1 National Center for Health Statistics Record Linkage Program Christine S. Cox, Chief, Special...

1

National Center for Health National Center for Health StatisticsStatistics

Record Linkage ProgramRecord Linkage ProgramChristine S. Cox,

Chief, Special Projects Branch (SPB) Office of Analysis & Epidemiology (OAE)

NCHS Data Users ConferenceAugust 12, 2008

U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICESCenters for Disease Control and PreventionNational Center for Health Statistics

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OverviewOverview

NCHS Record Linkage ProgramNCHS Record Linkage Program

Analytic Issues & ToolsAnalytic Issues & Tools

Comparative Analysis of Public vs Comparative Analysis of Public vs Restricted Linked Mortality FilesRestricted Linked Mortality Files

Accessing the Restricted-use Linked Accessing the Restricted-use Linked DataData

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NCHS Record Linkage NCHS Record Linkage ProgramProgram

Links survey data with data collected Links survey data with data collected from administrative recordsfrom administrative records

Designed to maximize the scientific Designed to maximize the scientific value of the NCHS population-based value of the NCHS population-based surveys surveys

Examine factors that influence chronic Examine factors that influence chronic disease, disability, health care disease, disability, health care utilization, morbidity, and mortalityutilization, morbidity, and mortality

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Why Do Linkage?Why Do Linkage?

Augments available information for major Augments available information for major diseases, risk factors, and health service diseases, risk factors, and health service utilizationutilization Links exposures to outcomesLinks exposures to outcomes Provides longitudinal component to survey dataProvides longitudinal component to survey data

Reduces cost burden Reduces cost burden Re-contacting survey respondents for follow-up Re-contacting survey respondents for follow-up

information can be expensiveinformation can be expensive Increases accuracy and detail of data Increases accuracy and detail of data

collectedcollected

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How Records are LinkedHow Records are LinkedNCHS RecordsNCHS RecordsSSNNameDoBSexState of BirthRaceState of ResidenceMarital Status

Administrative RecordsAdministrative Records

NameDoBSexState of BirthRaceState of ResidenceMarital Status

Non matchesPotential matchesScoring system, clerical review

True matches Non matches

Linked Data FileLinked Data File

NCHS RecordsNCHS RecordsSSNNameDoBSexState of BirthRaceState of ResidenceMarital Status

Administrative RecordsAdministrative RecordsSSNNameDoBSexState of BirthRaceState of ResidenceMarital Status

Non matchesPotential matchesScoring system, clerical review

True matches Non matches

Linked Data FileLinked Data File

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Research Potential of Research Potential of NCHS Linked DataNCHS Linked Data

AgingAging Risk factors for poor health outcomes (hip fractures, stroke, Risk factors for poor health outcomes (hip fractures, stroke,

etc.)etc.) DisabilityDisability

Effects of chronic illness and obesity on disability and Effects of chronic illness and obesity on disability and mortalitymortality

DisparitiesDisparities Mortality patterns by race/ethnicity or socioeconomic statusMortality patterns by race/ethnicity or socioeconomic status

Health servicesHealth services Functional impairment and health care costsFunctional impairment and health care costs

Methodologic StudiesMethodologic Studies Validation of self-reports vs. administrative recordsValidation of self-reports vs. administrative records

GeneticsGenetics Genetic variants and health outcomesGenetic variants and health outcomes

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Record Linkage ActivitiesRecord Linkage Activities

Mortality Mortality National Death IndexNational Death Index

Social Security Retirement and DisabilitySocial Security Retirement and Disability Data from the Retirement, Survivors, Data from the Retirement, Survivors,

Disability Insurance (RSDI) and Disability Insurance (RSDI) and Supplemental Security Income (SSI) Supplemental Security Income (SSI) programsprograms

Medicare enrollment and paymentsMedicare enrollment and payments Enrollment and claims dataEnrollment and claims data

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NCHS Linked Mortality Data NCHS Linked Mortality Data FilesFiles

XX

XX

XX†

XX†

XX

XX

XX

XX†

XX†

Restricted-use

XX†NHIS 2001-2004NHIS 2001-2004

XXNNHS 1985NNHS 1985

NNHS 1995, 1997, NNHS 1995, 1997, 20042004

XX†NHANES 1999-2004NHANES 1999-2004

XX†XXXXNHANES III (1988-NHANES III (1988-1994)1994)

XXXXNHANES II (1976-NHANES II (1976-1980)1980)

XXXXNHEFS (1971-1992)NHEFS (1971-1992)

XXXXXXLSOA II (1994-2000)LSOA II (1994-2000)

XX†XXXXNHIS 1986-2000NHIS 1986-2000

Public-usePublic-useRestricted-use

Future Linkage (death data through

2006)

Completed Linkage(death data through

2000/2002)NCHS Health SurveysNCHS Health Surveys

† Children includedChildren included

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Number of Deaths by Number of Deaths by SurveySurvey

3,384NHANES III

4,143NHANES II

6,656NHEFS

3,958LSOA II

121,138NHIS 1986-2000

Total DeathsNCHS Survey

NHIS and LSOA II have mortality follow-up through 12/31/2002.NHEFS, NHANES II and III have mortality follow-up through

12/31/2000.

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Public-use Linked Public-use Linked Mortality FilesMortality Files

In 2007, released public-use files with a In 2007, released public-use files with a limited amount of perturbed data and limited amount of perturbed data and reduced number of mortality variablesreduced number of mortality variables NHIS 1986-2000NHIS 1986-2000 NHANES IIINHANES III LSOA IILSOA II

Study comparing analyses from public-use Study comparing analyses from public-use and restricted-use linked mortality files and restricted-use linked mortality files demonstrated similar resultsdemonstrated similar results Lochner et al. Am. J. Epidemiol. 2008 168: 336-Lochner et al. Am. J. Epidemiol. 2008 168: 336-

344344

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Mortality Data ElementsMortality Data Elements

Vital statusVital status Date of death or follow-up timeDate of death or follow-up time Underlying cause of deathUnderlying cause of death Multiple cause of death* Multiple cause of death* Age at death*Age at death* Age last presumed alive*Age last presumed alive*

*only available on restricted-use files*only available on restricted-use files

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Research Potential of Research Potential of Linked Mortality DataLinked Mortality Data

Excess Deaths Associated with Underweight, Overweight, and ObesityKM Flegal, BI Graubard, DF Williamson, MH Gail; JAMA, 2005;293:1861-1867.

Living and Dying in the USA: Behavioral, Health, and Social Differentials of Adult Mortality RG Rogers, CB Nam, RA Hummer; 2000.

Suicide among male veterans: a prospective population-based study MS Kaplan, N Huguet, BH McFarland, JT Newsom; J Epidemiol Community Health, 2007; 61:619-624.

Epidemiology

& Community Health

Journal of

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XXNHANES II (1976-1980)NHANES II (1976-1980)

Future LinkageCMS data 1999-

2007Completed Linkage

CMS data 1991-2000

X

X

X

X

X

X

X

NNHS 1997, 2004NNHS 1997, 2004

NHANES 1999-2004NHANES 1999-2004

XNHANES III (1988-1994)NHANES III (1988-1994)

XNHIS 1994-1998NHIS 1994-1998

NHIS 1999-2005NHIS 1999-2005

XLSOA II (1994-2000)LSOA II (1994-2000)

XNHEFS (1971-1992)NHEFS (1971-1992)

NCHS Linked Medicare Data NCHS Linked Medicare Data FilesFiles

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Medicare LinkageMedicare Linkage Medicare enrollment and claims data for the Medicare enrollment and claims data for the

years 1991-2000 years 1991-2000 Denominator fileDenominator file MEDPAR Inpatient hospitalizationMEDPAR Inpatient hospitalization MEDPAR Skilled nursing facility (SNF)MEDPAR Skilled nursing facility (SNF) Hospital outpatientHospital outpatient Home Health Agency (HHA)Home Health Agency (HHA) HospiceHospice Carrier (physician/supplier Part B file)Carrier (physician/supplier Part B file) Durable Medical Equipment (DMERC)Durable Medical Equipment (DMERC)

Next data release (1999-2007)Next data release (1999-2007) All of the above filesAll of the above files Chronic Conditions WarehouseChronic Conditions Warehouse

Medicare Part D (Prescription Drugs)Medicare Part D (Prescription Drugs)

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Summary Medicare Data Summary Medicare Data FileFile

Summary Medicare Enrollment and Claims Summary Medicare Enrollment and Claims Files (SMEC) for 1991-2000Files (SMEC) for 1991-2000 Enrollment information from the Denominator Enrollment information from the Denominator

file plus summary variables of claims and file plus summary variables of claims and paymentspayments

Variables modeled after MCBS cost and use Variables modeled after MCBS cost and use filesfiles

Total reimbursements per yearTotal reimbursements per year Total number of claims by Medicare record type Total number of claims by Medicare record type Summary of charges by Medicare record typeSummary of charges by Medicare record type Termination status & reason for terminationTermination status & reason for termination Monthly HMO enrollmentMonthly HMO enrollment Medicare status code (i.e. Part A, B or both) Medicare status code (i.e. Part A, B or both)

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Research Potential of Research Potential of Linked Medicare DataLinked Medicare Data

Examine risk factors for health Examine risk factors for health conditionsconditions

Examine reliability of survey dataExamine reliability of survey data Compare survey reported Medicare Compare survey reported Medicare

enrollment to Medicare claims recordsenrollment to Medicare claims records Examine survey report of disability with Examine survey report of disability with

program participation eligibility criteriaprogram participation eligibility criteria Examine disparities in Medicare Examine disparities in Medicare

service utilizationservice utilization

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Future LinkageSSA data 1962-

2007

Completed LinkageSSA data 1962-

2003

XX

XX

XX

XX

XX

XXNHANES 1999-2004NHANES 1999-2004

XXNHANES III (1988-1994)NHANES III (1988-1994)

XXNNHS 1985NNHS 1985

XXNHIS 1994-1998NHIS 1994-1998

XXNHIS 1999-2005NHIS 1999-2005

XXLSOA II (1994-2000)LSOA II (1994-2000)

XXNNHS 1995, 1997, 2004NNHS 1995, 1997, 2004

XXNHEFS (1971-1992)NHEFS (1971-1992)

NCHS Linked SSA Data FilesNCHS Linked SSA Data Files

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Social Security LinkageSocial Security Linkage

Old Age, Survivor, & Disability IncomeOld Age, Survivor, & Disability Income Master Beneficiary Record (MBR), 1962 - 2003Master Beneficiary Record (MBR), 1962 - 2003

Program eligibility, benefit amount, payment status, Program eligibility, benefit amount, payment status, dual entitlement dual entitlement

Payment History Update System (PHUS), 1984-2003Payment History Update System (PHUS), 1984-2003 Benefit payment amounts, including withholding Benefit payment amounts, including withholding

information for Medicare Part B premiums information for Medicare Part B premiums

Supplemental Security IncomeSupplemental Security Income Supplemental Security Record (SSR), 1974 - 2003Supplemental Security Record (SSR), 1974 - 2003

Program eligibility, benefit information, and payment Program eligibility, benefit information, and payment statusstatus

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Research Potential of Research Potential of Linked Social Security Linked Social Security

DataData Examine reliability of survey information for SSA Examine reliability of survey information for SSA program participation and benefitsprogram participation and benefits

Compare the health characteristics of early Compare the health characteristics of early retirees (age 62) to those who postpone benefits retirees (age 62) to those who postpone benefits

Policy analysis using validated survey dataPolicy analysis using validated survey data Predicting the number of people who will become Predicting the number of people who will become

disabled based upon survey reported health conditions disabled based upon survey reported health conditions Determining whether current disability entitlement Determining whether current disability entitlement

funding levels will be adequate as the population agesfunding levels will be adequate as the population ages

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Future Linkage ActivitiesFuture Linkage Activities Linkage of 1999-2004 Medicaid Linkage of 1999-2004 Medicaid

enrollment and claims data linked to enrollment and claims data linked to 1999-2004 NHIS and NHANES 1999-2004 NHIS and NHANES

NCHS series report comparing the NCHS series report comparing the mortality experience of the 1986-mortality experience of the 1986-2000 National Health Interview 2000 National Health Interview Survey Participants with the U.S. Survey Participants with the U.S. populationpopulation

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OverviewOverview

NCHS Record Linkage Program NCHS Record Linkage Program




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Record Linkage ProgramRecord Linkage ProgramAnalytic Issues and ToolsAnalytic Issues and Tools

Kimberly A. Lochner, SPB, OAENCHS Data Users Conference

August 12, 2008

U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES

Centers for Disease Control and PreventionNational Center for Health Statistics

23

Analytic Issues: Analytic Issues: OverviewOverview

Linkage eligibilityLinkage eligibility Linkage match statusLinkage match status Combining survey years for the Combining survey years for the

linked mortality fileslinked mortality files Changes in surveys or administrative Changes in surveys or administrative

data over timedata over time Issues with administrative dataIssues with administrative data

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Mortality: Analytic IssuesMortality: Analytic Issues

Eligibility statusEligibility status Sample weightsSample weights

Combining survey years for the linked Combining survey years for the linked mortality filesmortality files Variance estimationVariance estimation

Changes over timeChanges over time ICD-9 and ICD-10 codes ICD-9 and ICD-10 codes

Most of these issues apply only to the Most of these issues apply only to the NHIS Linked Mortality FilesNHIS Linked Mortality Files

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Eligibility StatusEligibility Status

What determines eligibility for What determines eligibility for mortality follow-up?mortality follow-up? AgeAge

Non “adult” survey respondents are Non “adult” survey respondents are INELIGIBLEINELIGIBLE

Future linkages will include childrenFuture linkages will include children

Sufficient data for matchingSufficient data for matching Lack of identifying data makes you Lack of identifying data makes you INELIGIBLEINELIGIBLE

Drop Drop INELIGIBLEINELIGIBLE survey respondents survey respondents Variable indicating eligibility status on Variable indicating eligibility status on

files files

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Mortality Ineligibility:Mortality Ineligibility:Lack of Matching Data (adults Lack of Matching Data (adults

only)only)

0.00.0NHEFSNHEFS

0.130.13NHANES IIINHANES III

0.00.0NHANES IINHANES II

8.0 – 11.08.0 – 11.0NHIS 1997-2000NHIS 1997-2000

2.0 – 3.02.0 – 3.0NHIS 1992-1996NHIS 1992-1996

< 2.0< 2.0NHIS 1986 - 1991NHIS 1986 - 1991

% Ineligible% IneligibleNCHS Health SurveyNCHS Health Survey

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Eligibility StatusEligibility Status

Ineligibility a problem for NHISIneligibility a problem for NHIS Created new sample weights to Created new sample weights to

account for ineligibility due to account for ineligibility due to insufficient identifying datainsufficient identifying data Original NHIS sample weights (WTFA)Original NHIS sample weights (WTFA) New NHIS sample weights (WGT_NEW)New NHIS sample weights (WGT_NEW)

Only for core/person filesOnly for core/person files

Recommend using WGT_NEWRecommend using WGT_NEW

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Combining Survey YearsCombining Survey Years

NHIS linked mortality files cover two NHIS linked mortality files cover two design periods (1986-1994 and 1995-design periods (1986-1994 and 1995-2000)2000) Follow guidelines on pooling NHIS yearsFollow guidelines on pooling NHIS years

http://www.cdc.gov/nchs/nhis/methods.htmhttp://www.cdc.gov/nchs/nhis/methods.htm

Created new stratum and psu Created new stratum and psu variables for NHIS Linked Mortality variables for NHIS Linked Mortality files to allow combining across NHIS files to allow combining across NHIS design yearsdesign years

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Changes in Data Over Changes in Data Over TimeTime

ICD-9 (deaths 1979 – 1998) and ICD-10 (deaths ICD-9 (deaths 1979 – 1998) and ICD-10 (deaths 1999 to present) cover linked mortality files1999 to present) cover linked mortality files

Use both sets of codes to obtain full counts of Use both sets of codes to obtain full counts of cause-specific deaths cause-specific deaths Individual codes (ICD_9REV, ICD_10REV)Individual codes (ICD_9REV, ICD_10REV) Recodes Recodes

UCOD_282, (ICD-9)UCOD_282, (ICD-9) UCOD_72, (ICD-9)UCOD_72, (ICD-9) UCOD_34, (ICD-9)UCOD_34, (ICD-9) UCOD_358, (ICD-10)UCOD_358, (ICD-10)

UCOD_113 - recodes deaths before 1998 using UCOD_113 - recodes deaths before 1998 using ICD-10 guidelines ICD-10 guidelines

Refer to vital statistics report on ICD comparabilityRefer to vital statistics report on ICD comparability

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Medicare: Analytic IssuesMedicare: Analytic Issues

Eligibility statusEligibility status Eligible but not matchedEligible but not matched DeathDeath Linked but no Medicare dataLinked but no Medicare data Managed care enrollmentManaged care enrollment Non covered servicesNon covered services Gaps in coverageGaps in coverage Issues with Medicare data filesIssues with Medicare data files

See the NCHS-CMS linkage web page under See the NCHS-CMS linkage web page under “Analytic/Programming Support”“Analytic/Programming Support”

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Medicare Ineligible Population Medicare Ineligible Population and Linkage Rates (65+ years)and Linkage Rates (65+ years)

95.995.91.91.9NHANES IIINHANES III81.081.00.00.0NHANES IINHANES II84.984.97.17.1NHEFSNHEFS96.296.220.420.4LSOA IILSOA II92.492.440.340.3NHIS 1998NHIS 199893.793.730.730.7NHIS 1997NHIS 1997

92.192.122.222.2NHIS 1996NHIS 199692.892.819.319.3NHIS 1995NHIS 199592.892.817.917.9NHIS 1994NHIS 1994

% Linked among eligible% Linked among eligible% Ineligible% IneligibleNCHS NCHS

Health SurveyHealth Survey

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Ineligibles and Non-Ineligibles and Non-MatchesMatches

Must be excluded from your sampleMust be excluded from your sample

Identify using the variable Identify using the variable (CMS_MATCH) on the Feasibility (CMS_MATCH) on the Feasibility Study Data filesStudy Data files

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Identifying DeathsIdentifying Deaths

Survey participants interviewed before Survey participants interviewed before the availability of linked Medicare files the availability of linked Medicare files could have died before 1991could have died before 1991 E.g. NHEFS, NHANES II or NHANES III E.g. NHEFS, NHANES II or NHANES III

respondents interviewed in Phase I (1988-respondents interviewed in Phase I (1988-91)91)

Persons may die during study period and Persons may die during study period and cease to have Medicare recordscease to have Medicare records Enrolled in Medicare in 1991 but died before Enrolled in Medicare in 1991 but died before

20002000

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Identifying DeathsIdentifying Deaths Survey respondents who died before 1991 Survey respondents who died before 1991

(e.g. from NHANES) can be identified by (e.g. from NHANES) can be identified by merging mortality information from the merging mortality information from the Linked Mortality filesLinked Mortality files Needed to create analytic sampleNeeded to create analytic sample

Persons who died during 1991-2000 Persons who died during 1991-2000 should no longer have Medicare records should no longer have Medicare records after date of deathafter date of death Look for a CMS date of death (DOD) on each of Look for a CMS date of death (DOD) on each of

the Denominator or SMEC files (1991 to 2000)the Denominator or SMEC files (1991 to 2000)

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Linked but no Medicare Linked but no Medicare datadata

No denominator file becauseNo denominator file because Loss of entitlement during 1991-2000Loss of entitlement during 1991-2000 Deceased prior to 1991Deceased prior to 1991 CMS record keeping inconsistenciesCMS record keeping inconsistencies

No claims dataNo claims data Not utilizing Medicare in 1991-2000Not utilizing Medicare in 1991-2000 No reimbursable claimsNo reimbursable claims CMS record keeping inconsistenciesCMS record keeping inconsistencies

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No Denominator RecordNo Denominator Record

Lack of denominator record can Lack of denominator record can affect your analytic sample – why?affect your analytic sample – why?

Can’t determine managed care Can’t determine managed care enrollmentenrollment

In general, managed care enrollees are In general, managed care enrollees are excluded from sample (more on this to excluded from sample (more on this to come)come)

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Managed Care Managed Care EnrollmentEnrollment

Medicare does not receive claims for Medicare does not receive claims for beneficiaries enrolled in managed beneficiaries enrolled in managed care plans (HMO)care plans (HMO) Do not have complete information on Do not have complete information on

payments or services receivedpayments or services received Could miss health events that are being Could miss health events that are being

counted based upon submitted claimscounted based upon submitted claims Complex issue. Refer to ResDACComplex issue. Refer to ResDAC

http://http://www.resdac.umn.eduwww.resdac.umn.edu//

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How managed care enrollees How managed care enrollees affect your research depends upon affect your research depends upon

your question…your question… Studies on reimbursements/chargesStudies on reimbursements/charges

Option may be to exclude those with any managed care Option may be to exclude those with any managed care enrollment because you don’t have complete enrollment because you don’t have complete information on payments or services receivedinformation on payments or services received

Studies on health outcomes/eventsStudies on health outcomes/events Option may be to exclude those with any managed care Option may be to exclude those with any managed care

enrollment because you could miss eventsenrollment because you could miss events Option may be to censor observations at time of first Option may be to censor observations at time of first

HMO enrollmentHMO enrollment Other methods for addressing HMO enrollment Other methods for addressing HMO enrollment

possible depending upon research questionpossible depending upon research question

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Services not covered in Services not covered in Medicare 1991-2000 filesMedicare 1991-2000 files

Out-patient prescription drugsOut-patient prescription drugs Routine physical and dental examsRoutine physical and dental exams DenturesDentures Eye glassesEye glasses Out-of-pocket expenses for Medicare Out-of-pocket expenses for Medicare

beneficiaries (e.g. deductibles, beneficiaries (e.g. deductibles, coinsurance)coinsurance)

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SSA: Analytic IssuesSSA: Analytic Issues

Eligibility statusEligibility status Eligible but not matched Eligible but not matched Linked but no benefit history dataLinked but no benefit history data Records are extracted from files Records are extracted from files

designed for program administration designed for program administration - not for research- not for research

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SSA Ineligible Population SSA Ineligible Population and and

Linkage RatesLinkage Rates

93.393.35.65.6NNHS 1985NNHS 1985

95.395.32.92.9NHANES IIINHANES III

94.694.66.06.0NHEFSNHEFS

97.697.619.119.1LSOA IILSOA II

86.786.737.737.7NHIS 1998NHIS 1998

88.088.031.431.4NHIS 1997NHIS 1997

89.189.125.325.3NHIS 1996NHIS 1996

90.290.220.520.5NHIS 1995NHIS 1995

91.791.718.618.6NHIS 1994NHIS 1994

% Linked among Eligible% Linked among Eligible% Ineligible% IneligibleNCHS Health NCHS Health SurveysSurveys

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Ineligibles and Non-Ineligibles and Non-MatchesMatches

Must be excluded from your sampleMust be excluded from your sample

Identify using the variable Identify using the variable (SSA_MATCH) on the Feasibility Study (SSA_MATCH) on the Feasibility Study Data filesData files

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Linked but no SSA DataLinked but no SSA Data

Linkage is to SSA NUMIDENT file Linkage is to SSA NUMIDENT file Linked to NUMIDENT file but may not Linked to NUMIDENT file but may not

be eligible for Social Security benefitsbe eligible for Social Security benefits Not age eligible for retirementNot age eligible for retirement Defer retirement benefits because Defer retirement benefits because

working full-timeworking full-time Not eligible for Social SecurityNot eligible for Social Security

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Issues with Issues with Administrative DataAdministrative Data

Administrative data updates Administrative data updates Payment history updatesPayment history updates Previously denied claims may be overriddenPreviously denied claims may be overridden Changes to type of benefit statusChanges to type of benefit status

Individuals receiving disability (DI) switch to Individuals receiving disability (DI) switch to retirement (R) benefits at age 65 in RSDI programretirement (R) benefits at age 65 in RSDI program

Complicated dataComplicated data File layouts are complex, e.g. each MBR record File layouts are complex, e.g. each MBR record

has 2 partshas 2 parts Calculation of benefits not straightforward, e.g. Calculation of benefits not straightforward, e.g.

SSI benefits come from both federal and state SSI benefits come from both federal and state programsprograms

46

Final TipsFinal Tips Read relevant documentation !!! Read relevant documentation !!!

Survey file layouts & detailed notesSurvey file layouts & detailed notes Linkage methodology reportsLinkage methodology reports Sample SAS & STATA input statements for Sample SAS & STATA input statements for

public-use linked mortality filespublic-use linked mortality files Analytic guidelinesAnalytic guidelines

Consult basic program informationConsult basic program information CMS – CMS – http://http://www.cms.govwww.cms.gov ResDAC – ResDAC – http://http://www.resdac.umn.eduwww.resdac.umn.edu (Medicare)(Medicare) SSA – SSA – http://http://www.ssa.govwww.ssa.gov andandhttp://http://www.ssa.gov/regulations/index.htmwww.ssa.gov/regulations/index.htm

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Final TipsFinal Tips

Determine NCHS public-use files neededDetermine NCHS public-use files needed Determine RDC linked files neededDetermine RDC linked files needed Determine feasibility of research question Determine feasibility of research question

based upon successfully linked respondentsbased upon successfully linked respondents Public-use Public-use Feasibility Study Data filesFeasibility Study Data files

available indicating whether respondent was available indicating whether respondent was linked to Medicare or SSA data and whether linked to Medicare or SSA data and whether there is a record on the various Medicare and/or there is a record on the various Medicare and/or SSA files SSA files

Match status (SSA_MATCH & CMS_MATCH)Match status (SSA_MATCH & CMS_MATCH)

48

OverviewOverview





49


Record Linkage ProgramRecord Linkage Program

Comparative Analysis of the Public-use and Comparative Analysis of the Public-use and Restricted-use Linked Mortality FilesRestricted-use Linked Mortality Files

Kimberly A. Lochner, SPB, OAENCHS Data Users Conference

August 12, 2008

U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICESCenters for Disease Control and Prevention

National Center for Health Statistics

50

ObjectivesObjectives Present an overview of the newlyPresent an overview of the newly available available

public-use linked mortality filespublic-use linked mortality files National Health Interview Survey (NHIS) 1986 to National Health Interview Survey (NHIS) 1986 to

20002000 Third National Health a Nutrition Examination Third National Health a Nutrition Examination

Survey (NHANES III)Survey (NHANES III) The Second Longitudinal Study of Aging (LSOA The Second Longitudinal Study of Aging (LSOA

II)II)

Demonstrate the analytic comparability Demonstrate the analytic comparability between the public-use and restricted-use between the public-use and restricted-use versions of the linked mortality filesversions of the linked mortality files

51

BackgroundBackground

Mortality follow-up studies are a major Mortality follow-up studies are a major focus of NCHS record linkage activitiesfocus of NCHS record linkage activities

NCHS linked mortality files created in NCHS linked mortality files created in 2004 made available through NCHS 2004 made available through NCHS Research Data Center (RDC)Research Data Center (RDC) Protects confidentiality of survey Protects confidentiality of survey

participantsparticipants May minimize access to highly utilized May minimize access to highly utilized

data sourcesdata sources

52

BackgroundBackground

NCHS plan for public-use linked NCHS plan for public-use linked mortality files includedmortality files included Releasing a Releasing a reduced number of key reduced number of key

mortality variablesmortality variables Perturbing date or cause of death for Perturbing date or cause of death for

select recordsselect records Determining that survey participants Determining that survey participants

could not be reidentifiedcould not be reidentified Comparing the analytic utility of the Comparing the analytic utility of the

public-use file to the restricted-use filepublic-use file to the restricted-use file

53

Public-use Linked Mortality Public-use Linked Mortality FilesFiles

NHIS (1986 – 2000) NHIS (1986 – 2000) Each NHIS year is nationally representative Each NHIS year is nationally representative

survey of the civilian non-institutionalized survey of the civilian non-institutionalized U.S. populationU.S. population

Questionnaire contentQuestionnaire content Basic socio-demographic characteristicsBasic socio-demographic characteristics Health conditions and utilizationHealth conditions and utilization Health status, health care services, and Health status, health care services, and

behaviorbehavior Mortality follow-up through December 2002Mortality follow-up through December 2002

54


NHANES III (1988 – 1994) NHANES III (1988 – 1994) Includes survey and examination information Includes survey and examination information

designed to assess the health and nutritional designed to assess the health and nutritional status of U.S. adults and children. status of U.S. adults and children.

Study contentStudy content Basic socio-demographic characteristicsBasic socio-demographic characteristics Medical and dental examinationsMedical and dental examinations Laboratory testsLaboratory tests Environmental exposuresEnvironmental exposures

Mortality follow-up through December 2000Mortality follow-up through December 2000

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LSOA IILSOA II Prospective survey of persons 70 years of Prospective survey of persons 70 years of

age and over at the time of their baseline age and over at the time of their baseline interview (1994 NHIS)interview (1994 NHIS)

Follow-up interviews in 1997-98 and 1999-00Follow-up interviews in 1997-98 and 1999-00 Questionnaire contentQuestionnaire content

Basic socio-demographic characteristicsBasic socio-demographic characteristics Health conditions, functional health status and Health conditions, functional health status and

disabilitydisability Health care utilizationHealth care utilization

Mortality follow-up through December 2002Mortality follow-up through December 2002

56

Data Elements: Data Elements: NHIS Linked Mortality NHIS Linked Mortality

FilesFiles

Yes (quarter, year)**Yes (quarter, year)**Yes (month, day, year)Yes (month, day, year)Interview dateInterview date

Yes (month, year)**Yes (month, year)**Yes (month, day, year)Yes (month, day, year)Date of birthDate of birth

NoNoYesYesAge last presumed aliveAge last presumed alive

NoNoYesYesAge at deathAge at death

Yes (top coded at 85+)Yes (top coded at 85+)YesYesAge at interviewAge at interview

Yes*Yes*YesYesMultiple cause-of-deathMultiple cause-of-death

Yes (grouped recode)Yes (grouped recode)YesYesUnderlying cause-of-deathUnderlying cause-of-death

Yes (quarter, year)Yes (quarter, year)Yes (month, day, year)Yes (month, day, year)Death dateDeath date

YesYesYesYesFinal mortality statusFinal mortality status

Public-usePublic-useRestricted-useRestricted-useSurvey VariablesSurvey Variables

* MCOD flags only for diabetes, hypertension, and hip fracture**Available on the public-use NHIS survey data files

57

Data Elements: Data Elements: NHANES III Linked Mortality NHANES III Linked Mortality

FilesFiles

YesYesYesYesMortality sourceMortality source

YesYesNoNoPerson months FUPerson months FU

NoNoYes (month, day, year)Yes (month, day, year)Interview dateInterview date

NoNoYes (month, day, year)Yes (month, day, year)Death dateDeath date

NoNoYes (month, day, year)Yes (month, day, year)Date of birthDate of birth



Yes**Yes**YesYesAge at interview/examAge at interview/exam




Public-usePublic-useRestricted-useRestricted-use Survey VariablesSurvey Variables

* MCOD flags only for diabetes, hypertension, and hip fracture* MCOD flags only for diabetes, hypertension, and hip fracture**Available on the public-use NHANESIII survey data files**Available on the public-use NHANESIII survey data files

58

Data Elements: Data Elements: LSOA II Linked Mortality FilesLSOA II Linked Mortality Files

YesYesYesYesMortality sourceMortality source

Yes (month, year)Yes (month, year)Yes (month, day, year)Yes (month, day, year)Interview dateInterview date

Yes (month, year)**Yes (month, year)**Yes (month, day, year)Yes (month, day, year)Date of birthDate of birth



Yes Yes YesYesAge at interviewAge at interview



Yes (quarter, year)Yes (quarter, year)Yes (month, day, year)Yes (month, day, year)Death dateDeath date


Public-usePublic-useRestricted-useRestricted-use Survey VariablesSurvey Variables

* MCOD flags only for diabetes, hypertension, and hip fracture**Available on the public-use LSOA II survey data files

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Comparative AnalysesComparative Analyses

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Statistical MethodsStatistical Methods

Compared mean follow-up times and Compared mean follow-up times and distributions for select causes of deathdistributions for select causes of death

Compared the mortality risk for a Compared the mortality risk for a standard set of socio-demographic standard set of socio-demographic covariates for all-cause as well as covariates for all-cause as well as cause-specific mortality cause-specific mortality Cox proportional hazard modelsCox proportional hazard models SUDAAN to take into account complex SUDAAN to take into account complex

survey designsurvey design

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Analytic SamplesAnalytic Samples

Eligible for mortality follow-upEligible for mortality follow-up At least 25 years of age at the time At least 25 years of age at the time

of the survey interviewof the survey interview Non-Hispanic white, non-Hispanic Non-Hispanic white, non-Hispanic

black, or Hispanicblack, or Hispanic Non missing values for cause of Non missing values for cause of

death or other covariatesdeath or other covariates

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CovariatesCovariates

Socio-demographic characteristics reportedSocio-demographic characteristics reportedat time of interview and taken from public-at time of interview and taken from public-

useusesurvey data files: survey data files: Age Age Sex Sex Race and ethnicity Race and ethnicity Educational attainment Educational attainment Marital status (except NHANES III)Marital status (except NHANES III) Region of the country (except NHANES III)Region of the country (except NHANES III)

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OutcomesOutcomes All-cause and cause-specific mortalityAll-cause and cause-specific mortality

Cause-specific deaths based on underlying cause Cause-specific deaths based on underlying cause of death from the ICD-10 113 grouped recodeof death from the ICD-10 113 grouped recode

Duration of follow-up calculated from time of Duration of follow-up calculated from time of interview until death or censored at end of interview until death or censored at end of the follow-up periodthe follow-up period Restricted-use files use complete information on Restricted-use files use complete information on

interview and death month, day, and yearinterview and death month, day, and year Public-use files use less detailed information on Public-use files use less detailed information on

timing of death, some of which is perturbedtiming of death, some of which is perturbed NHIS/LSOA II: use interview year and death year onlyNHIS/LSOA II: use interview year and death year only NHANES III: use person-time follow-up provided on the NHANES III: use person-time follow-up provided on the

filefile

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NHIS ResultsNHIS Results

Sample (n = 897,232)Sample (n = 897,232) Deaths (n = 114,264)Deaths (n = 114,264)

11.8% weighted 11.8% weighted Follow-up (mean)Follow-up (mean)

Restricted-use = 8.6 yearsRestricted-use = 8.6 years Public-use = 8.7 yearsPublic-use = 8.7 years

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NHIS Linked Mortality Files: NHIS Linked Mortality Files: Cause-specific DeathsCause-specific Deaths

1.11.11,1171,1171.01.01,0971,097SuicideSuicide

HomicideHomicide

Unint. injuryUnint. injury

Liver dis./Cirr.Liver dis./Cirr.

DiabetesDiabetes

StrokeStroke

ProstateProstate

BreastBreast

ColorectalColorectal

LungLung

Cancer (all)Cancer (all)

IschemicIschemic

Heart diseaseHeart disease

Cause of Cause of DeathDeath

0.40.44254250.30.3410410

2.92.93,2943,2942.92.93,2423,242

1.11.11,2681,2681.11.11,2381,238

2.92.93,3843,3842.92.93,3613,361

6.86.87,8557,8556.86.87,8027,802

3.03.01,7861,7863.03.01,7621,762

4.24.22,3722,3724.34.32,4212,421

2.72.73,0943,0942.62.63,0443,044

7.47.48,3958,3957.87.88,8388,838

26.526.530,19730,19726.626.630,22030,220

9.89.811,29011,29010.010.011,43411,434

32.032.036,68936,68932.532.537,27237,272

Percentage Percentage (weighted)(weighted)

Number Number (unweighted)(unweighted)



Restricted-useRestricted-usePublic-usePublic-use

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NHIS Linked Mortality Files: NHIS Linked Mortality Files: Relative Hazards for All-Cause Relative Hazards for All-Cause

MortalityMortality

1.281.281.281.28 Some collegeSome college

1.411.411.411.41 High school or GEDHigh school or GED

1.681.681.681.68 Less than high schoolLess than high school

Educational attainment (College grad +)Educational attainment (College grad +)

0.890.890.890.89 HispanicHispanic

1.151.151.151.15 NHBNHB

Race/ethnicity (NHW)Race/ethnicity (NHW)

1.691.691.691.69 MaleMale

Sex (female)Sex (female)

1.091.091.091.09Age (years)Age (years)

Restricted-useRestricted-usePublic-usePublic-useCovariatesCovariates

Note: Models also adjusted for marital status and region of the country.

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NHIS Linked Mortality Files: NHIS Linked Mortality Files: Relative Hazards for Homicide Relative Hazards for Homicide

MortalityMortality

1.551.551.651.65 High school or GEDHigh school or GED


Educational attainment (More than high school)Educational attainment (More than high school)

3.903.904.004.00 NHBNHB

Race/ethnicity (NHW)Race/ethnicity (NHW)

2.702.702.702.70 MaleMale

Sex (female)Sex (female)


Restricted-useRestricted-usePublic-usePublic-useCovariatesCovariates

Note: Models are restricted to Non Hispanic Whites and Blacks (n = 802,307). Models also adjusted for marital status and region of the country

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NHANES III ResultsNHANES III Results



Restricted-use = 104.1 monthsRestricted-use = 104.1 months Public-use = 103.8 monthsPublic-use = 103.8 months

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NHANES III Linked Mortality NHANES III Linked Mortality Files: Files:

Cause-specific DeathsCause-specific Deaths

StrokeStroke

LungLung


IschemicIschemic


Causes of Causes of DeathDeath

7.07.02692696.96.9266266

7.67.61791797.67.6180180

25.325.369869825.025.0689689

11.311.333633611.411.4344344

34.834.81,1581,15835.535.51,1881,188






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NHANES III Linked Mortality File: NHANES III Linked Mortality File: Relative Hazards for All-Cause Relative Hazards for All-Cause

MortalityMortality

1.281.281.281.28 High schoolHigh school


Educational attainment (More than high Educational attainment (More than high school)school)

0.990.990.990.99 Mexican-AmericanMexican-American

1.381.381.381.38 Non Hispanic BlackNon Hispanic Black

Race/ethnicity (Non Hispanic White)Race/ethnicity (Non Hispanic White)

1.461.461.461.46 MaleMale

Sex (Female)Sex (Female)


Restricted-useRestricted-usePublic-use Public-use CovariatesCovariates

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NHANES III Linked Mortality File: NHANES III Linked Mortality File: Relative Hazards for Relative Hazards for

Cerebrovascular MortalityCerebrovascular Mortality



Educational attainment (More than high Educational attainment (More than high school)school)



1.101.101.111.11 MaleMale




Note: Models restricted to Non Hispanic Whites and Blacks (n = 11,985).

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LSOA II ResultsLSOA II Results



Restricted-use = 4.4 yearsRestricted-use = 4.4 years Public-use = 4.4 yearsPublic-use = 4.4 years

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LSOA II Linked Mortality Files: LSOA II Linked Mortality Files: Cause-specific DeathsCause-specific Deaths

StrokeStroke

LungLung


IschemicIschemic


Causes of Causes of DeathDeath

8.38.33133138.38.3312312

5.75.72042045.75.7204204

22.022.080880821.721.7797797

9.09.03383389.09.0340340

34.234.21,2731,27334.934.91,3021,302






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LSOA II Linked Mortality File: LSOA II Linked Mortality File: Relative Hazards for All-Cause Relative Hazards for All-Cause

MortalityMortality

1.921.921.911.91 80-8980-89

Age (70-79)Age (70-79)

0.790.790.780.78 HispanicHispanic

Educational attainment (More than high school)Educational attainment (More than high school)





1.521.521.531.53 MaleMale


3.093.093.113.11 90+90+


Note: Models also adjusted for marital status and region of the country.

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LSOA II Linked Mortality File: LSOA II Linked Mortality File: Relative Hazards for Cancer Relative Hazards for Cancer

MortalityMortality

1.041.041.051.05 WidowedWidowed

1.301.301.291.29 80-8980-89

Age (70-79)Age (70-79)


Marital status (Married)Marital status (Married)

1.081.081.061.06 Divorced/separatedDivorced/separated

1.111.111.141.14 Never marriedNever married


Educational attainment (More then high school)Educational attainment (More then high school)

1.751.751.771.77 MaleMale


0.660.660.620.62 90+90+


Note: Models restricted to Non Hispanic Whites (n = 7,586). Models also adjusted for region of the country.

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ConclusionsConclusions

Public-use linked mortality files yield Public-use linked mortality files yield similar results as the restricted-use datasimilar results as the restricted-use data Public-use and restricted-use files yield Public-use and restricted-use files yield

similar hazard ratios and confidence similar hazard ratios and confidence intervals, particularly for common causes of intervals, particularly for common causes of deathdeath

Results for less common causes of death Results for less common causes of death remain consistent, although there tends to remain consistent, although there tends to be less agreement in the estimatesbe less agreement in the estimates

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ConclusionsConclusions

Caution is urged for analyses of very Caution is urged for analyses of very rare causes of death or small rare causes of death or small population subgroupspopulation subgroups

Users of the public-use linked Users of the public-use linked

mortality files may request to verify mortality files may request to verify their results through the NCHS their results through the NCHS Research Data CenterResearch Data Center

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Public-use Linked Mortality Files Public-use Linked Mortality Files Can Be DownloadedCan Be Downloaded

http://www.cdc.gov/nchs/data_access/data_linkage_activities.htm

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AcknowledgementsAcknowledgements

American Journal of Epidemiology American Journal of Epidemiology 2008 168(3):336-3442008 168(3):336-344

SPB data linkage teamSPB data linkage team Stephanie BarteeStephanie Bartee Jim Brittain Jim Brittain Cordell GoldenCordell Golden Donna MillerDonna Miller Gloria WheatcroftGloria Wheatcroft

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OverviewOverview





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NCHS Record Linkage NCHS Record Linkage Activities: Activities: Accessing Accessing Restricted Linked data at the Restricted Linked data at the NCHS Research Data CenterNCHS Research Data Center

Christine CoxNCHS Data Users ConferenceAugust 12, 2008

U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES

Centers for Disease Control and PreventionNational Center for Health Statistics

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Why can’t you just Why can’t you just give me the data?give me the data?

NCHS does not “own” the linked NCHS does not “own” the linked administrative dataadministrative data

NCHS data confidentiality rules prohibit NCHS data confidentiality rules prohibit the release of potentially identifiable the release of potentially identifiable data – special considerations data – special considerations concerning the protection of linked concerning the protection of linked datadata

The RDC is the only option for access The RDC is the only option for access to restricted-use data filesto restricted-use data files

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Research Data CenterResearch Data Center

The RDC is a organizational unit The RDC is a organizational unit located at NCHS headquarters in located at NCHS headquarters in Hyattsville, MDHyattsville, MD

Provides access to restricted use Provides access to restricted use data filesdata files

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Restricted Data Files Restricted Data Files Include…Include…

Linked administrative dataLinked administrative data MedicareMedicare SSASSA Restricted-use linked mortality filesRestricted-use linked mortality files

Detailed geographic data or Detailed geographic data or contextual datacontextual data Census tract & State/county level dataCensus tract & State/county level data EPA air pollution dataEPA air pollution data

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To gain access to NCHS restricted To gain access to NCHS restricted data user must:data user must:

Submit a research proposalSubmit a research proposal Sign an affidavit of confidentialitySign an affidavit of confidentiality Promise not to use any method to Promise not to use any method to

attempt to identify respondentsattempt to identify respondents

What to Expect?What to Expect?

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What to Expect?What to Expect?

How long for a proposal to be How long for a proposal to be reviewed?reviewed?

Usually within 2 weeks, if proposing to use Usually within 2 weeks, if proposing to use public use survey data with the linked public use survey data with the linked datadata

Up to 1-2 months, if proposing to use non-Up to 1-2 months, if proposing to use non-public survey data with the linked datapublic survey data with the linked data

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Access MethodsAccess Methods Once approved, three methods to access Once approved, three methods to access

restricted datarestricted data on-siteon-site - use local computing resources in the - use local computing resources in the

NCHS RDC, Hyattsville, MDNCHS RDC, Hyattsville, MD remoteremote – submit programs electronically to be – submit programs electronically to be

executed in the RDC with output returned by executed in the RDC with output returned by emailemail

Census RDC-Census RDC- access NCHS data using any one access NCHS data using any one of the nine Census RDCs. of the nine Census RDCs.

For all methods of access, restricted data For all methods of access, restricted data files remain in RDC and output is files remain in RDC and output is inspected for disclosure violationsinspected for disclosure violations

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On-Site Access MethodOn-Site Access Method On-site FacilitiesOn-site Facilities

Four user workstations-expandable as neededFour user workstations-expandable as needed Pentium IV computersPentium IV computers Windows XPWindows XP SAS, STATA, SUDAAN, LIMDEP, SPSS, Watcom Fortran SAS, STATA, SUDAAN, LIMDEP, SPSS, Watcom Fortran

77, & HLM77, & HLM No removable mediaNo removable media Secure printerSecure printer Open only during normal working hoursOpen only during normal working hours

RDC staff constructs necessary data files, RDC staff constructs necessary data files, including merged user dataincluding merged user data

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Remote Access MethodRemote Access Method

RDC staff constructs necessary data files, RDC staff constructs necessary data files, including merged user dataincluding merged user data

SAS programs only, including SAS callable SAS programs only, including SAS callable SUDAAN (certain procedures and SUDAAN (certain procedures and functions not allowed)functions not allowed)

Both submitted programs and output Both submitted programs and output undergo a programmed disclosure undergo a programmed disclosure limitation reviewlimitation review

Ability to submit analytical computer Ability to submit analytical computer programs via email from anywhere in the programs via email from anywhere in the world with access available 24hrs/dayworld with access available 24hrs/day

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Census RDC Census RDC Access MethodAccess Method

9 Census RDCs9 Census RDCs Los Angeles, Berkeley, Boston, Durham, Los Angeles, Berkeley, Boston, Durham,

Ann Arbor, Ithaca, NYC, Chicago, & DCAnn Arbor, Ithaca, NYC, Chicago, & DC Separate Census research proposal is Separate Census research proposal is

not needednot needed May have to follow additional security May have to follow additional security

requirements at Census Bureau facilities requirements at Census Bureau facilities

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User Fees: Linked Data User Fees: Linked Data AccessAccess

Minimum $250 fee per day for Minimum $250 fee per day for analytic file creation.analytic file creation.

Census RDC Access….Census RDC Access….

Minimum $250 fee per day for Minimum $250 fee per day for analytic file creation and $250 per analytic file creation and $250 per month remote access fee.month remote access fee.

Remote Access..........Remote Access..........

Minimum $250 fee per day for Minimum $250 fee per day for analytic file creation and $200 per analytic file creation and $200 per day on-site user fee (2-day minimum; day on-site user fee (2-day minimum; 10-day maximum).10-day maximum).

Guest Researcher (on site)Guest Researcher (on site)……

User FeesUser FeesType of Data AccessType of Data Access

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Proposal RequirementsProposal Requirements Proposal is evaluated by review Proposal is evaluated by review

committee committee Review criteriaReview criteria

Scientific and technical feasibilityScientific and technical feasibility Availability of RDC resourcesAvailability of RDC resources Disclosure risk for restricted informationDisclosure risk for restricted information The extent to which project is in The extent to which project is in

accordance with the mission of NCHSaccordance with the mission of NCHS

Special note:Special note: NCHS does not try to NCHS does not try to determine if proposals are duplicativedetermine if proposals are duplicative

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Proposal Requirements: Proposal Requirements: Helpful TipsHelpful Tips

Be clear about research and data Be clear about research and data requirements (helps to determine requirements (helps to determine feasibility of project)feasibility of project) Clearly identify the sample to be Clearly identify the sample to be

included in the analytic fileincluded in the analytic file Provide data dictionaries for bothProvide data dictionaries for both

Public-use dataPublic-use data Restricted-use dataRestricted-use data

Provide examples of expected outputProvide examples of expected output

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Visit the RDC at: http://www.cdc.gov/nchs/r&d/rdc.htm or email: [email protected]

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Where to get Help?Where to get Help?

RDC website contains:RDC website contains: Proposal ChecklistProposal Checklist Sample ProposalSample Proposal List of available restricted data filesList of available restricted data files Detail on Census RDC locations and contact Detail on Census RDC locations and contact

informationinformation FAQ’s regarding proposal review process, on-FAQ’s regarding proposal review process, on-

site procedures, area information and contact site procedures, area information and contact informationinformation

Email: Email: [email protected]@cdc.gov

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Questions?Questions?

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