IAS: Circumcision prevents three out of four female-to-male HIV infections.

The first ever randomised controlled trial (RCT) of male circumcision as an HIV prevention measure has produced such strong evidence of a protective effect that the trial has been halted early and all participants have been offered circumcision the Third International IAS Conference on HIV Pathogenesis and Treatment in Rio de Janeiro heard on July 26th 2005. There were only 35% as many infections in the circumcision arm as opposed to the control arm implying that circumcision can prevent at least six out of ten female-to-male HIV transmissions. However when the results were analysed according to true circumcision status rather than by intervention group the protective effect went up to 75%. This is because there were crossovers between the intervention and control arms in that some men randomised to be circumcised were not and some in the control arm were. (excerpt)