Circumcision is associated with a lower rate of HIV infection among men who have sex with men (MSM) in low- and middle-income nations, according to a new systematic review and meta-analysis.

Publishing their findings in The Lancet Global Health, researchers identified 62 observational studies conducted between 1989 and 2016 that provided statistics regarding HIV, sexually transmitted infection (STI) diagnoses or both according to whether MSM were circumcised.

A series of randomized controlled trials published during the mid-2000s found that voluntary medical male circumcision was associated with about a 60 percent reduced risk of female-to-male transmission of HIV. As a result of these findings, there has been a massive push to circumcise males in sub-Saharan Africa—an effort that multiple studies have found has been associated with lower HIV rates not just among men but among women as well.

The new paper’s authors looked at 45 studies that compared HIV rates among 105,009 MSM with the men’s circumcision status. Being circumcised was associated with a 23 percent lower rate of HIV. When breaking down the findings according to the wealth of MSM’s home nation, the study authors found that circumcision was linked to a 42 percent lower HIV rate among MSM in low- and middle-income countries and had no association with the diagnosis rate among MSM in high-income countries.

Speculating on why circumcision was associated with lower HIV rates only among MSM in poorer nations, the researchers posited that it may be more common for MSM to adhere to a single role in anal sex—more men are exclusively an insertive partner, or the top—in poorer nations compared with high-income countries. (Circumcision would provide no protection to an HIV-man engaging in receptive anal intercourse with an HIV-positive man with a transmissible viral load.) The poorer nations may also have a higher rate of MSM who also have sex with women. Additionally, the high prevalence of HIV in the lower-income nations and an overall lack of HIV prevention resources for MSM in such nations may be factors.

When the study authors restricted their analysis to studies that adjusted their findings to rule out various other factors that may contribute to HIV risk among MSM, they found that circumcision was tied to a 36 percent lower risk of infection.

The researchers also analyzed 27 studies regarding STI diagnoses that included 61,411 MSM and found no strong evidence that circumcision was associated with a reduced risk of STIs overall. However, circumcision was tied to a 16 percent lower risk of herpes simplex virus infection and a 29 percent lower risk of penile human papillomavirus.

To read the aidsmap article, click here.

To read the letter, click here.