Circumcision protects against HIV over long term
Tuesday, 27 July 2010- Male circumcision appears to be protective against HIV for at least four and a half years, a researcher said during the International AIDS Conference (IAC) held in Vienna, Austria.
The finding from an observational follow-up to a major randomised trial initially conducted among more than 1,700 men, should put to rest fears that the effects of circumcision "would be eroded" over time, according to Dr. Robert Bailey of the University of Illinois at Chicago School of Public Health.
Three large randomised trials, all conducted in Africa among heterosexual men, showed that men who were circumcised were significantly less likely to catch HIV from infected female partners; one of the studies was done in Kenya and led by Bailey and colleagues.
However, one of the concerns "has been that all three circumcision trial were stopped early," with only 18 and 24 months of follow-up, Bailey told a late-breaker session at the IAC. To try to clarify the issue, he said researchers in Kisumu, Kenya have been following their study participants, including controls (who were offered immediate circumcision when the trial was halted) over 54 months since the end of the original trial.
In that original trial, Bailey said, the protective effect of adult male circumcision was shown to be about 60% -- with an incidence of HIV in the active arm of 1.8% compared with 4.0% among controls.
More than 1,500 HIV-negative participants agreed to take part in the follow-up to the trial, including 767 in the circumcision group and 785 in the original control group -- of whom 49% have since agreed to the procedure. The follow-up analysis showed no differences between controls who agreed to be circumcised and those who did not, nor were there differences between the former controls and men in the original circumcision group, Bailey said.
Analysis over 54 months showed:
•Among the circumcised men, there were a cumulative total of 34 cases of HIV, including during the original trial period.
•Among the men who were not circumcised, there were 77 cases of HIV.
However, Bailey noted that the number of men at risk in each arm was not the same. For instance, he said, at 54 months, there were 523 circumcised men and 273 uncircumcised men, with four and five seroconversions respectively in that month.
Overall, he said, the incidence of HIV among the circumcised men was 4.0%, compared with 10.6% among the others, yielding a relative risk for acquiring HIV of 0.36 (95% CI, 0.24 to 0.55).
On an annualized basis, he said, the rate of HIV infections among circumcised men was 0.91 per 100 person-years of follow-up, compared with 2.45 among the uncircumcised. The difference was significant at P=0.0007, he said.
Bailey cautioned that the original randomisation no longer holds; the study has become observational. On the other hand, he added, the study shows that the protective effect of circumcision is "clearly sustained, and possibly strengthened, over 4.5 years of study."
This is a "very important study showing that the effect lasts longer than the original trial," said Maria Prins of the Amsterdam Public Health Service, who was not part of the study but moderated the late-breaking session.
Source: R.C. Bailey et al. "The protective effect of adult male circumcision against HIV acquisition is sustained for at least 54 months: results from the Kisumu, Kenya trial," International AIDS Conference 2010, Vienna, Austria; abstract FRLBC101.
