Cultural background, non-therapeutic circumcision and the risk of meatal stenosis and other urethral stricture disease: Two nationwide register-based cohort studies in Denmark 1977-2013

Background: Meatal stenosis is markedly more common in circumcised than genitally intact males, affecting 5–20 per cent of circumcised boys. However, no population-based study has estimated the relative risk of meatal stenosis and other urethral stricture diseases (USDs) or the population attributable fraction (AF _p) associated with non-therapeutic circumcision. Methods: In two nationwide cohort studies (comprising 4.0 million males of all ages and 810 719 non-Muslim males aged 0–36 years, respectively), we compared hospital contact rates for USD during 1977–2013 between circumcised and intact Danish males. Hazard ratios (HRs) were obtained using Cox proportional hazards regression, and the AF _p estimated the proportion of USD cases in <10 year-old boys that is due to non-therapeutic circumcision. Results: Muslim males had higher rates of meatal stenosis than ethnic Danish males, particularly in <10 year-old boys (HR 3.44, 95 per cent confidence interval 2.42–4.88). HRs linking circumcision to meatal stenosis (10.3, 4.53–23.4) or other USDs (5.14, 3.48–7.60) were high, and attempts to reduce potential misclassification and confounding further strengthened the association, particularly in <10 year-old boys (meatal stenosis: 26.3, 9.37–73.9; other USDs: 14.0, 6.86–28.6). Conservative calculations revealed that at least 18, 41, 78, and 81 per cent of USD cases in <10 year-old boys from countries with circumcision prevalences as in Denmark, the United Kingdom, the United States and Israel, respectively, may be attributable to non-therapeutic circumcision. Conclusion: Our study provides population-based epidemiological evidence that circumcision removes the natural protection against meatal stenosis and, possibly, other USDs as well.