The validity of self-reported cocaine use in two groups of cocaine abusers

To evaluate the validity of 2 self-report methods for estimating cocaine us e, Timeline Follow-Back (TLFB) and weekly calendar reports from 65 patients with a cocaine use disorder were compared with urine drug test results. Th e TLFB showed fair to moderate validity, and the weekly calendar showed mod erate to high validity in measuring the frequency of cocaine use. Similar r esults were obtained when the self-report measures were used to time specif ic cocaine use episodes. In addition to evidence for superiority of the wee kly calendar, the validity of self-reports was inversely related to the per centage of positive urine test results. Furthermore, there was some evidenc e that validity increased as the time window over which the comparisons wer e drawn increased. Given the central role of self-reports in the clinical a nd research evaluation of drug use, factors affecting their validity warran t further investigation.