Does hormonal contraception increase the risk for a woman to acquire HIV from an infected partner?
This topic, with implications for public health in countries where HIV risk is high, has been contentious. Some previous studies had found the answer to be yes, for methods involving injectable progesterone such as Depo-Provera. This led the World Health Organization in 2012 to advise women using progesterone-only injections to use condoms to prevent HIV infection.
At the recent AIDS 2014 meeting in Australia, Emory epidemiologist Kristin Wall presented data from public health programs in Zambia. This is another study emerging from the Zambia-Emory HIV Research Project directed by Susan Allen.
Wall’s presentation is available here.
Studying 1393 heterosexual couples with a HIV-positive male partner over 17 years, Wall and her colleagues found no significant difference in incidence rate per 100 couple years between hormonal and non-hormonal forms of contraception.
How to account for these discrepancies? Several investigators in the field, including those at Emory, think that the appearance of a connection between hormonal contraception and HIV risk is confounded by unreported unprotected sex.
Wall reports her team measured both self-reported and biological measures of unprotected sex to assess potential effects on the statistics. They also took account of women switching their method of contraception, and HIV infections unlinked to the partnerâ€™s viral genotype. Some studies that have examined this issue examine all women in a high risk area rather than just those within HIV-discordant couples, whose risk is more defined, Wall notes.
â€œWe do view our results as being from one of the most robust and thorough analyses published to date,â€ she says.
Wall says she and her team are preparing a similar analysis of discordant couples where the female is HIV-positive, with results to be reported this fall.
A large clinical trial that will examine contraception/HIV risk connection is also being organized by FHI 360, WHO, University of Washington and several African research institutes.
Note: the proposed hypothetical mechanism for male to female transmission involves hormone-induced changes in the genital mucosa or possibly other STDs.