Key points
- The National Center for Health Statistics (NCHS) Data Linkage Program links NCHS survey data with data from the National Death Index (NDI).
- Linking NCHS data with NDI death certificate data enables researchers to conduct outcome studies to learn about how different health factors relate to mortality (death).
- Find details about the linked data, linkage methods, and analysis considerations.
Overview
The National Center for Health Statistics (NCHS) Data Linkage Program connects NCHS survey data with data from other agencies. NCHS links data from its surveys with death certificate records from the National Death Index (NDI).
Linking survey participant data with NDI mortality (death) data allows researchers to conduct outcome studies. Outcome studies investigate the connection between health factors and death.
The linked mortality files (LMFs) have been updated with mortality follow-up data through December 31, 2019.
NCHS surveys linked to NDI mortality data
- National Health Interview Survey (NHIS): 1986–2018
- National Health and Nutrition Examination Surveys (NHANES): 1999–2018
- Third National Health and Nutrition Examination Survey (NHANES III)
- NHANES I Epidemiologic Follow-up Study (NHEFS)
- National Nursing Home Surveys (NNHS): 1985, 1995, 1997, 2004
Linked mortality data bibliography
- Linked mortality file citation list (rev. 05/12/2025)
2019 public-use
Linked public-use files contain a limited set of mortality (death) data for adults. Public-use LMFs are available for—
- NHIS (1986–2018)
- NHANES (1999–2018)
- NHANES III (1999–2018)
Some information in the public-use versions was changed to keep participants' identities safe. For certain records, the follow-up time or underlying cause of death were substituted with synthetic values. Information about whether a person is alive or dead was not changed.
- Public-use 2019 LMF file description (05/2022)
- Public-use 2019 LMF data dictionary (04/28/2022)
- Software programs:
2019 restricted-use
Restricted-use files contain information about both adults and children. Data were not altered for the restricted-use files.
Restricted-use LMFs can be accessed only through the NCHS Research Data Center (RDC) network for approved projects. Researchers cannot use public-use and restricted-use LMFs together in the RDC.
Restricted-use data dictionaries
- Mortality variables (07/07/2021)
- Death certificate and NDI match variables (07/07/2021)