Role of body mass index in school-aged children with lower urinary tract dysfunction: Does weight classification predict treatment outcome?

INTRODUCTION: Lower urinary tract (LUT) dysfunction comprises a large percentage of pediatric urology referrals. Childhood obesity is a major health concern, and has been associated with voiding symptoms. We assessed the impact of body mass index (BMI) on treatment outcomes of children presenting with LUT or bladder-bowel dysfunction (BBD).

STUDY DESIGN: Children aged 5-17 years diagnosed with non-neurogenic LUT dysfunction and no prior urologic diagnoses were identified. Patient demographics including BMI, lower urinary tract symptoms, constipation, medical and psychologic comorbidities, imaging, and treatment outcomes were evaluated. BMI was normalized by age and gender according to percentiles: underweight < 5th, healthy 5th to <85th, overweight 85th to <95th, and obese > 95th percentile. Uni- and multivariate analyses were performed to identify predictors of treatment response.

RESULTS: During an 18-month period, 100 children (54 girls, 46 boys) met the inclusion criteria. The mean age at diagnosis was 7.7 ± 2.4 years, and mean length of follow-up 15.3 ± 13.1 months. Sixty-nine patients were a normal weight, 22 were overweight, and nine were obese. Fifteen percent of the children had complete treatment response, 63% partial response, and 22% non-response. On univariate analysis, children with elevated BMI (p = 0.04) or history of urinary tract infection (p = 0.01) were statistically more likely to not respond to treatment. Controlling for all other variables, children with BMI > 85th percentile had 3.1 times (95% CI 1.11-8.64; p = 0.03) increased odds of treatment failure (Table).

DISCUSSION: BBD management includes implementation of a bowel program and timed voiding regimen, with additional treatment modalities tailored on the basis of the prevailing symptoms. We observed that school-aged children with a BMI ≥ 85th percentile were over three times more likely to experience treatment failure when controlling for all other patient characteristics including constipation and a history of urinary tract infection. Limitations of the study include the relatively small sample size, lack of uroflow with electromyography to confirm the presence or the absence of detrusor sphincter dyssynergia, and inconsistent anticholinergic dosing.

CONCLUSIONS: Nearly one-third of school-aged children presenting to our institution with LUT or BBD were overweight or obese when normalized for age and gender. Children with LUT dysfunction and elevated BMI are significantly less likely to experience treatment response.