3,4-Methylenedioxymethamphetamine (MDMA; Ecstasy) Use and Transitions to Injection Drug Use Among Street-Involved Youth

Background: Despite the popularity of MDMA (ecstasy) among young people across North America and Europe, MDMA is rarely explored in studies of young people at highrisk of injecting drugs. We conducted a study among street-involved youth who use illicit drugs in Vancouver, Canada to understand if use of MDMA is associated with initiation of injection drugs. Methods: We followed injection-naïve participants in the At-Risk Youth Study (ARYS), an ongoing prospective cohort of street-involved youth who use illicit drugs aged 14-26. Bivariate and multivariate extended Cox models with time-updated variables were used to examine the association between MDMA use and initiation of injection drug use between September 2005 to May 2015. Results: Among 483 youth, 306 (63.4%) had a history of MDMA use and 218 (45.1%) had used MDMA in the previous six months at baseline. A total of 105 (21.7%) youth initiated injection drug use over the 10-year period, yielding an incidence density of 8.51 (95% Confidence Interval [CI]: 6.96 – 10.30) per 100 person-years. MDMA use was not significantly associated with initiating injection drugs at the bivariate- (Hazard Ratio: 0.93; 95% CI: 0.61 – 1.42) or multivariate- (Adjusted Hazard Ratio: 0.88; 95% CI: 0.57- 1.35) level after adjusting for unemployment, homelessness, and crystal methamphetamine use. Conclusions: Amid ongoing frequent use of MDMA among some young people in North America, we did not observe an elevated risk of injection initiation among those who used MDMA in this cohort of street-involved youth.