**2. Results**

There were 181 patients including 138 females and 43 males receiving urethral BoNT-A injections in this study. The mean age at injection was 59.7 ± 21.1 years old in women and 67.3 ± 14.1 years old in men, which was significant younger in the former (*p* = 0.003). Compared to men, women had a higher percentage of recurrent urinary tract infection (43% vs. 5%, *p* < 0.001) and history of receiving transurethral incision or resection of the bladder neck (TUIBN) (50% vs. 19%, *p* < 0.001), but a lower percentage of Parkinson's disease (1% vs. 14%, *p* = 0.003) and dementia (1% vs. 7%, *p* = 0.042). A total of 56% of men had received transurethral resection of the prostate (TURP). Detailed baseline characteristics and comorbidities stratified by gender are shown in Table 1.


**Table 1.** Baseline characteristics and comorbidities stratified by gender.

CKD: Chronic kidney disease; COPD: Chronic obstructive pulmonary disease; CVA: Cerebrovascular accident; UTI: Urinary tract infection; TURP: Transurethral Resection of Prostate; TUI-BN: Transurethral Incision or Resection of the Bladder Neck. \* Urethral sphincter dysfunction including dysfunctional voiding and poor relaxation of urethral sphincter.

Table 2 shows the baseline and post-injection VUDS parameters and the post-injection GRA in women with different types of voiding dysfunction. There were 61 women with DU and 77 with urethral sphincter dysfunctions in this study. A significantly lower rate of successful outcome was noted in women with DU compared to those with urethral sphincter dysfunction (56% vs. 74%, *p* = 0.024). Except for mild decrease of US, no obvious change of other VUDS parameters was detected in women diagnosed of DU. Increased

FSF (103.6 ± 60.5 to 125.3 ± 74.6 mL/s, *p* = 0.034) and decreased Pdet (54.7 ± 36.0 to 45.5 ± 33.9 cmH2O, *p* = 0.034), as well as BOOI (41.8 ± 37.5 to 31.6 ± 35.9, *p* = 0.010), were noted in women with urethral sphincter dysfunction. In the male cohort, there were 43 patients receiving urethral sphincter BoNT-A injection. Among them, 17 men were diagnosed with DU and 26 with urethral sphincter dysfunction (Table 3). A significantly lower rate of successful outcome was noted in men with DU compared to those with urethral sphincter dysfunction (36% vs. 73%, *p* = 0.014). Although there was some dissimilarity in clinical and VUDS parameters, no difference in treatment response rate after urethral sphincter BoNT-A injection was found among different subtypes of urethral sphincter dysfunction (Appendix A Table A1).

Univariable logistic regression analysis for predictors of successful outcome revealed that history of recurrent urinary tract infection (UTI) (OR = 2.37, *p* = 0.024) and VE (OR = 1.02, *p* < 0.001) were positively correlated with the outcome; whereas DU (OR = 0.37, *p* = 0.002), history of hypertension (OR = 0.50, *p* = 0.026) and FS (OR = 1.00, *p* = 0.036) in VUDS correlated with the outcome negatively (Table 4). After adjusting for age and gender, history of recurrent UTI and VE were positive predictors for a successful outcome with odds ratios of 3.82 (95% confidence interval: 1.58–9.22, *p* = 0.003) and 1.02 (95% confidence interval: 1.01–1.03, *p* = 0.004), respectively. On the other hand, DU was a negative predictor with an odds ratio of 0.46 (95% confidence interval: 0.21–0.99, *p* = 0.047) in the multivariable logistic regression analysis.

**Table 2.** Baseline and post-injection urodynamic parameters and the post-injection global response assessment in female patients with different types of voiding dysfunction.


BOOI: bladder outlet obstruction index; BVE: bladder voiding efficiency; DO: detrusor overactivity; DU: detrusor underactivity; FS: full sensation; FSF: first sensation of filling; Pdet: maximal detrusor pressure; PVR: post-void residual volume; Qmax: maximal uroflow rate; SD: standard deviation; US: urge sensation; VV: voided volume; VUDS: videourodynamic study. a Successful outcome was defined as a global response assessment greater than mildly improved (score - 2). b Difference between detrusor underactivity and urethral sphincter dysfunction. \* Urethral sphincter dysfunction including dysfunctional voiding and poor relaxation of urethral sphincter.


**Table 3.** Baseline and post-injection urodynamic parameters and the post-injection global response assessment in male patients with different types of voiding dysfunction.

BOOI: bladder outlet obstruction index; BVE: bladder voiding efficiency; DO: detrusor overactivity; DU: detrusor underactivity; FS: full sensation; FSF: first sensation of filling; Pdet: maximal detrusor pressure; PVR: post-void residual volume; Qmax: maximal uroflow rate; SD: standard deviation; US: urge sensation; VV: voided volume; VUDS: videourodynamic study. a Successful outcome was defined as a global response assessment greater than mildly improved (score - 2). b Difference between detrusor underactivity and urethral sphincter dysfunction. \*Urethralsphincterdysfunctionincludingdysfunctionalvoidingandpoorrelaxationofurethralsphincter.

**Table 4.** Logistic regression analysis for predictors of successful outcomes after urethral sphincteric botulinum toxin A injection.


BOOI: bladder outlet obstruction index; BVE: bladder voiding efficiency; CAD: Coronary artery disease; CI: confidence interval; CKD: Chronic kidney disease; COPD: Chronic obstructive pulmonary disease; CVA: Cerebrovascular accident; DM: diabetes mellitus; DO: detrusor overactivity; DU: detrusor underactivity; FS: full sensation; FSF: first sensation of filling; HTN: hypertension; PD: Parkinson's disease; PVR: post-void residual volume; Qmax: maximal uroflow rate; UTI: Urinary tract infection; TURP: Transurethral Resection of Prostate; TUI-BN: Transurethral Incision or Resection of the Bladder Neck; US: urge sensation; VUDS: videourodynamic study.
