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Contraceptive injections and HIV infection risk – a public health conundrum
Roger Pebody, 2013-03-10 19:00:00
The concerns about a possible increase in risk of HIV acquisition with some hormonal contraceptive methods need to be understood in the context of the substantial uncertainties in the body of evidence, and considered alongside the life-saving benefits of hormonal contraceptive use, Dr Chelsea Polis of USAID told the 20th Conference on Retroviruses and Opportunistic Infections (CROI 2013) in Atlanta last week. This “leaves us in a real public health conundrum”, she said.
The conundrum is made more difficult by the knowledge that the concerns focus on the injectable contraceptive depot medroxy progesterone acetate (DMPA, sometimes sold as Depo-Provera). While in some regions, DMPA is one of the only highly effective contraceptive methods that is accessible and acceptable, some of these regions (especially southern and eastern Africa) also have a substantial burden of HIV infection.
“The potential risk with DMPA must be balanced against risks of maternal morbidity and mortality, infant morbidity and mortality, and unsafe abortion,” Polis said. Moreover, she reminded the audience that some data suggest that pregnancy itself can raise a woman’s risk of acquiring HIV.
A number of studies show oral contraceptive pills to be safe and limited data suggest that injectable depot contraceptive NET-EN (Noristerat) is safe too.
But there are virtually no studies which can answer questions about implants, skin patches, vaginal rings and hormonal intrauterine devices.
Polis was one of the epidemiologists who took part in the systematic review which led the World Health Organisation to conclude a year ago that there is not yet sufficient evidence to advise against the use of DMPA injections. At CROI, Polis summarised the review data, which she had previously presented at the International AIDS Conference last year.
She also pointed to more recent data, which need to be taken into account when the systematic review is updated – the MDP301 study (described below), the MIRA trial, and a re-analysis of the large study that first drew the media’s attention to the issue in 2011.
Each of these have suggested that injectable DMPA may increase a woman’s risk of HIV infection, but several previous studies have had quite different findings.
There are also real doubts as to whether the results are skewed by factors which the researchers haven’t been able to fully take into account, particularly differences in the sexual behaviour of contraceptive users and non-users. While studies have asked about condom use, the questions do not capture much detail and some women may give the answer that they think the researchers want to hear.
Moreover, in the studies that have found that DMPA increases the risk of acquiring HIV, the size of that effect has varied from something quite modest to a doubling of risk.
It is therefore clear that no single study should be treated as clearly answering the question, but that we need to look at systematic reviews and meta-analyses. These are analyses of all the previous studies that meet predefined requirements.
As well as Polis’ systematic review, Charles Morrison at FHI 360 is conducting a meta-analysis that is due to be made public later this year. It will pool the data from 18 studies, including around 37,000 women, over 1800 of whom became HIV positive. Crucially, it will look at individual patient data, rather than just each study’s published results – this should improve the quality of the data, analyses and results.
Source:1
