A systematic review including 12 studies (1 RCT, n=70; 4 cohort studies, n=400 700 and 7 case-control studies, n=2 138) with a total of 402 908 subjects was abstracted in DARE. The included studies mostly recruited babies or children (3 months to 10 years of age); one study recruited only adult males being treated at a genitourinary clinic. The RCT showed no statistically significant reduction in the incidence of urinary tract infection (UTI) with circumcision (OR 0.13, 95% CI 0.01 to 2.63). The cohort studies showed a statistically significant reduction in the incidence of UTI with circumcision (OR 0.13, 95% CI 0.07 to 0.24). There was significant heterogeneity between these studies, which was eliminated on the removal of one study from the analysis. The case-control studies showed a statistically significant reduction in the incidence of UTI with circumcision (OR 0.13, 95% CI 0.07 to 0.23). Overall, across study designs, there was a statistically significant reduction in the incidence of UTI with circumcision (OR 0.13, 95% CI 0.08 to 0.20). There was significant heterogeneity between these studies, again eliminated by the removal of the cohort study.
Given a risk in normal boys of about 1%, the number-needed-to-treat to prevent one UTI is 111. In boys with recurrent UTI or high grade vesicoureteric reflux, the risk of UTI recurrence is 10% and 30% and the numbers-needed-to-treat are 11 and 4, respectively. Haemorrhage and infection are the commonest complications of circumcision (risk of complications was not assessed in this review) occurring at rate of about 2%. The authors conclude that assuming equal utility of benefits and harms, net clinical benefit is likely only in boys at high risk of UTI.
Comment: The quality of evidence is upgraded by large magnitude of effect.