Predictors for adverse events following intravesical botulinum toxin injections in men.

[INTRODUCTION] Intravesical botulinum toxin A (BTX-A) has been long established as treatment for overactive bladder and neurogenic bladder dysfunction. However, most published data are reported among a female cohort. Adverse events such as intermittent self-catheterization (ISC) and urinary tract infections (UTIs) play a large role in discontinuation of therapy. There is currently limited information regarding predictive factors to appropriately counsel male patients.

[MATERIALS AND METHODS] We retrospectively collected data on male patients undergoing their first intravesical BTX-A therapy from January 2016 to July 2021 in two high-volume centers. Data included demographics, past medical and surgical history, and urodynamic parameters. Patients were excluded if they had a long-term catheter or ISC before initiation of therapy.

[RESULTS] A total of 69 men were included in the study with a median age of 66 years. There were 18 patients with neurogenic bladder dysfunction. Thirty men had urge incontinence secondary to radical prostatectomy or bladder outflow surgery. Overall rates of ISC were 43.5%. Predictors for ISC included a baseline postvoid residual (PVR) ≥ 50 mL (odds ratio [OR]: 4.2, 95% confidence interval [CI]: 1.36-13.03, p = 0.01), BTX-A dose >100 units (OR: 4.2, 95% CI: 1.36-13.0, p = 0.01). Stress urinary incontinence was protective against ISC (OR: 0.20, 95% CI: 0.04-1.00, p = 0.049) as well as history of prostatectomy/bladder outflow obstruction (BOO) surgery (OR: 0.16, 95% CI: 0.05-0.47, p < 0.001). A multivariable logistic regression model with these factors yielded a c-statistic of 0.80 (optimism-adjusted = 0.75). An enlarged prostate was the only predictor for UTI among our male cohort (OR: 8.0, 95% CI: 2.03-31.5, p = 0.003).

[CONCLUSIONS] This is the first study assessing risk factors of adverse events among men following BTX-A injection. High PVR and BTX-A dose of >100U were predictors of requiring ISC after BTX-A. Stress incontinence, previous radical prostatectomy, and BOO surgery were all protective against needing ISC post-BTX-A. An enlarged prostate was associated with development of UTI. These factors can be used to assist in counseling male patients regarding their risk of ISC and UTI.