Gender influences on initiation of injecting drug use

Background and objectives: Gender differences in illicit drug use patterns and related harms (e.g. HIV infection) are becoming increasingly recognized. However, little research has examined gender differences in risk factors for initiation into injecting drug use. We undertook this study to examine the relationship between gender and risk of injection initiation among street-involved youth and to determine whether risk factors for initiation differed between genders. Methods: From September 2005 to November 2011, youth were enrolled into the At-Risk Youth Study, a cohort of street-involved youth aged 14-26 in Vancouver, Canada. Cox regression analyses were used to assess variables associated with injection initiation and stratified analyses considered risk factors for injection initiation among male and female participants separately. Results: Among 422 street-involved youth, 133 (32.5%) were female, and 77 individuals initiated injection over study follow-up. Although rates of injection initiation were similar between male and female youth (p=0.531), stratified analyses demonstrated that, among male youth, risk factors for injection initiation included sex work (Adjusted Hazard Ratio [AHR]=4.74, 95% Confidence Intervals [CI]: 1.45-15.5) and residence within the city's drug use epicenter (AHR=1.95, 95% CI: 1.12-3.41), whereas among female youth, non-injection crystal methamphetamine use (AHR=4.63, 95% CI: 1.89-11.35) was positively associated with subsequent injection initiation. Conclusion: Although rates of initiation into injecting drug use were similar for male and female street youth, the risk factors for initiation were distinct. These findings suggest a possible benefit of uniquely tailoring prevention efforts to high-risk males and females.