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 1986-2009, for use with variables from the NHIS person files, and MORTWTSA, available for 1997-2009, for use with variables from the sample adult files. When analyzing NHIS variables from the person files in conjunction with mortality variables, users should employ MORTWT (rather than the standard person weight, PERWEIGHT). When analyzing variables from the sample adult files in conjunction with mortality variables, users should employ MORTWTSA (rather than the standard sample weight, SAMPWEIGHT).

MORTHIPFX was one of three multiple cause of death flags that indicate whether specific health conditions were listed as contributing causes of death (in addition to the underlying cause of death). MORTDIAB indicates whether diabetes was listed as a contributing cause of death; MORTHYPR indicates whether hypertension was listed as a contributing cause of death.

For other mortality variables included in IPUMS NHIS, please refer to the MORTSTAT variable description.

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.