Frequency of wetting is predictive of response to anticholinergic treatment in children with overactive bladder.

OBJECTIVES: To examine the variables relative to the response of oxybutynin treatment in children with daytime urinary incontinence.

METHODS: The records of patients seen for voiding problems between 1999 and 2003 were reviewed. Patients taking oxybutynin for 3 months or longer were included in the study. Patients with structural or neurologic bladder abnormalities and those taking oxybutynin at the initial visit were excluded. Age, sex, uroflowmetry findings, postvoid residual urine volume, duration and severity of symptoms before oxybutynin, urinary tract infection history, constipation, and the duration, dosage, and adverse effects of oxybutynin treatment were evaluated. Data were analyzed using Fisher's exact test for categorical variables, the two-sample t test or Wilcoxon rank-sum test for continuous and ordinal variables, and the linear mixed model analysis for uroflow data.

RESULTS: Eighty-one patients met the inclusion criteria. After an average follow-up of 1.2 years, 31 (38.3%) were dry, 25 (30.9%) had experienced significant improvement, 19 (23.5%) had experienced slight improvement, and 6 (7.4%) were unchanged. No significant differences were detected between those who became dry and those with little to no improvement with respect to age, sex, duration of symptoms, follow-up, uroflow pattern, postvoid residual urine volume, or bladder capacity. Those children presenting with decreased frequency of wetting episodes were significantly more likely to obtain daytime continence. The most common side effects were constipation (18.5%), dry mouth (17.3%), and flushing (13.6%).

CONCLUSIONS: Children with daytime incontinence presenting with the lowest frequency of wetting were most likely to achieve continence. The frequency of wetting should be considered a significant prognostic variable when assessing the results of therapeutic intervention trials.