Studies Indicate that Circumcision Provides Minimal Protection against HIV Infection in Men who have Sex with Men

By Liz Highleyman

In recent years, studies have shown that adult male circumcision can help lower the risk of men becoming infected with HIV and other sexually transmitted infections (STIs), with a 50%-60% reduction in HIV incidence in 2 randomized studies of young heterosexual men in Kenya and Uganda.

It remains unclear, however, whether this benefit also extends to men who have sex with men (MSM), or to men in industrialized countries with a low overall HIV prevalence. At the 2007 National HIV Prevention Conference, Gregorio Millett from the Centers for Disease Control and Prevention (CDC) and colleagues present cross-sectional data showing no evidence that being circumcised was protective against HIV infection among black or Latino MSM in the U.S. But an analysis presented last month at the Australasian Sexual Health Conference suggested that circumcision might play a role in preventing HIV infection in some gay and bisexual men.

Now, in the October 8, 2008 Journal American Medical Association, Millett and colleagues present the results of a meta-analysis of previous studies performed to quantitatively summarize the strength of the association between circumcision and HIV infection and other STIs across observational studies of MSM.

The authors conducted a comprehensive search of databases including MEDLINE, EMBASE, ERIC, Sociofile, PsycINFO, Web of Science, and Google Scholar, and corresponded directly with researchers, to find relevant published articles, conference proceedings, and unpublished reports through February 2008.

Of 18 studies conducted between 1989 and 2007 that quantitatively examined the association between male circumcision and HIV or STIs among MSM, 15 (83%) met the defined selection criteria. The meta-analysis included a total of 53,567 study participants from the U.S., Canada, Australia, the UK, the Netherlands, Peru, India, and Taiwan, of whom 52% were circumcised.

Results

• The odds of being HIV positive were non-significantly lower among MSM who were circumcised compared with uncircumcised men (odds ratio 0.86 or 14% lower risk).

• Among MSM who primarily engaged in insertive anal sex, the association between male circumcision and HIV was protective, but again not statistically significant (odds ratio 0.71, or 29% lower risk).

• Male circumcision had a significant protective effect against HIV infection in studies conducted before the introduction of HAART in 1996, but not thereafter (odds ratio 0.47, or 53% lower risk).

• Circumcision had a stronger protective effect against HIV when circumcision prevalence in a population was 50% or lower (e.g., a 9% reduction in odds in the U.S. vs 15% in other developed countries vs 51% in developing countries).

• The association between circumcision and other STIs was not statistically significant (odds ratio 1.02, or 2% higher risk).

• Higher study quality was associated with a reduced odds of HIV infection among circumcised MSM (P = 0.01).

"Taken together, these findings indicate insufficient evidence among available observational studies conducted with MSM of an association between circumcision and HIV infection or other STIs," the study authors concluded.

However, they added, "the comparable protective effect of male circumcision in MSM studies conducted before the era of highly active antiretroviral therapy, as in the recent male circumcision trials of heterosexual African men, supports further investigation of male circumcision for HIV prevention among MSM."

In their discussion, the investigators suggested that with the introduction of HAART, effective therapy may have reduced the risk of HIV transmission to such an extent that circumcision does not provide further benefit. In addition, the availability of treatment may have led to shifts in attitudes and sexual risk behavior, including condom use.

"Our data revealed that male circumcision conferred a significant protective effect from HIV infection among MSM in studies conducted before HAART but not after, possibly due to documented increases in sexual risk behavior during the era since the availability of HAART," they wrote.

In an accompanying editorial, Sten Vermund and Han-Zhu Qian of Vanderbilt University School of Medicine noted that a previous meta-analysis of epidemiological studies published prior to 2000 suggested an association between circumcision and HIV infection among heterosexual African men, but confounding factors -- for example, the Islamic practice of circumcision in the context of lower sexual risk and norms against alcohol use -- could not be ruled out.

While the procedure may be protective for some MSM, they concluded that "circumcision would likely be insufficiently efficient to be universally effective in reducing HIV and will have to be combined with other prevention modalities to have a substantial and sustained prevention effect."

10/14/08

References

GA Millett, SA Flores, G Marks, and others. Circumcision status and risk of HIV and sexually transmitted infections among men who have sex with men a meta-analysis. Journal American Medical Association 300(14): 1674-1684. October 8, 2008. (Abstract).

SH Vermund and H-Z Qian. Circumcision and HIV prevention among men who have sex with men: no final word [Editorial]. Journal American Medical Association 300(14): 1698-1700. October 8, 2008.