Cessation of Injecting and Preceding Drug Use Patterns Among a Prospective Cohort of Street-Involved Youth

Purpose: Injection drug use is prevalent among street-involved youth, but patterns of cessation are poorly described. We identified drug use patterns preceding injection cessation among street-involved youth.Methods: From September 2005 to May 2015, we collected data from the At-Risk Youth Study, a prospective cohort of street-involved youth in Vancouver, Canada, and limited the sample to actively injecting youth. The primary outcome was cessation of injecting self-reported at semiannual follow-up visits. We used Cox regression to identify drug use patterns preceding cessation.Results: Among 383 youth, 65% were male, mean age was 22.3 (SD, 2.5; range, 15-30) years, and 171 (45%) ceased injecting for 6 months or more (crude incidence density 22 per 100 person-years; 95% confidence interval [CI], 19-26). Youth who ceased were less likely to have injected daily (adjusted hazard ratio [AHR], 0.40; 95% CI, 0.28-0.56), injected heroin (AHR, 0.40; 95% CI, 0.29-0.56), or injected crystal methamphetamine (AHR, 0.43; 95% CI, 0.31-0.59) prior to cessation. Non-injection heroin use was positively associated with injection cessation (AHR, 1.52; 95 CI, 1.12-2.08). Addiction treatment was not associated with cessation. At the time of cessation, 101 (59%) youth continued to use ‘hard’ non-injection drugs such as heroin and crystal methamphetamine.Conclusions: Periods of injection cessation were common but frequently accompanied by ongoing non-injection drug use. Findings indicate that trajectories of injection drug use among youth are complex and highlight the need to further explore relationships between ongoing non-injection drug use and injection cessation.