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 (AFp ) 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 AFp 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.