Neighborhood of residence and risk of initiation into injection drug use among street-involved youth in a Canadian setting

Background: While research has suggested that exposure to environments where drug use is prevalent may be a key determinant of drug-related risk, little is known regarding the impact of such exposure on the initiation of illicit injection drug use. We assessed whether neighborhood of residence predicted rates of injecting initiation among a cohort of street-involved youth in Vancouver, British Columbia. Methods: We followed street-involved injecting naïve youth aged 14-26 and compared rates of injecting initiation between youth residing in Vancouver's Downtown Eastside (DTES) neighborhood (the site of a large street-based illicit drug market) to those living in other parts of the city. Univariate and multivariate Cox regression analyses were employed to determine whether residence in the DTES was independently associated with increased risk of initiation of injection drug use. Results: Between September, 2005 and November, 2011, 422 injection-naïve individuals were followed, among whom 77 initiated injecting for an incidence density of injecting of 10.3 (95% confidence interval [CI] 5.0-18.8) per 100 person years. In a multivariate model, residence in the DTES was independently associated with initiating injection drug use (adjusted hazard ratio [AHR]=2.16, 95% CI: 1.33-3.52, p=0.002). Conclusions: These results suggest neighborhood of residence affects the risk of initiation into injection drug use among street-involved youth. The development of prevention interventions should target high-risk neighborhoods where risk of initiating into injecting drug use may be greatest.