Study design, materials and methods
This prospective observational study was conducted at Botkin Hospital from September 2024 to January 2025 and included 30 female patients with DO-related urinary incontinence who received 500 units of BoNT-A-ABO. Inclusion criteria were refractory symptoms to conservative management and post-void residual volume ≤100 ml. Patients with recurrent bacterial cystitis, absence of prior effective conservative therapy, or post-void residual volume >100 ml were excluded. Patients with positive preoperative urine cultures received antibiotics according to sensitivity results both before and after surgery. Preoperative and postoperative (at 1-month follow-up) assessments included comprehensive urodynamic studies (cystometry, uroflowmetry), cystoscopy, urine culture, ultrasound assessment of residual urine, and the Overactive Bladder questionnaire short form (OAB-q SF). Statistical analysis was performed using the latest available versions of Jamovi and ChatGPT 4.5 (OpenAI). Power calculations indicated that a sample size of 30 patients provides adequate statistical power (80%) to detect clinically meaningful differences with α set at 0.05.
Results
Significant clinical improvements were observed following BoNT-A-ABO injections. Patients reported significant decreases in the severity of their symptoms, specifically:
• Urgency discomfort decreased from moderate/severe (mean score ~3.7) to mild (~0.9), an improvement of approximately 76%.
• Episodes of urgency without prior warning decreased from moderate/severe (~3.6) to mild (~0.9), an improvement of approximately 75%.
• Urge urinary incontinence episodes decreased from moderate (~3.0) to mild (~0.9), an improvement of approximately 68%.
• Frequency of nocturnal awakenings due to voiding decreased from moderate (~3.0) to mild (~1.0), an improvement of approximately 65%.
• Night-time awakenings caused by urgency decreased from moderate (~3.2) to mild (~1.0), an improvement of approximately 69%.
• Episodes of urgency-related leakage decreased from moderate (~3.3) to mild (~1.2), an improvement of approximately 63%.
These improvements were statistically significant (p<0.001 for all comparisons). Urodynamic parameters demonstrated significant reductions in Qmax decreased from 20.7±7.52 ml/s to median 11.30 ml/s [IQR: 8.50–15.80] and Qave decreased from 12.1±5.41 ml/s to median 5.65 ml/s [IQR: 4.40–9.27]. Additionally, daily pad usage reduced from 3.8±2.09 to median 1 [0;2]. Microbiological analysis indicated a decrease in bacteriuria prevalence from 50% preoperatively to 30.8% postoperatively, with E. coli being the predominant bacterium detected.
Interpretation of results
The study demonstrates significant symptomatic improvements following intradetrusor injections of BoNT-A-ABO, confirming its effectiveness in managing overactive bladder symptoms. However, the observed reductions in uroflowmetry parameters (Qmax and Qave) suggest a predictable decrease in detrusor contractility post-treatment, emphasizing the importance of careful monitoring of patients to avoid clinically significant urinary retention and elevated residual volumes. The postoperative decrease in bacteriuria prevalence is more likely a result of targeted antibiotic prophylaxis. Given that increased residual urine volume can predispose patients to bacterial growth and urinary tract infections, future studies should aim to define optimal antibiotic strategies and carefully evaluate the dosage of botulinum toxin units to prevent excessive residual urine volumes, thereby optimizing patient outcomes.