Clinical Outcomes and Retreatment Pathways Following Intradetrusor OnabotulinumtoxinA in Women with Refractory Idiopathic Overactive Bladder

Background/Objective: Intradetrusor onabotulinumtoxinA is an established treatment for refractory idiopathic overactive bladder (OAB); however, data on predictors of treatment response and patient management after the initial injection are limited. This study evaluated the clinical outcomes, safety, factors associated with treatment failure, and retreatment pathways following intradetrusor onabotulinumtoxinA in women with refractory idiopathic OAB. Methods: This retrospective cohort study included 41 women with refractory idiopathic OAB treated with 100 U intradetrusor onabotulinumtoxinA between November 2022 and January 2026. Efficacy was assessed using 3-day bladder diaries, validated patient-reported outcome measures (UDI-6, IIQ-7, and OAB-V8), and the Treatment Benefit Scale (TBS). Safety outcomes, factors associated with treatment failure, retreatment preferences, and subsequent management strategies were analyzed. Results: Significant improvements were observed in daytime frequency, urgency episodes, urgency urinary incontinence episodes, and validated patient-reported outcome measures (all p < 0.001). Treatment success according to the TBS was achieved in 68.3% and 46.3% of patients at 12 and 24 weeks, respectively. Diffuse bladder trabeculation was independently associated with treatment failure at 12 weeks (aOR 11.90, 95% CI 1.99–71.14; p = 0.007), whereas no significant independent association was observed at 24 weeks. Urinary tract infection occurred in 19.5% of patients, and temporary clean intermittent catheterization was required in one patient (2.4%). By postoperative week 24, 53.7% of patients declined repeat treatment, most commonly because of inadequate symptom improvement (77.3%). Among those declining reinjection, 59.1% resumed or continued pharmacological therapy. Conclusions: Intradetrusor injection of 100 U onabotulinumtoxinA was associated with significant improvement and acceptable safety in women with refractory idiopathic OAB. Diffuse bladder trabeculation may help identify patients at risk of poor treatment response, warranting further validation in larger patient cohorts. Documenting retreatment decisions and management provides real-world evidence that may support long-term counseling and decision-making.