Objective: To assess the effect of oral and injectable contraceptive use compared to nonhormonal contraceptive use on HIV acquisition among Southern African women enrolled in a microbicide trial.
Study design: This is a prospective cohort study using data from women enrolled in HIV Prevention Trials Network protocol 035. At each quarterly visit, participants were interviewed about self-reported contraceptive use and sexual behaviors and underwent HIV testing. Cox proportional hazards regression was used to assess the effect of injectable and oral hormonal contraceptive use on HIV acquisition.
Results: The analysis included 2830 participants, of whom 106 became HIV infected (4.07 per 100 person-years). At baseline, 1546 (51%) participants reported using injectable contraceptives and 595 (21%) reported using oral contraceptives. HIV incidence among injectable, oral and nonhormonal contraceptive method users was 4.72, 2.68 and 3.83 per 100 person-years, respectively. Injectable contraceptive use was associated with a nonstatistically significant increased risk of HIV acquisition [adjusted hazard ratio (aHR)=1.17; 95% confidence interval (CI) 0.70, 1.96], while oral contraceptive use was associated with a nonstatistically significant decreased risk of HIV acquisition (aHR=0.76; 95% CI 0.37,1.55).
Conclusion: In this secondary analysis of randomized trial data, a marginal, but nonstatistically significant, increase in HIV risk among women using injectable hormonal contraceptives was observed. No increased HIV risk was observed among women using oral contraceptives. Our findings support the World Health Organization's recommendation that women at high risk for acquiring HIV, including those using progestogen-only injectable contraception, should be strongly advised to always use condoms and other HIV prevention measures.
Implications: Among Southern African women participating in an HIV prevention trial, women using injectable hormonal contraceptives had a modest increased risk of HIV acquisition; however, this association was not statistically significant. Continued research on the relationship between widely used hormonal contraceptive methods and HIV acquisition is essential.
Keywords: HIV infection; Hormonal contraception; Injectables; Oral contraceptive pills; Southern Africa; Women.
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