Abstract
Reliance on self-report of alcohol and drug use behavior is typical among studies of substance abusers. Few studies have compared different instruments assessing frequency of drug use over long periods of time to compare findings and determine if the pattern of use is shown to be similar across measures. In this study, the UCLA Natural History Interview (NHI) and the Addiction Severity Index (ASI) were administered at three annual follow-up periods (N = 301). The temporal pattern of the trajectories of days of use assessed by the ASI and NHI are comparable (in terms of both slope and intercept) for alcohol, heroin, cocaine, methamphetamine, and marijuana use. Some discrepancies appear to arise from differences in terminology among the instruments. However, the patterns of drug use were consistent across instruments, supporting their reliability for longitudinal examination of self-reported drug use.