Long-term beneficial effects of mirabegron in pediatric patients with therapy-refractory neurogenic lower urinary tract dysfunction

Abstract

Neurogenic lower urinary tract dysfunction (NLUTD) in children can cause renal failure and urinary incontinence if not treated sufficiently. Antimuscarinics (AM) and intradetrusor botulinum toxin injections (BoNT-A) with clean intermittent catheterization (CIC) are widely used treatment options for children with NLUTD. However, a considerable number will become refractory to these treatment options. This study aimed to evaluate the efficacy and long-term outcomes of mirabegron in children with NLUTD as an add-on and as a stand-alone treatment. Patients under 18 years of age with NLUTD who were refractory to AM and/or BoNT-A and were treated with mirabegron 50mg were retrospectively studied. Mirabegron was either used as monotherapy or in addition to AM and/or BoNT-A. Video-urodynamic studies (VUDSs) were performed before and after treatment with mirabegron. Changes in video-urodynamic parameters, the need for other NLUTD therapy during follow-up, patient-reported side effects, and urinary incontinence were outcomes of interest. A total of 34 patients with NLUTD were included. All patients were on CIC and the median age was 13.1 years (IQR 15.9-10.3). Median follow-up was 31.4 months (IQR 57.4-11.4). Bladder compliance improved by 89.9%, from 14.9 to 28.3ml/cm H2O (p-value<0.001). Maximum cystometric capacity, end-filling detrusor pressure, volume at first detrusor overactivity, vesicoureteral reflux, and urinary incontinence significantly improved after mirabegron. The add-on therapy group showed more significant improvements in video-urodynamic outcomes compared to the monotherapy group. The median time of requiring other NLUTD therapy was 25.5 months (IQR 39.8-14.8). None of the included patients reported side effects. Mirabegron is an effective treatment for children with therapy-refractory NLUTD with an average efficacy of 2 years after which additional therapy is required. Despite the retrospective character of this study, our results confirm the beneficial effect of mirabegron in children with therapy-refractory NLUTD, in particular when mirabegron is used as add-on therapy in those with low-compliance bladders.