A 2-STAGE PROTOCOL FOR VERIFYING VITAL STATUS IN LARGE HISTORICAL COHORT STUDIES

When access to the Social Security Administration's Master Death Claim File runs restricted in the mid-1980s, researchers were left with no time-and cost-effective protocol for verifying the vital status of lar ge historical cohorts. A two-stage tracing protocol was designed to ov ercome this restriction, Stage I relies on national-scale sources to f ocus on the complete and accurate identification of deaths among perso ns unconfirmed as alive and assumes that persons not identified as dec eased are alive, Stage II tests the ''alive'' assumption by extensivel y tracing a random sample of cohort members with unconfirmed vital sta tus. Stage II provides unbiased estimates of the proportion of deaths among the assumed ''alives'' in the cohort (misclassification rate) an d the proportion of persons untraceable in the total coho?it, This pap er describes our two-stage protocol and an application to a large, ong oing occupational cohort study.