Research shows protective effect of male circumcision

Drops acquisition risk for at least 3.5 years

Just-presented research at the XVII International AIDS Conference in Mexico City indicates that adult male circumcision continues to reduce the risk of acquiring HIV through heterosexual intercourse for at least 3.5 years.1

This finding emerged from an analysis of long-term follow-up data on Kenyan men who have participated in a large clinical trial assessing the protective value of adult male circumcision against HIV infection.2 The new finding gives further weight to the 2007 World Health Organization recommendation that male circumcision be recognized as an additional important intervention to reduce the risk of heterosexually acquired HIV infection in men.3

Three trials examining adult male circumcision — the one in Kisumu, Kenya, another in Rakai, Uganda, and an earlier one in Orange Farm, South Africa — were halted when interim review of data showed medically performed circumcision significantly lowers a man's risk of acquiring HIV through heterosexual intercourse.4,5

One of the concerns that has been expressed about the evidence for male circumcision's protective effect against HIV acquisition has been that all three randomized controlled trials of circumcision were stopped before their planned completion, and the studies extended only 18-24 months, observes Robert Bailey, PhD, MPH, professor of epidemiology at the School of Public Health at University of Illinois at Chicago and lead author of the recently presented Kenya study. Skeptics have said that the protective effect of circumcision would be eroded after periods of longer than 24 months, he notes.

The paper presented at the 2008 AIDS conference reported a continuation of the Kenyan study, following circumcised and uncircumcised men for 42 months, Bailey points out. The results show that the 60% protective effect of circumcision against HIV acquisition in Kenyan heterosexual men that researchers found after 24 months of follow-up is sustained for at least 42 months, he says. The results show it possibly is strengthened to 65%, Bailey adds.

"These results lend further support to the addition of male circumcision to our currently limited armamentarium of HIV prevention interventions and reinforce the need to introduce safe, affordable, voluntary male circumcision in high HIV-prevalent populations as rapidly as possible," he says.

Review the results

As of May 2008, 1,545 of 1,739 men (89%) had consented to extended follow-up, with 767 in the circumcision group and 778 in the control group. A total of 1,491 remain on study. Of the 1,393 in the control group, 525 (38%) became circumcised. Age and number of sexual partners at baseline were the same in controls who did and did not circumcise. Median follow-up was 30 months.

There were 27 HIV seroconversions in circumcised men and 62 in uncircumcised men, researchers report. The 42-month cumulative seroincidence was 2.6% [95% confidence interval (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- to 30-, 30- to 36-, and 36- to 42-month follow-up intervals were 0.3%, 0.2%, and 0.7%, respectively, in the circumcision group vs. 1%, 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. Those results support expeditious provision of safe, affordable circumcision services as part of comprehensive HIV prevention strategies, researchers conclude.1

How many men in the United States are circumcised? About 80%, according to national probability samples of adults surveyed during 1999–2004 through the National Health and Nutrition Examination Surveys. This figure includes 88% of non-Hispanic white men, 73% of non-Hispanic black men, 42% of Mexican-American men, and 50% of men of other races/ethnicities.6

Data on circumcision and risk for HIV infection in the United States are limited, according a review of research by the Centers for Disease Control and Prevention (CDC).7 In one cross- sectional survey of men who have sex with men (MSM), lack of circumcision was associated with a twofold increase in the odds of prevalent HIV infection.8 Results from a prospective study of MSM indicate that lack of circumcision was associated with a twofold increase in risk for HIV seroconversion.9 In both studies, the results were statistically significant, and the data have been controlled statistically for other possible risk factors, the CDC review states.

Other studies have not followed suit. In a prospective cohort study of MSM, there was no association between circumcision status and incident HIV infection, even among men who reported no unprotected anal receptive intercourse.10

AAP reviews policy

According to the National Hospital Discharge Survey, 65% of U.S. newborns were circumcised in 1999, with the overall proportion of newborns circumcised stable from 1979 through 1999.11

In 1999, the American Academy of Pediatrics (AAP) revised its neutral stance on circumcision to a position that the data then available were insufficient to recommend routine neonatal male circumcision. In the 1999 position paper, the organization stated, "It is legitimate for the parents to take into account cultural, religious, and ethnic traditions, in addition to medical factors, when making this choice."12 The organization reaffirmed its position in 2005.7

The original 1999 AAP policy on circumcision still is current, says Debbie Linchesky, an AAP spokeswoman. A new task force is updating the policy; however, it has not been released as of press time, she says. No projected release date has been issued, she states. (Editor's note: CTU will cover the updated policy as soon as it is released.)


  1. Bailey RC, Moses S, Parker CB, et al. The protective effect of male circumcision is sustained for at least 42 months: Results from the Kisumu, Kenya Trial. Presented at the XVII International AIDS Conference. Mexico City; August 2008.
  2. Bailey C, Moses S, Parker CB, et al. Male circumcision for HIV prevention in young men in Kisumu, Kenya: A randomized controlled trial. Lancet 2007; 369:643-656.
  3. World Health Organization/UNAIDS. New Data on Male Circumcision and HIV Prevention: Policy and Programme Implications. Conclusions and Recommendations. Montreux, Switzerland; March 2007. Accessed at
  4. Gray H, Kigozi G, Serwadda D, et al. Male circumcision for HIV prevention in young men in Rakai, Uganda: A randomized trial. Lancet 2007; 369:657-666.
  5. Auvert B, Taljaard D, Lagarde E, et al. Randomized, controlled intervention trial of male circumcision for reduction of HIV infection risk: The ANRS 1265 Trial. PLoS Med 2005; 2(11): e298.
  6. Xu F, Markowitz LE, Sternberg MR, et al. Prevalence of circumcision and herpes simplex virus Type 2 infection in men in the United States: the National Health and Nutrition Examination Survey (NHANES), 1999–2004. Sex Transm Dis 2007; 34:479-484.
  7. Centers for Disease Control and Prevention. CDC HIV/ AIDS Science Facts: Male Circumcision and Risk for HIV Transmission and Other Health Conditions: Implications for the United States. Fact sheet; accessed at
  8. Kreiss JK, Hopkins SG. The association between circumcision status and human immunodeficiency virus infection among homosexual men. J Infect Dis 1993; 168:1,404-1,408.
  9. Buchbinder SP, Vittinghoff E, Heagerty PJ, et al. Sexual risk, nitrite inhalant use, and lack of circumcision associated with HIV seroconversion in men who have sex with men in the United States. J Acquir Immune Defic Syndr 2005; 39:82-89.
  10. Templeton DJ, Jin F, Prestage GP, et al. Circumcision status and risk of HIV seroconversion in the HIM cohort of homosexual men in Sydney. Presented at Fourth IAS Conference on HIV Pathogenesis, Treatment, and Prevention; July 2007.
  11. Centers for Disease Control and Prevention. Trends in Circumcisions among Newborns. Fact sheet. Accessed at
  12. American Academy of Pediatrics, Task Force on Circumcision. Circumcision policy statement. Pediatrics 1999; 103:686-693.