Three large studies in South Africa, Zimbabwe and Kenya have found no evidence that men who have been circumcised have more sexual risk behaviours than uncircumcised men. Two of the studies were reported last week at the Conference on Retroviruses and Opportunistic Infections (CROI 2017) in Seattle; the third was published in the February issue of the Journal of Acquired Immune Deficiency Syndromes.

Voluntary male medical circumcision reduces men's risk of acquiring HIV by 60%. However, ‘risk compensation’ or ‘behavioural disinhibition’ after circumcision could mitigate or negate the protective effect of circumcision in reducing HIV infection if people changed their sexual behaviour as a result of perceiving themselves to be less at risk of infection.

Katrina Ortblad and colleagues examined longitudinal demographic surveillance data from the Africa Health Research Institute’s cohort in KwaZulu-Natal, South Africa. Almost 15,000 men contributed data from 2003 to 2014, including 13% who had been circumcised and 6% who were circumcised whilst in the cohort.

Glossary voluntary male medical circumcision (VMMC) The surgical removal of the foreskin of the penis (the retractable fold of tissue that covers the head of the penis) to reduce the risk of HIV infection in men. circumcision The surgical removal of the foreskin of the penis (the retractable fold of tissue that covers the head of the penis) to reduce the risk of HIV infection in men. risky behaviour In HIV, refers to any behaviour or action that increases an individual’s probability of acquiring or transmitting HIV, such as having unprotected sex, having multiple partners or sharing drug injection equipment. longitudinal study A study in which information is collected on people over several weeks, months or years. People may be followed forward in time (a prospective study), or information may be collected on past events (a retrospective study). statistical significance Statistical tests are used to judge whether the results of a study could be due to chance and would not be confirmed if the study was repeated. If result is probably not due to chance, the results are ‘statistically significant’.

‘Risk compensation’ was assessed by considering four aspects of sexual behaviour: not using a condom the last time the man had sex, never using condoms, the number of sexual partners, and the number of concurrent sexual relationships. As well as simply comparing circumcised and uncircumcised men, the researchers also compared behaviour before and after an individual’s circumcision.

None of these comparisons showed any statistically significant differences – the researchers found no evidence for risk compensation following circumcision. If anything, men who were circumcised had slightly decreased risk-taking behaviour, although the differences weren’t statistically significant.

Daniel Montano and colleagues followed a cohort of 2379 men who received an HIV-negative test result and were referred to Zimbabwe’s voluntary male medical circumcision programme. Around half chose to accept the offer of circumcision, while half did not. The researchers did not provide any risk reduction counselling in addition to that routinely provided by the national programme.

Sexual behaviour was measured for up to two years following circumcision. The researchers found no evidence that circumcised men had greater increases in risk behaviour over time than uncircumcised men. There were some increases in risk behaviour in both groups (for example, not using condoms, partner numbers and concurrent relationships), which the researchers suggest might be linked to the wider availability of HIV treatment in Zimbabwe at the time.

Matthew Westercamp and colleagues conducted three cross-sectional surveys of randomly sampled households in Kisumu, Kenya – the location for one of the three pivotal randomised controlled trials of male circumcision for HIV prevention. During a five year period, 7507 people took part in the three surveys.

The prevalence of male circumcision increased steadily from 32% in 2009 to 49% in 2011 to 60% in 2013. This was associated with a fall in sexually transmitted infections in the community, especially in circumcised men. But there were no differences observed between circumcised and uncircumcised men in sexual behaviour (including condom use and number of sexual partners) or in knowledge about HIV or perception of HIV risk.

All three groups of researchers recommend that voluntary male medical circumcision should continue to be scaled up.