Impact of excluded studies on medical male circumcision and HIV risk compensation

Yanxiao Gao and colleagues (July, 2021)¹ present a systematic review and meta-analysis on the important topic of the association between voluntary medical male circumcision and HIV risk compensation among heterosexual men. Their findings indicate that there were no significant associations between medical male circumcision and multiple sex partners or condomless sex, suggesting that medical male circumcision does not increase higher risk sexual behaviours in heterosexual men.

Notably, a study conducted in Zambia² (not included in Gao and colleagues’ systematic review and meta-analysis) considered condom use and the number of sexual partners and reported a tendency towards risk compensation in circumcised men and no reduction in HIV prevalence. For example, circumcised men were reported to have had significantly more extramarital partners (11·1% vs 8·7%; p<0·05) in the 12 months before the Demographic and Health Survey.² We believe such differences, even if small, point towards risk compensation.

This study was published before November, 2020, based on nationally representative Demographic and Health Survey data, but was not included in the meta-analysis by Gao and colleagues even though “HIV”, “circumcised”, and “riskier sexual behaviour” are mentioned in the abstract of the study. AMSTAR-2 (a measurement tool to assess systematic reviews), which is an important appraisal tool for systematic reviews that includes randomised or non-randomised studies of health-care interventions, recommends that authors provide a list of excluded studies and justify exclusions.³ Gao and colleagues did not provide such a list; thus, it is not possible to ascertain the impact of exclusions on their study. Given the importance of the topic, providing the list and reasons for the excluded studies would be pertinent.

We declare no competing interests.