Association Between Body Mass Index and Urolithiasis in Children

PurposeThe prevalence of obesity and urolithiasis in children has increased with time. We evaluated the relationship between body mass and urolithiasis in children.Materials and MethodsWe performed a matched case-control study in a network of 30 primary care pediatric practices. Cases included subjects with ICD-9 codes for urolithiasis and controls were matched on age, duration of observation before the index date and clinical practice. Age and sex specific body mass index z scores at the time of the stone episode were calculated. Continuous body mass index z scores and clinical weight categories were evaluated with covariates, including race, ethnicity, gender and payer status. The OR and 95% CI were calculated using multivariate conditional logistic regression.ResultsWe identified 110 cases and 396 matched controls, of whom 1.9% and 4.3% were overweight, and 3.7% and 4.5% were obese, respectively. On multivariate conditional logistic regression analysis the continuous body mass index z score (OR 0.84, 95% CI 0.63–1.12, p = 0.18), overweight status (OR 0.13, 95% CI 0.01–1.18) and obese status (OR 0.18, 95% CI 0.02–1.40) were not associated with urolithiasis. However, black race (OR 0.35, 95% CI 0.15–0.85) and Medicaid payer status (OR 0.47, 95% CI 0.24–0.93) were associated with a significant decrease in the odds of urolithiasis.ConclusionsHigh body mass was not associated with urolithiasis in our primary care pediatric practice network. However, black race and Medicaid payer status were associated with decreased odds of urolithiasis.