Male circumcision doesn't affect women's HIV risk

Male circumcision has “little influence” on a woman’s HIV risk, according to a study conducted in Uganda and Zimbabwe published in the August 20^th edition of AIDS. However, the study did show that women with high levels of sexual risk were slightly less likely to contract HIV if their partners were circumcised, and the investigators suggest that this finding should be explored in further studies.

Three randomised controlled trials have now shown that circumcised men might have a significantly lower risk of HIV infection than uncircumcised men. It is uncertain, however, if male circumcision has a protective effect against HIV infection for women. The studies that have examined this question have so far yielded conflicting results.

It is biologically plausible that women with circumcised partners have a lower risk of HIV infection. Uncircumcised men could be more likely to transmit HIV because the foreskin contains cells capable of shedding HIV and the foreskin also provides an environment where microorganisms can grow. Studies have also shown that uncircumcised men are more likely to have genital ulcers, and the presence of ulcers can facilitate the transmission of HIV.

In the current study, the effect of male circumcision on women’s HIV risk was examined by analysing data from the Hormonal Contraception and the Risk of HIV Acquisition (HC-HIV) study.

Data from 4417 sexually active women aged between 18 – 35-years in Uganda and Zimbabwe were included in the investigators’ analyses. The study population comprised 2,231 Zimbabwean women (50% of the population) and 1,793 Ugandan women assessed as having a low HIV risk (41%).

In addition, a further 393 Ugandan women with a high HIV risks, including patients from sexually transmitted infection clinics, sex workers, and military wives, were included in the study.

At baseline women were asked to say if their partner was circumcised or not. Women were also asked to provide details of the circumcision status of any new sexual partners.

At enrollment structured interviews were also used to obtain details of the women’s reproductive, contraceptive, and sexual behaviours. Follow-up visits, including physical examinations and specimen collection, took place every twelve weeks. All the women were HIV-negative on enrollment.

Almost three-quarters of the women (3,249, 74%) at baseline reported that their partner was uncircumcised. A total of 989 (22%) said their partner was circumcised, and 166 (4%) reported that they did not know the circumcision status of their partner.

Circumcision was more common amongst the partners of Ugandan (36%) women then Zimbabwean (9%) women. But Zimbabwean women accounted for 98% of those who said that they did not know if their partner was circumcised.

Women with a circumcised partner had a riskier sexual background, having an earlier mean age of sexual debut (17 years versus 18 years, p < 0.001), a higher number of mean life-time sexual partners (five versus three, p < 0.001), and a higher mean number of nights when their partner was away from home in the last month (nine versus six, p < 0.001).

The median duration of follow-up was 23 months.

Consistent with the baseline findings, women partnered with circumcised partners had higher levels of sexual risk during follow-up, being more likely than women with uncircumcised partners to self-report a sexually transmitted infection (6% versus 4%, p < 0.001), have symptoms of a sexually transmitted infection (26% versus 20%, p < 0.001), and to have a risky sexual partner (a man with symptoms of a sexually transmitted infection, or who was HIV-positive; 23% versus 14%, p < 0.001). Women with circumcised partners also had a lower mean number of protected sex acts (8.6 versus 8.3 per month, p < 0.001).

A total of 210 women became infected during follow-up (34 women with circumcised partners, 167 women with uncircumcised partners, and nine women who did not know the circumcision status of their partners). This provided an unadjusted HIV incidence of 2.03 per 100 person years for women with circumcised partners, 2.96 per 100 person years for women with uncircumcised partners, and 3.51 per 100 person years from women who did not know if their partner was circumcised.

The investigators then performed a number of statistical analyses. In their first unadjusted model, they found that the risk of HIV infection was reduced for women with circumcised partners compared to women whose partners were uncircumcised (HR, 0.69; 95% CI, 0.48 – 0.99). This difference was of border-line statistical significance (p = 0.06).

But the protective effect of having a circumcised partner weakened when the investigators adjusted their model to include age, age at sexual debut, contraceptive use, husband’s employment status, level of education, and number of sexual partners in the previous three months (HR, 0.78; 95% CI, 0.53 – 1.14, p value not provided). Further adjustment, taking into account population subgroups, meant that the protective effect of circumcision disappeared entirely (HR, 1.03, 95% CI, 0.69 – 1.53).

In further analysis, the women’s HIV risk group was then taken into consideration. The investigators found that low-risk Ugandan and Zimbabwean women had a similar risk of HIV infection, regardless of their partner’s circumcision status. However, the high-risk Ugandan women derived a non-significant protective effect from having a circumcised partner (HR 0.16; 95% CI, 0.02 – 1.25).

“After adjustment, we did not observe a significant protective effect of male circumcision overall…for a small group referred through high-risk settings, we found a suggestion of a lower HIV risk for women with circumcised partners,” write the investigators, adding that the finding for this high-risk subgroup “is based on few HIV infections (19 total infections, and only two among women with circumcised partners), and, therefore the suggestion that male circumcision may be protective for these high-risk women must be interpreted very tentatively.” Nevertheless, they conclude that this finding “warrants further investigation.”