The accuracy of ascertaining vital status in a historical cohort study of synthetic textiles workers using computerized record linkage to the Canadian Mortality Data Base.

Vital status of a cohort of 10,211 Quebec, synthetic textiles workers was ascertained through a probabilistic record linkage to the Canadian Mortality Data Base (CMDB); 5,033 of these workers were also traced using other sources. There was agreement in the vital status of all but 60 of the subjects traced jointly through the CMDB and the alternate sources. 41 subjects were declared 'deceased' from the CMDB but 'alive' from the alternate sources; it is likely that these subjects were indeed deceased. 19 subjects, declared 'deceased' with a fair degree of certainty from the alternate sources, were not identified from the computer search of the CMDB; 17 were found manually on the microfiche death records and two died outside of Canada. The probability of identifying deceased and living subjects from the CMDB was therefore estimated to be 98.2% (95% confidence interval: 97.5-98.7%) and about 100%, respectively. Estimates of cost are also presented, and it is concluded that use of the CMDB is the method of choice for tracing moderate to large cohorts.