Purpose: Randomized trials from Africa demonstrate that circumcision reduces the risk of acquiring human immunodeficiency virus (HIV) among males. However, few studies have examined this association in Western populations. We sought to evaluate the association between circumcision and the risk of acquiring HIV among males from Ontario, Canada.
Materials and methods: We conducted a population-based matched cohort study of residents in Ontario, Canada. We identified males born in Ontario who underwent circumcision at any age between 1991 and 2017. The comparison group consisted of age-matched males who did not undergo circumcision. The primary outcome was incident HIV. We used cause-specific hazard models to evaluate the hazard of incident HIV. We performed several sensitivity analyses to evaluate the robustness of our results: matching on institution of birth, varying the minimum followup period, and simulating various false-negative and false-positive thresholds.
Results: We studied 569,950 males, including 203,588 who underwent circumcision and 366,362 who did not. The vast majority of circumcisions (83%) were performed prior to age 1 year. In the primary analysis, we found no significant difference in the risk of HIV between groups (adjusted hazard ratio 0.98, 95% confidence interval 0.72 to 1.35). In none of the sensitivity analyses did we find an association between circumcision and risk of HIV.
Conclusions: We found that circumcision was not independently associated with the risk of acquiring HIV among males from Ontario, Canada. Our results are consistent with clinical guidelines that emphasize safe-sex practices and counseling over circumcision as an intervention to reduce the risk of HIV.
Keywords: HIV; circumcision; cohort study; male; primary prevention.