TEST OF THE NATIONAL DEATH INDEX AND EQUIFAX NATIONWIDE DEATH SEARCH

The authors compared the ability of the National Death Index and the E quifax Nationwide Death Search to ascertain deaths of participants in the Nurses' Health Study. Each service was sent information on 197 par ticipants aged 60-68 years in 1989 whose deaths were reported by kin o r postal authorities and 1,997 participants of the same age who were k nown to be alive. Neither service was aware of the authors' informatio n regarding participants' vital status. The sensitivity of the Nationa l Death Index was 98 percent and that of Equifax was 79 percent. Sensi tivity was similar for women aged 65-68 years; however, for women aged 61-64 years, the sensitivity of the National Death Index was 97.7 per cent compared with 60.2 percent for Equifax. The specificity of both s ervices was approximately 100 percent. The contrast between the source s of these databases and the matching algorithms they employ has impli cations for researchers and for those planning health data systems.