Hormonal Contraception and Vaginal Infections Among Couples Who Are Human Immunodeficiency Virus Serodiscordant in Lusaka, Zambia

OBJECTIVE: To examine the relationship between hormonal contraception and vaginal infections with bacterial vaginosis, vaginal candidiasis, or trichomoniasis. METHODS: Couples who were human immunodeficiency virus (HIV) serodiscordant in Zambia were enrolled in a longitudinal cohort study. From 1994 to 2002, both partners were seen quarterly and received physical exams including genital examinations. Separate rates for three outcome infections of interest (bacterial vaginosis, vaginal candidiasis, and trichomoniasis) were calculated. Bivariate associations between baseline and time-varying covariates and outcome infections of interest were evaluated using unadjusted Anderson-Gill survival models. Adjusted hazard ratios (aHRs) were generated using multivariable Anderson-Gill survival models that included demographic and clinical factors associated with both hormonal contraceptive use and each infection of interest. RESULTS: There were 1,558 cases of bacterial vaginosis, 1,529 cases of vaginal candidiasis, and 574 cases of trichomoniasis over 2,143 person-years of observation. Depot medroxyprogesterone acetate (DMPA) users had significantly lower rates of trichomoniasis and bacterial vaginosis. In adjusted models, DMPA was protective for bacterial vaginosis (aHR=0.72; 95% CI 0.54-0.95), candidiasis (aHR 0.75, 95% CI 0.57-1.00) and trichomoniasis (aHR=0.43, 95% CI 0.25-0.74). Oral contraceptive pills were protective for candidiasis (aHR=0.79, 95% CI 0.65-0.97). CONCLUSION: We confirm that DMPA use was associated with reduced rates of the three most common causes of vaginitis, and oral contraceptive pill use was associated with reduced rates of candidiasis among women in couples who were HIV discordant.