NHANES and CMS Data Linkage

Purpose

This module describes the linkage process of the National Health and Nutrition Examination Survey (NHANES) to two major sources of data from Centers for Medicare & Medicaid Services (CMS): administrative records from the Medicare and Medicaid programs.

Task: Describe how the CMS Files are Linked to NHANES Files

This task will describe how National Health and Nutrition Examination Survey (NHANES) data are linked to the Centers for Medicare & Medicaid Services (CMS) Medicare and Medicaid data and describe linkage eligibility for survey respondents.

The linkage of NHANES participants to their Centers for Medicare & Medicaid Services (CMS) records was performed under an interagency agreement between the National Center for Health Statistics (NCHS) and CMS and is not the responsibility of the researchers using the data. The linkage was conducted for all NHANES participants who provided consent as well as the necessary personally identifiable information (PII), such as date of birth and SSN or Medicare Health Insurance Claim (HIC) number to enable person-level linkage. These survey participants were considered linkage eligible and their data were uploaded to the CMS Virtual Research Data Center (VRDC) to match to the CMS Medicare and Medicaid administrative records.

Information: The term eligible is being used to indicate linkage eligibility, not eligibility for Medicare or Medicaid benefits. Match rate tables, indicating linkage eligibility, can be found in the Resources section below.

Resources

Data for survey participants who were considered linkage eligible were uploaded to the CMS VRDC to match to the Medicare administrative records. The range of years of NHANES and Medicare data that are linked are described in Course 1, Module 4, Task 2 “Years of NHANES-CMS Linked Data.” The NHANES file used for matching did not contain the NHANES participants’ public-use ID (SEQN). CMS extracted data from each of the Medicare files for the records that were successfully matched to the NHANES participants. Non-matches include those participants eligible for linkage that were not enrolled in Medicare, as well as those not successfully matched to the CMS Medicare administrative records for the specific years.

A more thorough discussion on the linkage process for Medicare may be found in the report NCHS-CMS Medicare Matching Methodology and Analytic Considerations. A link to the report is located in the Resources section.

Information: The term eligible is being used to indicate linkage eligibility, not eligibility for Medicare benefits.

Resources

Data for the survey participants who were considered linkage eligible were uploaded to the CMS VRDC to match to the Medicaid administrative records for the specific years of interest. The range of years of NHANES and Medicaid data that are linked is described in Course 1, Module 4, Task 2 “Years of NHANES-CMS Linked Data.” The file used for matching did not contain the NHANES participants’ public-use ID (SEQN). CMS extracted data from each of the Medicaid files that were successfully matched to the NHANES participants.

A more thorough discussion on the linkage process for Medicaid may be found in the NCHS-CMS Medicaid Matching Methodology and Analytic Considerations. A link to the report is located in the Resources section.

Information: The term eligible is being used to indicate linkage eligibility, not eligibility for Medicaid benefits.