Hormonal contraceptives increase risk of HIV infection

Hormonal contraceptives increase the risk of a woman becoming infected with HIV, according to research conducted amongst Kenyan sex workers and presented to the Second International AIDS Society Conference on HIV Pathogenesis and Treatment in Paris on July 14^th.

Investigators were presenting the results of a ten year prospective study from a cohort of commercial sex workers in Mombasa, Kenya. Previously published four year data from the same cohort demonstrated that the injectable contraceptive medroxyprogesterone was associated with a two-fold increased risk of HIV infection.

Hormonal contraceptives have been shown to cause systemic changes and changes in the genital tract which have the potential to interact with HIV and increase a woman's change of being infected with the virus.

The study involved a cohort of 1272 HIV-negative commercial sex workers who attended a sexual health clinic every month for a sexual health screen and HIV test. Details of sexual practices and hormonal contraceptive use were also obtained.

A total of 248 women seroconverted for HIV. This represented an HIV incidence rate of 8.5 per 100 patient years of follow-up.

Vaginal unprotected sex was the only HIV risk factor reported by almost all the women, with less than 1% reporting anal sex.

Multivariate analysis, which controlled for other factors that increase the risk of HIV infection, including types of sexual behaviour, condom use, and sexually transmitted infections, found that women using hormonal contraceptives were at a significantly increased risk of being infected with HIV. Further, the investigators found that this increased risk existed irrespective of whether women were using injectable or oral contraceptives (HR 1.5, 95% CI, 1.0 – 2.1, p=0.03).

The investigators concluded that hormonal contraceptives significantly increased the risk of becoming HIV-positive, and that condom use should be vigorously promoted to women at risk of HIV who use both injected and oral contraceptives.