Codes and Frequencies
For persons age 18+ included in the NHIS during survey years 1994-1998 who provided sufficient data for linking (MORTELIG and whose final vital status was judged deceased (MORTSTAT) as of December 31, 2006, MORTCMS indicates that the source of the mortality data was the Centers for Medicaid and Medicare Services (CMS), rather than the National Death Index (NDI). Physicians and hospitals treating Medicaid and Medicare enrollees must report a preliminary assessment of the patient's cause of death (no further documentation is required). This creates a death record in the CMS database.
The National Health Interview Survey Linked Mortality Files Analytic Guidelines state, "The primary determination of mortality for eligible participants is based upon matching survey records to the NDI. However, NCHS also relies on additional sources of information to determine the mortality status of a survey participant. Other sources of mortality include the Social Security Administration, the Centers for Medicare and Medicaid Services, and death certificates. If a source of mortality, other than a NDI record was available, the participant was considered deceased."
Other variables identifying the sources of mortality information are:
- MORTSSA (Mortality status obtained from Social Security Administration)
- MORTNDI (Mortality match with National Death Index)
The NDI is a central database that collects and stores death records from State vital statistics offices. As noted above, mortality ascertainment is first attempted through a probabilistic match between NHIS and NDI death certificate records, if there is sufficient identifying data (Social Security number, date of birth, and name). For additional information, see the technical documents from NCHS on the creation and analysis of the NHIS Linked Mortality Files.
For other mortality variables included in the IPUMS NHIS, please refer to the MORTSTAT variable description.
MORTCMS is only available between 1994-1998. As NCHS documentation states, "For the NHIS years 1994-1998, a code 1 indicates that mortality status was obtained from the Centers for Medicare and Medicaid Services (CMS). For the NHIS years 1986-1993 and 1999-[forward], CMS is not a source of mortality information. For these years, this variable is coded as not applicable."
- 1994-1998: Persons age 18+ eligible for mortality follow-up and assumed dead.
- 1994-1998 : MORTWT