Efficacy of 200 IU OnabotulinumtoxinA (Botulinum Toxin Type A) in Patients with Idiopathic Overactive Bladder Resistant to Anticholinergic Treatment: A Retrospective Analysis

Objective: This study aimed to evaluate the efficacy and safety of 200 IU of onabotulinumtoxinA in patients with idiopathic overactive bladder (OAB) and urinary incontinence who had previously shown no response to anticholinergic treatment. This study also sought to examine the impact of a reduction in bladder wall thickness (BWT) on treatment outcomes. Material and Methods: A retrospective analysis was conducted on patients treated between January 2016 and June 2022. Baseline symptoms and quality of life data were compared with those obtained six months post-treatment. Baseline ultrasound (US)-measured post-void residual urine (PVR) and BWT were recorded. Patients with a history of neurological disorders, anticholinergic-naive patients, those diagnosed with bladder cancer, and those with bladder outlet obstruction were excluded. Results: This study included 60 patients (41 females and 19 males) with a mean age of 36.05 years. At six months, statistically significant improvements were observed in OAB symptoms, including average urination frequency, nocturia, and incontinence episodes (p<0.001). Noteworthy reductions in BWT were also observed (median and mean values decreased from 5.25 mm and 5.22 mm to 4.60 mm and 4.66 mm, respectively). Two patients experienced urinary tract infections, and none required clean intermittent catheterization (CIC). Conclusions: OnabotulinumtoxinA demonstrated substantial improvements in symptoms and patient-reported outcomes in patients who previously failed to respond to anticholinergic treatment. BWT reduction may be a valuable parameter for evaluating treatment success, although further research with statistical analysis is necessary. Keywords: botulinum toxin type A, onabotulinumtoxinA, overactive bladder, randomized controlled trial, urinary incontinence, bladder wall thickness