On the Value of Measuring Recent Drug Use by Self-Reports and Urinalysis in Clinical Trials

<i>Background:</i> Valid measurement of drug use in patients enrolled in clinical trials that treat substance use disorder is vital to determine the trial's outcome. Self-reports are often used but their validity has been studied with mixed results. Urinalysis may sometimes be employed as an alternative or supplement to self-reports. <i>Objectives:</i> This study examined how estimating drug use by either method would affect the results from a randomized clinical trial conducted in a methadone treatment program. At the initial Baseline interview and four follow-up interviews, participants were asked about their drug use history and provided a urine specimen for drug testing. <i>Results:</i> In most cases, the urinalyses detected more drugs than the patients had reported using. A major exception was heroin, whose use was an eligibility criterion for enrollment in the study and methadone treatment. <i>Conclusions:</i> The patients' self-reports would have led us to conclude that the use of heroin and fentanyl had declined from the initial Baseline interview to the final follow-up interview, while the urinalysis results indicated no change in exposure to heroin and an increase in exposure to fentanyl. Clinical trials would be well served to employ the use of biological tests in addition to self-reports to measure recent drug use and to accurately estimate the efficacy of the experimental protocols and patients' exposure to drugs.