Urolithiasis in second-generation immigrant children younger than 18 years of age in Sweden

Aim: To compare incidence of urolithiasis in second-generation immigrant children aged 0-17 years to children of Swedish-born parents. Methods: A nationwide study of individuals residing in Sweden. Urolithiasis was defined as having at least one registered diagnosis of urolithiasis in the Swedish National Patient Register between January 1, 1998 and December 31, 2015. Cox regression analysis was used to estimate the relative risk (hazard ratios (HR) with 95% confidence intervals (CI)) of incident urolithiasis compared to individuals with Swedish-born parents. The models were stratified by sex and adjusted for age, co-morbidities and sociodemographic status of parents. Results: Totally, 1653 incident cases of urolithiasis were registered, 658 boys and 995 girls, with a mean annual incidence per 100 000 person-years for children with Swedish-born parents of 4.0 (95% CI 3.7-4.3) in boys and 6.7 (95% CI 6.2-7.2) in girls, and for children with foreign-born parents of 5.3 (95% CI 5.1-5.4) in boys and 7.2 (95% CI 6.9-7.4) in girls. The fully adjusted HRs of urolithiasis in second-generation immigrants were non-significant, in boys (1.20, 95% CI 0.99-1.46) and girls (0.95, 95% CI 0.80-1.12). Conclusion: The risk of urolithiasis in second-generation immigrants was not significantly different from that of children with Swedish-born parents.