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

Background: Sex-specific issues have not been extensively addressed in stud ies of HIV prevalence, despite the strong implications of differences betwe en men and women in the risk of HIV transmission. The objective of this stu dy was to examine sex-specific behaviours associated with HIV infection amo ng injection drug users in Montreal. Methods: A total of 2741 active drug users (2209 [80.6%] men) were recruite d between 1988 and 1998. information was sought on sociodemographic charact eristics, drug-related behaviour and sexual behaviour, and participants wer e tested for HIV antibodies. Sex-specific independent predictors of HIV pre valence were assessed by stepwise logistic regression. Results: 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 rat io [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 fo r men 0.61, 95% CI 0.44-0.85; OR for women 0.32, 95% CI 0.14-0.73) were ind ependently associated with HIV infection. Other variables associated with H IV infection were homosexual or bisexual orientation, cocaine rather than h eroin as drug of choice, frequency of injection drug use, and obtaining nee dles at a pharmacy or through needle exchange programs (for men only) and o btaining needles at shooting galleries and being out of treatment (for wome n only). Interpretation: These results support the hypothesis that risk factors for HIV seropositivity differ between men and women. These sex-related differen ces should be taken into account in the development of preventive and clini cal interventions.