Accuracy of on-line databases in determining vital status.

Ascertainment of vital status is important for epidemiological and clinical trial research. Two free databases based on the Social Security Administration Death Master File have become available on the Internet. The accuracy of these databases is unknown. A cohort of 124 patients known to be dead and a cohort of 203 patients not known to be dead were identified. The on-line databases were searched with both of these cohorts following a specific search algorithm. The results for both on-line databases were identical. The optimal algorithm had a sensitivity of 0.82 (95% confidence interval 0.74-0.89) for identification of deaths. The sensitivity excluding deaths that occurred during the first year of life (n = 118) was 0.86 (95% CI 0.79-0.92). The specificity was 1.00. This study found that free and convenient on-line databases based on the Social Security Administration Death Master File can be useful in the accurate ascertainment of vital status.