Long-term efficacy of Mirabegron-anticholinergic combination in paediatric neurogenic bladder.

Introduction: The Mirabegron-anticholinergic (MAC) combination has proven effective as a step-up strategy in managing paediatric neurogenic bladder following anticholinergic medication and botulinum toxin (BTX) therapy. This study assesses the long-term efficacy of MAC in children with neurogenic bladder.

Patients and methods: A retrospective chart review was conducted from 2015 to 2023, including consecutive paediatric patients receiving Mirabegron (25/50 mg) with an anticholinergic agent (solifenacin 16, tolterodine 7, oxybutynin 7, trospium 1). MAC was started where previous therapy had failed to control bladder pressures. The study cohort had a minimum of 2 years of videourodynamics (VUD) follow-up (2-7 years) and 3.5 years of symptomatic follow-up (2-7 years). All patients used CIC. Efficacy was determined from VUD data, symptom reports, and adverse events (AEs) with upper tract status. Statistical analysis used median values, Friedman's two-way analysis of variance by ranks and Chi-squared testing (p < 0.05).

Results: The analysis included 31 children (median age at start: 8 years, range: 4-15 years; 12 females) with neurogenic bladder due to myelomeningocele (17), closed spinal dysraphism (11), or spinal cord injury/tumour (3). A minimum of 8 weeks post-MAC therapy, significant improvements were observed in VUD parameters of: bladder capacity, compliance, and maximum detrusor pressure. These improvements were sustained at final VUD follow-up (median 33 months) in 21 patients (Summary Table). However, 9 patients who showed initial VUD improvement at median 5 months lost the effect by median 27 months, with 4 non-adherent patients and 5 with lower initial bladder compliance. Initial symptom improvement occurred in 25 patients, sustained for a median of 43 months (range: 23-85) in 19 patients. Adverse events were minimal (constipation, fatigue, and UTI reported in one patient each). No significant changes in blood pressure or upper tract status were observed.

Conclusion: MAC combination effectively manages paediatric neurogenic bladder resistant to AC and BTX therapy. The VUD benefits (present in 77.8 %) and symptom benefits (present in 61 %) are maintained and ongoing for a significant period (median 33 and 43 months respectively) when commenced before significant loss of compliance. MAC presents a promising long-term treatment option for the paediatric neurogenic bladder.