Efficacy and tolerability of mirabegron compared with solifenacin for children with idiopathic overactive bladder: A preliminary study

Purpose: To compare the efficacy and tolerability of mirabegron and solifenacin in pediatric patients with idiopathic overactive bladder (OAB) and to identify factors affecting OAB symptom improvement after treatment. Materials and Methods: We retrospectively reviewed 103 patients (5-15 years old) who visited our hospital with OAB symptoms between July 2017 and March 2019. All participants had received solifenacin or mirabegron. Those who had secondary OAB or who did not complete the frequency-volume chart either before or after treatment were excluded. The age-adjusted bladder capacity ratio was used to evaluate bladder capacity. Efficacy was assessed on the basis of patient reports and changes in the frequency-volume chart, and >= 90% reduction was regarded as "responding to medication." Tolerability was assessed by obtaining reports from patients about the adverse effects of the drug. Results: After the exclusion of 58 patients, 45 patients (29 in solifenacin-group and 16 in mirabegron-group) were included in the primary analysis. The age-adjusted bladder capacity ratio increased from 0.71 to 0.96 (p<0.001) and from 0.57 to 0.97 (p=0.002) after solifenacin and mirabegron use, respectively. Decreased bladder capacity before medication was associated with responding to medication (odds ratio, 7.41; p=0.044). There was no significant difference in efficacy between the two drugs. Drug-induced adverse effects were reported in only 3 (10.3%) of the solifenacin-treated patients. Conclusions: Mirabegron showed comparable efficacy to solifenacin in pediatric patients with idiopathic OAB. Additionally, only few adverse effects were reported, suggesting that mirabegron can be a safe alternative for the treatment of idiopathic pediatric OAB.