Codes and Frequencies
For persons age 18+ included in the NHIS during survey years 1986 to 2014 who provided sufficient data for linking (MORTELIG) and whose final vital status was judged deceased (MORTSTAT), MORTUCODLD reports the leading underlying cause of death. This information was determined by NCHS based on probabilistic matches of survey participants' NHIS records to National Death Index (NDI) records and aggregated into 10 cause of death categories. For survey respondents in the 2005 or later surveys and decedents who died after December 2006, MORTUCODLD is the most detailed information available on the linked NHIS-NDI public use files about underlying cause of death. For access to the detailed cause of death codes available on the linked NHIS-NDI restricted access files, see documentation on the restricted version of the NHIS Linked Mortality Files.
MORTUCODLD is a recode created by NCHS to classify underlying cause of death across 113 categories. Deaths that occurred prior to 1999 are coded based on the 9th revision of the International Statistical Classification of Diseases, Injuries, and Causes of Death (ICD-9). Deaths that occurred from 1999 forward were coded based on the 10th revision of the International Statistical Classification of Diseases, Injuries, and Causes of Death (ICD-10).
Because adult survey participants who provided insufficient data for linking may differ from those who provided enough data for linking, ignoring the ineligible adult respondents (IPUMS NHIS code 3 in MORTELIG) could lead to biased mortality analysis. To correct this bias, NCHS developed eligibility-adjusted weights: MORTWT, available for 1986-2014, for use with variables from the NHIS person files, and MORTWTSA, available for 1997-2014, for use with variables from the sample adult files. When analyzing NHIS variables from the person files in conjunction with MORTUCODLD, users should employ MORTWT (rather than the standard person weight, PERWEIGHT). When analyzing variables from the sample adult files in conjunction with MORTUCODLD, users should employ MORTWTSA (rather than the standard sample weight, SAMPWEIGHT).
For further information on the NDI and the creation of the mortality variables, see the variable description for MORTELIG and the technical documents from NCHS on the creation and analysis of the NHIS Linked Mortality Files.
For other mortality variables included in IPUMS NHIS, refer to the MORTSTAT variable description.
MORTUCODLD is largely comparable over time. As noted above, deaths occurring prior to 1999 are based on the 9th revision of the International Statistical Classification of Diseases, Injuries, and Causes of Death (ICD-9); deaths occurring from 1999 forward are coded based on the 10th revision (ICD-10).
- 1986-2014: All persons age 18+ eligible for mortality follow-up, assumed dead, and whose assumed cause of death was not unknown.
- 1986-2014 : MORTWT