Club drugs and alcohol abuse are prevalent among methadone maintenance treatment (MMT) patients. However, little is known about the association between these abuse and treatment outcomes among MMT patients. The aim of this study was to examine the prevalence of club drugs and alcohol abuse among MMT patients and to investigate the associations between these abuse and treatment outcomes - dropout and poor adherence. In this one-year cohort study conducting in Guangzhou, China, data including background characteristics, club drugs use in the last six months, alcohol use history and treatment-related information was collected. Cox regression analyses and log-binomial regression analyses were applied to identify the associations between these abuse and dropout and poor adherence, respectively. Thirty-seven participants (9.2%) admitted to the use of at least one type of club drugs in the last six months and 88 (21.9%) were identified as alcohol abusers. Of all participants, 21.0% had dropped out of treatment and 27.7% exhibited poor adherence during the study period. Adjusting for significant background variables, use of at least one type of club drugs [hazards ratio (HR) = 1.90, 95% confidence interval (CI) = 1.01-3.56] and use of methamphetamine in the last six months (HR = 2.26, 95% CI = 1.15-4.43) significantly predicted dropout. Frequency of having six or more drinks on one drinking occasion when drinking [relative risk (RR) = 1.87, 95% CI = 1.16-2.95] significantly predicted poor adherence. Our findings indicated that club drugs and alcohol abuse predicted dropout and poor adherence among MMT patients. Early identification and intervention for the abuse should be taken into consideration when developing interventions tailored to improve treatment outcomes among MMT patients.
Keywords: Methadone maintenance treatment; adherence; alcohol; club drugs; dropout.