HIV this week

Male circumcision reduces female-to-male HIV-1 transmission risk by approximately 60%. Data
assessing the effect of circumcision on male-to-female HIV-1 transmission are conflicting, with one observational study among HIV-1-serodiscordant couples showing reduced transmission but a randomized trial suggesting no short-term benefit of circumcision.

Data were collected as part of a prospective study among African HIV-1-serodiscordant couples were analyzed for the relationship between circumcision status of HIV-1-seropositive men and risk of HIV-1 acquisition among their female partners. Circumcision status was determined by physical examination. Cox proportional hazards analysis was used.

A total of 1096 HIV-1-serodiscordant couples in which the male partner was HIV-1-infected were followed for a median of 18 months; 374 (34%) male partners were circumcised. Sixty-four female partners seroconverted to HIV-1 (incidence 3.8 per 100 person-years). Circumcision of the male partner was associated with a nonstatistically significant approximately 40% lower risk of HIV-1 acquisition by the female partner (hazard ratio 0.62, 95% confidence interval 0.35-1.10, P = 0.10). The magnitude of this effect was similar when restricted to the subset of HIV-1 transmission events confirmed by viral sequencing to have occurred within the partnership (n = 50, hazard ratio 0.57, P = 0.11), after adjustment for male partner plasma HIV-1 concentrations (hazard ratio 0.60, P = 0.13), and when excluding follow-up time for male partners who initiated antiretroviral therapy (hazard ratio 0.53, P = 0.07).

 Among HIV-1-serodiscordant couples in which the HIV-1-seropositive partner was male, the authors observed no increased risk and potentially decreased risk from circumcision on male-to-female transmission of HIV-1.

HIV This Week Editors’ note:

The trend seen here among 1096 couples toward a protective effect of male circumcision for HIV-negative women in discordant partnerships is intriguing. Sexual behaviours of couples with circumcised men were similar to those in which the man was not circumcised, only genetically-linked transmissions (i.e. transmissions within the couple) were considered (incidence 3.0 per 100 person years), and follow-up time after initiation of antiretroviral treatment (when viral loads presumably fell) was excluded. The result was a borderline statistically significant 47 per cent reduced risk of HIV-1 acquisition in women. Possible mechanisms that might explain lower risk for women are reduced risk of sexually transmitted infections in circumcised men or reduced likelihood of direct HIV transmission that would have otherwise occurred as a result of microtrauma or inflammation of the foreskin.