Tranquilizer misuse among active cocaine users: Predictors of initiation.

ABSTRACT

INTRODUCTION AND AIMS: Tranquilizer use is associated with negative health outcomes among people who use drugs. This paper aims to estimate the incidence rate (initiation) and identify predictors of tranquilizer misuse (TM) among cocaine users. DESIGN AND METHODS: A prospective cohort study was conducted in Montreal, Canada. Interviewer-administered questionnaires were carried out at 3-month intervals. Initiation was defined as misusing a tranquilizer for the first time during follow-up. 'Lasting-initiation', defined as reporting TM at the next visit following first use, was also examined. Cox proportional hazard regression analyses were carried out to assess predictors of initiation to TM. RESULTS: Among the 245 participants who were eligible for the initiation analyses, 123 started TM during follow-up for an incidence rate of 40.49 per 100 person-years (95% confidence interval, CI 33.80-48.15). Of the 123 initiates, 35.7% were still using at the interview following initiation for an incidence rate of 14.70 per 100 person-years (95% CI 10.82-19.56). Multivariate models showed that independent predictors of initiation and 'lasting initiation' were identical as having had a criminal activity as the main source of income, having been recently in treatment for a substance use disorder (SUD) and reporting non-medical use of prescription opioids. DISCUSSION AND CONCLUSIONS: The incidence rate of TM initiation was high among a sample of cocaine users. Initiation was predicted by a problematic drug use pattern involving polydrug use, involvement in the street economy and having been in treatment for a SUD. These findings have implications for prevention and harm reduction strategies.