Background: The evidence from epidemiological research into whether use of hormonal contraception increases women's risk of HIV acquisition is inconsistent. We did a robust meta-analysis of existing data to provide summary estimates by hormonal contraceptive method which can be used to inform contraceptive guidelines, models, and future studies.
Methods: We updated a recent systematic review to identify and describe studies that met inclusion criteria. To ensure inclusion of more recent research, we searched PubMed for articles published after December, 2011, using the terms "hormonal contraception", "HIV/acquisition", "injectables", "progestin", and "oral contraceptive pills". We assessed statistical heterogeneity for these studies, and, when appropriate, combined point estimates by hormonal contraception formulation using random-effects models. We assessed publication bias and investigated heterogeneity through subgroup and stratified analyses according to study population and design features.
Findings: We identified 26 studies, 12 of which met inclusion criteria. There was evidence of an increase in HIV risk in the ten studies of depot medroxyprogesterone acetate (pooled hazard ratio [HR] 1·40, 95% CI 1·16-1·69). This risk was lower in the eight studies done in women in the general population (pooled HR 1·31, 95% CI 1·10-1·57). There was substantial between-study heterogeneity in secondary analyses of trials (n=7, I(2) 51·1%, 95% CI 0-79·3). Although individual study estimates suggested an increased risk, substantial heterogeneity between two studies done in women at high risk of HIV infection (I(2) 54%, 0-88·7) precluded pooling estimates. There was no evidence of an increased HIV risk in ten studies of oral contraceptive pills (pooled HR 1·00, 0·86-1·16) or five studies of norethisterone enanthate (pooled HR 1·10, 0·88-1·37).
Interpretation: Our findings show a moderate increased risk of HIV acquisition for all women using depot medroxyprogesterone acetate, with a smaller increase in risk for women in the general population. Whether the risks of HIV observed in our study would merit complete withdrawal of depot medroxyprogesterone acetate needs to be balanced against the known benefits of a highly effective contraceptive.
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