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Vaginal microbicides for preventing mother-to-child transmission of HIV infection - no evidence of an effect or evidence of no effect?
Abstract
Background. Vaginal disinfection is a simple, potentially effective strategy for reducing mother-to-child transmission (MTCT) of HIV that can be implemented in combination with antiretroviraltherapy or even in the absence of prenatal HfV testing. We systematically reviewed currently available randomised controlled trials to estimate the benefits and risks of this intervention.
Methods. We conducted an exhaustive search for published and. unpublished trials assessing the effect of vaginal microbicides on MTCT of HIV, extracted data in triplicate, assesed statistical heterogeneity between trial results, and conducted meta-analysis using Mantel-Haenszel's method.
Findings. Five potentially eligible studies were iclentified, two of which met eligibility criteria. Pooling the data shows that the effect of vaginal disinfection on the risk of MTCT of HIV relative risk (RR) 0.94, 95% confidence interval (CI) 0.71 1.25) and neonatal death (RR 1.36, 95% CI 0.32- 5.79) is uncertain. The combined data (two trials with 708 participants) had less than 80% power to detect a 30% reduction in the risk of MTCT of HIV from a baseline risk of 30%, and are compatible with a widerange of effects; from a 29% reduction to a 25% increase in risk. One trial with 108 participants, showed no evidence that adverse effects increased inmothers (RR L02, 95% CI 0.87- 1.20) and found that adverse effects decreased in neonates (RR 0.45, 95% CI 0.32 - 0.64).
Interpretation. At present there is insufficient and inconclusive evidence on the effect of vaginal microbicides on the risk of MTCT of HIV. This review identifies the need and provides the impetus for an adequately powered randomised controlled trial to assess the effect(s) of this inexpensive intervention.