Sex-specific determinants of HIV infection among injection drug users in Montreal

Sex-specific issues have not been extensively addressed in studies of HIV prevalence, despite the strong implications of differences between men and women in the risk of HIV transmission. The objective of this study was to examine sex-specific behaviours associated with HIV infection among injection drug users in Montreal.

A total of 2741 active drug users (2209 [80.6%] men) were recruited between 1988 and 1998. Information was sought on sociodemographic characteristics, drug-related behaviour and sexual behaviour, and participants were tested for HIV antibodies. Sex-specific independent predictors of HIV prevalence were assessed by stepwise logistic regression.

The overall prevalence of HIV among study subjects was 11.1%; the prevalence was 12.0% among men and 7.5% among women. In multivariate models, a history of sharing syringes with a known seropositive partner (odds ratio [OR] for men 2.44, 95% confidence interval [CI] 1.72-3.46; OR for women 3.03, 95% CI 1.29-7.13) and of sharing syringes in the past 6 months (OR for men 0.61, 95% CI 0.44-0.85; OR for women 0.32, 95% CI 0.14-0.73) were independently associated with HIV infection. Other variables associated with HIV infection were homosexual or bisexual orientation, cocaine rather than heroin as drug of choice, frequency of injection drug use, and obtaining needles at a pharmacy or through needle exchange programs (for men only) and obtaining needles at shooting galleries and being out of treatment (for women only).

These results support the hypothesis that risk factors for HIV seropositivity differ between men and women. These sex-related differences should be taken into account in the development of preventive and clinical interventions.