Can you trust patient self-reports of drug use during treatment?

This study compared two frequently used measures of drug use, urine testing and self-report in a sample of subjects currently enrolled in methadone treatment for a minimum of six months. A comparison between the percentage of positive opiate urine screens and subjects' self-reported opiate use indicated that more patients self-reported opiate use (80%) than had been detected by urinalysis (57%). Similar results were found for cocaine use. We present arguments that a more inclusive method of measuring drug use during treatment should include the combination of both urinalysis and self-reports.