Rates of sexually transmitted infections (STI) and unplanned pregnancy are high among youth. While the intersection between drug and alcohol use and unprotected sex is well recognized, few studies have examined the relationship between substance use patterns and unprotected sex among high risk-populations such as street-involved youth.


Data were derived from the At-Risk Youth Study (ARYS), a prospective cohort of street-involved youth from Vancouver, Canada. Generalized estimating equations (GEE) were used to examine substance use patterns that were independently associated with unprotected sex, defined as (vaginal or anal) sexual intercourse without consistent condom use.


Between September 2005 and May 2013, 1,026 youth were recruited into the ARYS cohort and 75% (n = 766) reported engaging in recent unprotected sex at some point during the study period. In a multivariable analysis, female gender (adjusted odds ratio [AOR] = 1.46, 95% confidence interval [CI]: 1.18-1.81), Caucasian ancestry (AOR = 1.38, 95% CI: 1.13-1.68), being in a stable relationship (AOR = 4.64, 95% CI: 3.82-5.65), having multiple sex partners (AOR = 2.60, 95% CI: 2.18-3.10) and the following substance use patterns were all independently associated with recent unprotected sex: injection or non-injection crystal methamphetamine use (AOR = 1.21, 95% CI: 1.03-1.43), injection or non-injection cocaine use (AOR = 1.20, 95% CI: 1.02-1.41), marijuana use (AOR = 1.23, 95% CI: 1.02-1.49), ecstasy use (AOR = 1.23, 95% CI: 1.01-1.48) and alcohol use (AOR = 1.31, 95% CI: 1.11-1.55) (all p < 0.05).


Unprotected sex was prevalent among street-involved youth in this setting, and independently associated with female gender and a wide range of substance use patterns. Evidence-based and gender-informed sexual health interventions are needed in addition to increased access to youth-centered addiction treatment services. STI testing and linkages to healthcare professionals remain important priorities for street-involved youth, and should be integrated across all health and social services.