# Presentation: 840279

## NCHS Linked Medicare Data for Health Research

- 				Special Projects Branch
- 				Office of Analysis and Epidemiology
- 				NCHS Data Users Conference
- 				August 13, 2008
**U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES**
**Centers for Disease Control and Prevention**
**National Center for Health Statistics**

## NCHS Record Linkage Program

- Links survey data with data collected from administrative records
- Designed to maximize the scientific value of the NCHS population-based surveys
- Examine factors that influence chronic disease, disability,health care utilization, morbidity, and mortality

## What is Record Linkage?

## Record Linkage Activities

- Mortality
- National Death Index
- Social Security Retirement and Disability
- Data from the Retirement, Survivors, Disability Insurance (RSDI) and Supplemental Security Income (SSI) programs
- Medicare enrollment and payments
- Enrollment and claims data

## Medicare 101

- Medicare eligibility groups:
- 65 years and older
- Disabled
- End Stage Renal Disease
- Medicare components during this time period:
- Part A (Hospital insurance)
- Part B (Medical insurance)
- Medicare data:
- Claims based records for covered health services

## Medicare Linkage

- Medicare enrollment and claims data for the years 1991-2000
- Denominator file
- MEDPAR Inpatient hospitalization
- MEDPAR Skilled nursing facility (SNF)
- Hospital outpatient
- Home Health Agency (HHA)
- Hospice
- Carrier (physician/supplier Part B file)
- Durable Medical Equipment (DMERC)
- Next data release (1999-2006)
- All of the above files
- Chronic Conditions Warehouse
- Medicare Part D (Prescription Drugs)

## Medicare Linkage

- Summary Medicare Enrollment and Claims Files (SMEC) for 1991-2000
- Enrollment information from the Denominator file plus summary variables of claims and payments
- Variables modeled after MCBS cost and use files
- Total reimbursements per year
- Total number of claims by Medicare record type
- Summary of charges by Medicare record type
- Termination status & reason for termination
- Monthly HMO enrollment
- Medicare status code (i.e. Part A, B or both)

## NCHS Linked Medicare Data Files 

**NCHS Linked Medicare Data Files **

## Research Potential of Linked Medicare Data

- Examine risk factors for health conditions
- Examine reliability of survey data
- Compare survey reported Medicare enrollment to Medicare claims records
- Examine survey report of disability with program participation eligibility criteria
- Examine disparities in Medicare service utilization

## Medicare: Analytic Issues

- Eligibility status
- Eligible but not matched
- Death
- Linked but no Medicare data
- Managed care enrollment
- Non covered services
- Issues with Medicare data files
- See the NCHS-CMS linkage web page under “Analytic/Programming Support”

## Linkage Ineligibility

- Cannot attempt to link survey records to other data sources if respondent
- Refused to provide SSN; or
- Lacks sufficient key identifying information
- These cases are INELIGIBLE for linkage and MUST BE DROPPED from all analysis
- They are not a random sample of respondents
- More of a problem for NHIS than for NHANES

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

## Ineligibles and Non-Matches

- Must be excluded from your sample
- Identify using the variable (CMS_MATCH) on the Feasibility Study Data

## Identifying Deaths

- Survey participants interviewed before the availability of linked Medicare files could have died before 1991
- E.g. NHEFS, NHANES II or NHANES III
- Persons may die during study period and cease to have Medicare records
- Enrolled in Medicare in 1991 but died before 2000

## Identifying Deaths

- Survey respondents who died before 1991 (e.g. from NHANES) can be identified by merging mortality information from the Linked Mortality files
- Needed to create analytic sample
- Persons who died during 1991-2000 should no longer have Medicare records after date of death
- Look for a CMS date of death (DOD) on each of the Denominator or SMEC files (1991 to 2000)

## No Denominator Record

- Deceased prior to 1991
- check CMS date of death
- Loss of entitlement during 1991-2000
- check termination codes on Denominator or SMEC files (PART_A_TERM_CD and PART_B_TERM_CD)
- Deceased during 1991-2000
- Non payment of premium
- Voluntary withdrawal
- Other termination
- CMS record keeping inconsistencies

## No Denominator Record

- Lack of denominator record can affect your analytic sample – why?
- Can’t determine managed care enrollment
- In general, managed care enrollees are excluded from sample (more on this to come)

## Denominator recordbut no claims data

- Entitled to Medicare but not utilizing Medicare services during 1991-2000
- Entitled to Medicare but Medicare services being used are not reimbursable claims
- Note:
- Small fraction of linked participants may have claims data but no associated Denominator record
- Some Medicare beneficiaries only enrolled in Part A
- CMS record keeping inconsistencies

## Managed Care Enrollment

- Medicare does not receive claims for beneficiaries enrolled in managed care plans (HMO)
- Do not have complete information on payments or services received
- Could miss health events that are being counted based upon submitted claims
- Complex issue. See ResDAC Technical brief at _[http://www.resdac.umn.edu/Tools/TBs/TN-009.asp](http://www.resdac.umn.edu/Tools/TBs/TN-009.asp)_

## Managed Care Enrollment

- Studies on reimbursements/charges
- Option may be to exclude those with any managed care enrollment because you don’t have complete information on payments or services received
- Studies on health outcomes/events
- Option may be to exclude those with any managed care enrollment because you could miss events
- Option may be to censor observations at time of first HMO enrollment
- Other methods for addressing HMO enrollment possible depending upon research question

## Services not covered in Medicare 1991-2000 files

- Out-patient prescription drugs
- Routine physical and dental exams
- Dentures
- Eye glasses
- Out-of-pocket expenses for Medicare beneficiaries (e.g. deductibles, coinsurance)

## Final Tips

- Read relevant documentation !!!
- Survey file layouts & detailed notes
- Linkage methodology reports
- Analytic guidelines
- Consult basic program information
- CMS – _[http://](http://www.cms.gov/)__[www.cms.gov](http://www.cms.gov/)_
- ResDAC – _[http://](http://www.resdac.umn.edu/)__[www.resdac.umn.edu](http://www.resdac.umn.edu/)_

## Final Tips

- Determine NCHS public-use files needed
- Determine RDC linked files needed
- Determine feasibility of research question based upon successfully linked respondents

## What is Feasibility Study Data?

- Public-use data indicating whether respondent was linked to Medicare data and whether there is a record on the various Medicare files
- Match status (CMS_MATCH)
- 1 = Linked
- 2 = Not linked
- 3 = Ineligible
- 80 variables indicating which of the specific Medicare files and for which of the 10 years of Medicare data data is available

## Feasibility study data are in ascii format and are survey specific. Feasibility data can be downloaded from:http://www.cdc.gov/nchs/r&d/nchs_datalinkage/data_linkage_cms.htm

**Feasibility study data are in ascii format and are survey specific. ****Feasibility data can be downloaded from:**_**[http://www.cdc.gov/nchs/r&d/nchs_datalinkage/data_linkage_cms.htm](http://www.cdc.gov/nchs/r&d/nchs_datalinkage/data_linkage_cms.htm)**_

## Restricted Data Access Methods 

- NCHS RDC, Hyattsville, MD
- On site
- Remote access
- Staff assisted, i.e. on-site programming for remote researchers
- Census RDC sites (9 locations)
- Restricted data files remain in RDC and output is inspected for disclosure violations

## Future Linkage Activities

- Continue Medicare Linkage
- Periodicity of linkages is outside NCHS control
- Current agreement includes Medicare Part D
- Medicaid
- Linkage of 1999-2004 Medicaid enrollment and claims data linked to 1999-2004 NHIS and NHANES

## It’s too complicated???What to do????

- Review documentation
- _[http://www.cdc.gov/nchs/r&d/nchs_datalinkage/data_linkage_cms.htm](http://www.cdc.gov/nchs/r&d/nchs_datalinkage/data_linkage_cms.htm)_
- Contact ResDAC – _[http://](http://www.resdac.umn.edu/)__[www.resdac.umn.edu](http://www.resdac.umn.edu/)__[/ ](http://www.resdac.umn.edu/)_
- Free assistance in obtaining and using CMS data for research
- Workshops and presentations
- Statistics and other research resources