Mirabegron and Intradetrusor Onabotulinumtoxina for Overactive Bladder in Parkinson's Disease: A Systematic Review...

To synthesize the evidence on the efficacy and safety of mirabegron and intradetrusor onabotulinumtoxinA (BoNT-A) as separate interventions for overactive bladder (OAB) in Parkinson's disease (PD).

A systematic review and meta-analysis with parallel synthesis of two distinct interventions was conducted of randomized and observational studies involving adults with idiopathic PD and OAB treated with mirabegron or BoNT-A. Primary outcomes included mean change in 24-h voiding frequency, nocturia, urgency, and incontinence. Secondary outcomes were postvoid residual (PVR) volume and adverse events. Pooled outcomes were reported as mean differences (MDs), representing the change in symptoms from baseline to follow-up; negative MDs indicate a reduction in symptom frequency.

No direct head-to-head comparative trials of mirabegron versus BoNT-A were identified; however, eight single-arm pre-post studies met the inclusion criteria. Pooled analysis showed reductions in 24-h urinary frequency (MD -4.48; 95% CI -8.45 to -0.52), nocturia (MD -1.36; 95% CI -2.68 to -0.05), urgency (MD -2.68; 95% CI -7.08 to 1.72), and incontinence (MD -1.24; 95% CI -1.98 to -0.50). BoNT-A was associated with a mean increase in PVR (+43 mL), whereas mirabegron was associated with minimal change (+3 mL). Adverse events were generally mild with mirabegron (e.g., dizziness, constipation, hypertension), whereas BoNT-A was associated with transient urinary retention and urinary tract infection. The certainty of evidence across outcomes was low to moderate and therefore should be interpreted with caution.

Currently, no studies have directly compared the benefits of mirabegron versus BoNT-A. Available study data confirm that both mirabegron and BoNT-A were associated with directional reductions in several OAB symptoms in PD. However, urgency and most subgroup analyses did not reach statistical significance. The overall certainty of evidence was low to moderate due to small sample sizes, heterogeneity, and short follow-up. These findings are hypothesis-generating and should be confirmed in larger, randomized controlled trials with longer follow-up and ideally comparing effects head-to-head. PROSPERO Registration: CRD420251181682.