Validity and consistency of self-reports regarding substance use in general research volunteers, including regular cannabis users and schizophrenia patients.

This study investigated the validity of self-reports of substance use in 69 low-level substance users from the general community of Perth, Australia, volunteering for electrophysiological research, between 2002 and 2003. The participants included regular cannabis users and schizophrenia patients. Self-reports of recent use (last 24 hours) highly agreed with urine screen results (kappa = 0.91). Self-reports of past use (lifetime and last 12 months) had poor-moderate consistency based on correlations among dependence (measured with SDS, FTND, SMAST, CAGE), frequency, and use duration. Therefore, under some conditions, self-reports are valid for recent use and only moderately consistent for past substance use in general research participants.