A case-control study of HIV infection among incarcerated female drug users: impact of sharing needles and having drug-using sexual partners

Background/purpose: Taiwan experienced a rapid surge in human immunodeficiency virus (HIV) among injection drug users (IDUs) from 2003 to 2005. The male-to-female ratio of HIV cases decreased from 20:1 in 2003 to 6:1 in 2006. This change is primarily due to increasing numbers of female injection drug users in Taiwan. Our primary objective was to identify the risk factors associated with HIV infection among incarcerated female drug users.

Methods: A case-control design involved recruitment of all eligible HIV-infected female inmates from all 24 prisons in Taiwan from November to December, 2007. Eligible HIV seronegative controls were chosen within the same prison and matched to the cases by age (within 3 years) and by history of illicit drug use. A subsample of these matches was randomly selected since there were many more eligible controls than HIV-infected cases. An anonymous self-administered questionnaire was completed with assistance from trained research assistants.

Results: A total of 114 cases and 149 control participants were recruited, with a response rate of 82% and 54%. Injectable heroin use was significantly greater (p = 0.02) among HIV-infected cases (93.0%) than un-infected controls (84.6%). Compared to seronegative controls, HIV-infected cases were more likely to share drug paraphernalia and have drug-using sexual partners. Multiple logistic regression analysis revealed that the number of imprisonments (between 2-5 times; OR = 5.23), sharing mainly dilutes (OR= 63.47), and sharing dilutes concurrently with needles (OR= 127.33) significantly predicted HIV seroconversion, after controlling for age and years of education.

Conclusion: Sharing needles/dilutes and practicing unsafe intercourse with drug-using sexual partners places female drug users at considerable risk.