Plan and operation of the NHANES I Epidemiologic Followup Study, 1992

OBJECTIVES: The NHANES I Epidemiologic Followup Study (NHEFS) is a longitudinal study that uses as its baseline those adult persons 25-74 years of age who were examined in the first National Health and Nutrition Examination Survey (NHANES I). NHEFS was designed to investigate the association between factors measured at baseline and the development of specific health conditions. The three major objectives of NHEFS are to study morbidity and mortality associated with suspected risk factors, changes over time in participants' characteristics, and the natural history of chronic disease and functional impairments. METHODS: Tracing and data collection in the 1992 Followup were undertaken for the 11,195 subjects who were not known to be deceased in the previous surveys. No additional information was collected in the 1992 NHEFS for the 3,212 subjects who were known to be deceased before the 1992 NHEFS data collection period. RESULTS: By the end of the 1992 NHEFS survey period, 90.0 percent of the 11,195 subjects in the 1992 Followup cohort had been successfully traced. Interviews were conducted for 9,281 subjects. An interview was conducted for 8,151 of the 8,687 surviving subjects; 551 interviews were administered to a proxy respondent because the subject was incapacitated. A proxy interview was conducted for 1,130 of the 1,392 decedents identified in the 1992 NHEFS. In addition, 10,535 facility stay records were collected for 4,162 subjects reporting overnight facility stays. Death certificates were obtained for 1,374 of the 1,392 subjects who were identified as deceased since last contact. Approximately 32 percent of the NHEFS cohort is known to be deceased with a death certificate available for 98 percent of the 4,604 NHEFS decedents.