Long-term follow-up of participants in clinical studies.

We evaluated a multistep protocol to locate and ascertain data from 708 subjects who participated in clinical studies at our medical center up to 27 years ago. The protocol involved computerized and manual chart audits, introductory letters, internet searches, death registries, and a commercial person locator. We were able to ascertain vital status on 596 (84%) of study participants. Moreover, of the 475 persons known to be alive, 426 (90%) returned questionnaires and 275 (58%) completed physical examination and laboratory studies in our Clinical Research Center. The relatively modest cost of the protocol ($53,426) suggests that it is a reasonable strategy to test hypotheses involving long-term outcomes among well-characterized cohorts. The fact that the protocol can be easily implemented in most sites should encourage investigators to use these strategies to conduct similar studies.