Effectiveness of the National Death Index for establishing the vital status of older women in the Australian Longitudinal Study on Women's Health

Objective: To assess the effectiveness of the National Death Index (NDI) in identifying participants in the oldest cohort of the Australian Longitudinal Study on Women's Health (ALSWH) who had died between 1996 and 1998. Methods: identifying information for each woman was matched with the NDI using a probabilistic algorithm and clerical review. Differences in full name, date of birth, State of residence and date of last contact were used to assess the probability of a true match. Results: NDI identified 410 matches of death records for 409 women; 386 were categorised as true matches and 23 were doubtful matches. Responses to the follow-up survey confirmed that for six of the doubtful matches the women had died, 16 were alive and the vital status of one woman remained unconfirmed at 30 June 1998. Twelve deaths, known to have occurred before July 1998, were not identified through NDI. The sensitivity of the NDI for identifying known deaths was 95%. Detailed identifying information, particularly the middle name, was important for accurate identification of the vital status. Conclusions: Using surname, all given names, gender, date of birth, State of residence and age at last contact as matching variables, the NDI was an effective tool for identifying women who had died. Implications: Routinely collected mortality data in the NDI are useful for the practice of epidemiology