IncobotulinumtoxinA vs OnabotulimuntoxinA for Treatment of Overactive Bladder Syndrome: A Randomized Single-Blinded Non-Inferiority Trial

INTRODUCTION: Overactive bladder significantly impacts quality of life in approximately 17% of the general population, and many of these women experience symptoms of urgency urinary incontinence. Treatment options range from conservative therapies with dietary and behavioral modifications to advanced therapies, such as sacroneuromodulation and intradetrusor injections of onabotulinumtoxinA. Multiple formulations of botulinum toxin are available for a wide range of indications. Only onabotulinumtoxinA is currently approved by the Food and Drug Administration for treatment of overactive bladder. IncobotulinumtoxinA, a highly purified form of botulinum toxin A, has a similar efficacy and safety profile as onabotulinumtoxinA in other injection sites. It can be stored at room temperature and is cheaper than onabotulinumtoxinA. No studies exist comparing incobotulinumtoxinA to onabotulinumtoxinA for treatment of idiopathic overactive bladder syndrome. OBJECTIVE: The objective of this study is to compare the efficacy of incobotulinumtoxinA to onabotulinumtoxinA for treatment of idiopathic overactive bladder syndrome. METHODS: This study is a single-blinded, randomized, non-inferiority trial. All patients 18 years of age or older who were scheduled for intradetrusor onabotulinumtoxinA in the urogynecology clinic between May 2023 and June 2024 were screened for their eligibility. Patients who met inclusion criteria were offered enrollment. Participants were randomized to receive intradetrusor injection of either 100 units of incobotulinumtoxinA or 100 units of onabotulinumtoxinA. The primary outcome was measured as a change in the mean number of urgency urinary incontinence episodes from baseline to 2–6 weeks after the procedure. The non-inferiority limit of −1 was adopted. Secondary outcomes included a total number of daytime and nighttime voids, the Overactive Bladder Questionnaire, and the Patient Global Impression of Severity and Improvement scores. RESULTS: Data from 59 participants was analyzed (29 in incobotulinumtoxinA, 30 in onabotulinumtoxinA). The majority of the participants were between 40 and 59 years of age and postmenopausal. There were significantly more postmenopausal participants in the onabotulinumtoxinA group (16 incobotulinumtoxinA vs 26 onabotulinumtoxinA, p=0.01). All other demographics were similar between the groups. Both groups were noted to be ethnically diverse, with the most common ethnic groups being White (38% incobotulinumtoxinA, 56% onabotulinumtoxinA) and Black (31% incobotulinumtoxinA, 22% onabotulinumtoxinA). Comparing incobotulinumtoxinA to onabotulinumtoxinA, the difference in mean reduction of urgency urinary incontinence episodes from baseline to 2–6 weeks after treatment was 0.41 (90% confidence interval −0.88 to 1.71), meeting the predetermined non-inferiority margin of being above −1. Secondary analyses showed two outcomes with significant difference between the two groups. A larger decrease in number of daytime voids from baseline was noted in the onabotulinumtoxinA group (2.54±2.00 incobotulinumtoxinA vs 3.00±4.74 onabotulinumtoxinA, p=0.05). The Patient Global Impression of Improvement scores showed higher improvement in the incobotulinumtoxinA group (2.57±1.45 incobotulinumtoxinA vs 1.93±0.83 onabotulinumtoxinA, p=0.04). There was no statistically significant difference between adverse events in the two groups. CONCLUSIONS: In participants with idiopathic overactive bladder, incobotulinumtoxinA was not inferior to onabotulinumtoxinA in decreasing urgency urinary incontinence episodes in short-term follow-up with comparable adverse effects. IncobotulinumtoxinA offers a safe, purer, cheaper, and more logistically convenient alternative with similar efficacy for patients with idiopathic overactive bladder symptoms.