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NHANES II Mortality Study (NH2MS) Public-use Data File

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The NHANES II Mortality Study (NH2MS) is a prospective cohort study that passively followed a subset of participants in the Second National Health and Nutrition Examination Survey (NHANES II).  NHANES II was conducted on a nationwide probability sample of approximately 28,000 persons 6 months through 74 years of age from the civilian, noninstitutionalized population of the United States. The survey started in February 1976 and was completed in February 1980. NHANES II included a standardized physical examination, laboratory tests, and questionnaires that covered various health-related topics. Although NHANES II provided a wealth of information on the prevalence of health conditions and risk factors, the cross-sectional nature of the original survey limits its usefulness for studying the effects of clinical, environmental, and behavioral factors on the development of specific health conditions.

The NH2MS was designed to investigate the association between factors measured at baseline and overall mortality or death from specific causes. NHANES II obtained information gathered from physical exams, laboratory tests, and interviews, whereas the NH2MS involves searching national databases containing information about mortality and causes of death. The NH2MS mortality data can be linked with the earlier baseline NHANES II data to examine the relationships between various factors and specific causes of death.

Note that the design of the NH2MS differs substantially from that of the NHANES I Epidemiologic Follow-up Study (NHEFS), a longitudinal follow-up of an earlier NHANES cohort. NHEFS was an active follow-up study in which participants were recontacted and medical records and death certificates were obtained. In contrast, the NH2MS is entirely passive, that is, participants were not recontacted nor were all death certificates obtained. Instead, mortality status was ascertained solely by computerized matching to national databases and evaluation of the resulting matches. Furthermore, no recontact is planned in the future. Instead, matching to the NDI and other national databases will continue on a periodic basis. Future waves will be released for public use on a periodic basis. One important ramification of the NH2MS design is that persons not found to be deceased are assumed alive for analytic purposes. As a result, there is a potential for misclassification of vital status. Researchers using the NH2MS data should be aware of this study limitation.

The NH2MS cohort is comprised of adults who were 30-75 years of age at the time of their NHANES II examination (n=9,252). This cohort is a subset of the persons selected to participate in NHANES II. Some participants were interviewed but not examined and only those examined were followed for mortality status. The baseline included persons between the ages of 6 months and 74 years and only adults were included in the follow-up cohort. Age at exam was used to identify participants 30 years and over for selection into the NH2MS cohort. Because several weeks could have elapsed between the interview and examination, some participants who were 74 years of age during their interview turned 75 years of age between their interview and examination. For this reason, the upper age limit for the NH2MS cohort is 75 years.

During this first wave of the study, mortality status was ascertained for the years 1976-92. Two participants were unable to be followed because of incomplete personal identifying data and are considered lost to follow-up. The 9,250 cohort members were traced in the NH2MS by searching national databases containing mortality and cause-of-death information. The length of follow-up period ranges from 12 to 16 years. Approximately 23 percent (n=2,145) of the NH2MS cohort were found to be deceased as of December 31, 1992.

Detailed information on the design, content, and operation of the 1992 NH2MS may be found in the Vital and Health Statistics Series 1, Number 38 "Plan and Operation of the NHANES II Mortality Study 1992."

This page last reviewed August 23, 2002