Functional results of orthotopic ileal neobladders (iONs) vary depending on the surgical technique performed. Standardization in reporting continence outcomes is lacking, as well as objective measurements with urodynamic assessment remains an historical issue. The aim of this pooled series was to identify urodynamic predictors of daytime and night-time urinary continence for robotic and open iONs performed at two high-volume centres.

Between June 2017 and December 2020 two prospective, board-approved, radical cystectomy dataset were matched and queried for “iON” “and “urodynamic evaluation” (n=66). Baseline data and complete urodynamic profile including uroflowmetry, cystometry, compliance, presence of residual peristaltic activity, abdominal leak point pressures (ALPP) as functional outcomes assessed by daytime and night-time continence (defined as the use of 0-1 pad) were reported. Descriptive analyses were used. Frequencies and proportions were reported for categorical variables while medians and interquartile ranges (IQRs) were reported for continuously coded variables. Daytime and nigh-time urinary incontinence probabilities were computed by Kaplan-Meier curves and compared for baseline and urodynamic variables with the log-rank test, respectively.  Cox regression analyses were used to identify predictors of daytime and nightime urinary continence. For all analyses, a two-sided p<0.05 was considered significant.

Overall, at a median follow-up of 11 months (IQR 7-19.5) 66 patients achieved a complete urodynamic evaluation. On Kaplan-Meier analysis, male patients achieved significantly higher rates of daytime urinary continence (Fig.1; p=0.03) while the presence of neobladder residual peristaltic activity and a maximal bladder pressure> 50 cmH20 were associated to significantly higher probabilities of night-time urinary incontinence (both p<0.05). At univariable Cox regression analysis male gender (HR 0.47, 95% CI 0.23-0.95; p=0.03) was predictor of daytime urinary continence while diabetes was predictor of night-time urinary continence (HR 5.77, 95% CI 1.24-26.7; p=0.02). At multivariable Cox regression analysis, neobladder residual peristaltic activity, (HR 0.37, 95% CI 0.14-0.99; p=0.049) and maximal neobladder pressure >50cmH20 (HR 8.22, 95% CI 2-33.7; p=0.003) were all independent predictors of night-time urinary incontinence.

Basing on our data, the only predictor of daytime urinary continence appeared to be male gender: interestingly, at univariable regression analysis BMI, age and surgical approach were not found predictor of daytime or night-time urinary continence. Diabetes, which affected 3% of our cohort, was found the only predictor of night-time urinary continence, but since it affected only 2 patients, further studies are needed to validate this correlation. However, no independent predictors of day-time urinary continence were found at the multivariable analysis, whilst neobladder residual peristaltic activity and maximal neobladder pressure > 50 cmH2O were found independent predictors of night-time urinary incontinence, hence evaluating and treating these aspects could improve patients’ dryness and quality of life.

According to our data, males seemed to reach better continence rates than females, regardless to BMI, age and surgical approach. Hyperactivity and maximal bladder pressures>50 cmH20 at urodynamic evaluation are independent predictors of nocturnal urinary continence in both open and robotic iON. Medical treatment of increased pouch activity secondary to bowel peristalsis may enhance the night-time continence rate.

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