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The protective effect of male circumcision is sustained for at least 42 months: results from the Kisumu, Kenya Trial
Presented by Robert C. Bailey, United States.
R.C. Bailey1, S. Moses2, C.B. Parker3, K. Agot4, I. Maclean5, J.N. Krieger6, C.F. Williams7, J.O. Ndinya-Achola8
1University of Illinois at Chicago, School of Public Health, Chicago, United States, 2University of Manitoba, Community Health Sciences and Medicine, Winnipeg, Canada, 3RTI International, Statistics and Epidemiology Division, RTP, North Carolina, United States, 4UNIM Clinic and University of Manitoba, Community Health Sciences and Medicine, Winnipeg, Canada, 5University of Manitoba, Department of Medical Microbiology, Winnipeg, Canada, 6University of Washington School of Medicine, Department of Urology, Seattle, Washington, United States, 7National Institute of Allergy and Infectious Disease, Division of AIDS, Bethesda, MD, United States, 8University of Nairobi, Department of Medical Microbiology, Nairobi, Kenya
Background: We previously reported, based on 24 months of follow-up, a 53-60% protective effect of male circumcision against HIV acquisition in a randomized controlled trial with 2874 men aged 18-24 years at enrollment in Kisumu, Kenya. We now report results extending to 42 months of follow-up.
Methods: The trial was stopped early in December 2006 and all participants were offered circumcision regardless of assignment (immediate versus delayed circumcision). HIV/STI testing and behavioural interviews were conducted semiannually in extended follow-up. HIV seroincidence was estimated according to original treatment group. Relative risk was estimated in an as-treated analysis.
Results: As of May 2008, 1545 of 1739 men (89%) consented to extended follow-up (n=767 circumcision group; n=778 controls); 1491 remain on study. 525 of 1393 controls (38%) became circumcised. Age and number of sexual partners at baseline were the same in controls who did and did not circumcise. The median follow-up was 30 months. There were 27 HIV seroconversions in circumcised men and 62 in uncircumcised men. The 42 month cumulative seroincidence was 2.6% (95% CI 1.4, 3.9) among men randomized to immediate circumcision and 7.4% (5.2, 9.5) among controls (p=0.0002); rates for 24-30, 30-36 & 36-42 month follow-up intervals were 0.3%, 0.2%, and 0.7%, respectively, in the circumcision group versus 1.0%, 1.3% and 1.6% for controls. The relative risk of HIV infection in circumcised men was 0.36 (0.23, 0.57), corresponding to a 64% (43, 77) protective effect.
Conclusions: The protective effect of circumcision against HIV acquisition among sexually active men seen over 24 months of follow-up is sustained, and possibly strengthened, to 42 months. Results support expeditious provision of safe, affordable circumcision services as part of comprehensive HIV prevention strategies.
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