CE05, HS03, ER04, OP09, MV09, DN02, HH05, PM09 (Edited)
CCCODEX	Clinical Classification Code	Constructed/Edited
APCARE53	Was Alternative Caregiver Consulted	Constructed
HHNUM	# Home Health Events Assoc. w/ Condition	Constructed
DNNUM	# Dental Events Assoc. w/ Condition	Constructed
HSNUM	# Hospital Stays Assoc. w/ Condition	Constructed
OPNUM	# Out-Patient Events Assoc. w/ Condition	Constructed
OBNUM	# Office-Based Events Assoc. w/ Condition	Constructed
ERNUM	# ER Assoc. w/ Condition	Constructed
RXNUM	# Prescribed Medicines Associations W/ Condition	Constructed

Cancer (of any body part)
cancer
tumor
malignancy
malignant tumor
carcinoma
sarcoma
lymphoma
Hodgkin's disease
leukemia
melanoma
metastasis
neuroma
adenoma

Diabetes
diabetes
diabetes mellitus
high blood sugar
juvenile diabetes
(Type I diabetes)
adult-onset diabetes
(Type II diabetes)
diabetic neuropathy

Emphysema
emphysema
chronic obstructive pulmonary
disease (COPD)
chronic bronchitis (MUST use the word 'chronic', only for adults)
Chonic obstructive bronchitis (MUST use the word 'chronic', only for adults)
smokers cough

High Cholesterol
high cholesterol
high or elevated triglycerides
hyperlipidemia
hypercholesterolemia

Ischemic Heart Disease
ischemic heart disease (MUST use the word 'ischemic')
angina
angina pectoris
coronary artery disease
blocked, obstructed, or occluded
coronary arteries
arteriosclerosis
myocardial infarction
heart attack

Stroke
stroke
cerebral hemorrhage
cerebral aneurysm
transient ischemic accident
transient ischemic attack
apoplexy
carotid artery blockage
arterial thrombosis in brain
blood clot in brain

Arthritis
anything with the word 'arthritis'
rheumatoid arthritis
degenerative arthritis
osteoarthritis
bursitis
rheumatism

Gall Bladder Disease
gall bladder disease, trouble, attacks, infection, or problems gallstones

Stomach Ulcers
stomach ulcer
duodenal ulcer
peptic ulcer
bleeding ulcer
ulcerated stomach
perforated ulcer

Back Problems of Any Kind
back problems or pain of any kind (lower or upper back)
sore, hurt, injured, or stiff back
backache
anything with the words 'vertebra', 'vertebrae', 'lumbar', 'spine', or 'spinal'
strained or pulled muscle in back
sprained back
muscle spasms
back spasms
bad back
lumbago
sciatica or sciatic nerve problems
disc problems: herniated, ruptured, slipped, compressed, extruded, dislocated, deteriorated, or misaligned discs

Alzheimer's Disease and Other Dementias
anything with the words 'Alzheimer's' or 'dementia'
organic brain syndrome

Depression and Anxiety Disorders
depression (including severe, chronic, or major depression)
dysthymia
dysthymic disorder
bipolar disorder
manic depression or manic depressive illness
anxiety attacks
panic attacks
anxiety
nerves
nervous condition
nervous breakdown

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