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The protective effect of adult male circumcision against
HIV acquisition is sustained for at least 54 months: results from the Kisumu,
Kenya trial
R.C. Bailey1, S. Moses2, C.B. Parker3, K. Agot4, I. MacLean2, J.N. Krieger5, C.F.M. Williams6, J.O. Ndinya-Achola7
1University of Illinois at Chicago, School of Public Health, Chicago, United States, 2University of Manitoba, Winnipeg, Canada, 3RTI InternationalI, Research Triangle, United States, 4Impact Research and Development Organization, Kisumu, Kenya, 5University of Washington, Seattle, United States, 6National Institute for Allergy and Infectious Diseases, DAIDS, Rockville, United States, 7University of Nairobi, Medical Microbiology, Nairobi, Kenya
Background: In
a randomized controlled trial in Kisumu, Kenya, involving 2,874 men aged 18-24
years at enrollment, we previously reported a 60% protective effect of male
circumcision against HIV acquisition at 24 months after enrollment, and 64% at
42 months, based on modified as-treated analyses. We now report sustained
protection against HIV infection extending to at least 54 months of follow-up.
Methods: The
trial was unblinded in December 2006, when all participants were offered
circumcision, regardless of initial treatment assignment (immediate versus
delayed circumcision). HIV/STI testing
and behavioural interviews were conducted semiannually in extended
follow-up. Relative risk was estimated using
a modified as-treated analysis.
Results: As of March 2010, 1552 of 1740 men (89%)
consented to extended follow-up (n=767 circumcision group; n=785 controls); 1469
remain on study. 619 of 1393 controls (44%)
were circumcised. Age and number of
sexual partners at baseline were the same in controls who did and did not elect
to be circumcised. The median follow-up was 36 months. There were 36 HIV seroconversions in men randomized
to circumcision and 82 in controls over 54 months. The 54 month cumulative
seroincidence was 4.1% (95% CI 2.9, 5.8) among men randomized to immediate
circumcision and 8.8% (7.0, 10.9) among controls (p< 0.0002). The relative
risk of HIV infection in circumcised men was 0.37 (0.25, 0.54), corresponding
to a 63% (46, 75) protective effect.
Conclusions: The protective effect of circumcision against
HIV acquisition among sexually active men seen after 24 and 42 months of
follow-up was sustained to at least 54 months. Concerns about the potential for
reduced protection offered by circumcision over time appear unfounded based on
follow up of 4.5 years. Our results support expeditious provision of safe, voluntary
male circumcision services as part of comprehensive HIV prevention strategies.
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