Reportedly, the urinary continence is stable up to 12 months after RP [2]. Hence, previous studies have addressed CRs within 1 year post-RARP. Only little data are available at more than 24 months follow-up for urinary continence. In the current study, the CRs were 78.77%, 79.96%, 79.51%, and 76.50% at 1, 2, 3, and 4 years after the surgery, respectively (Table 1). No significant differences were observed in the continence outcomes during the 4-year follow-up. Our results certified that one year after RARP was the stable continence period [17]. Few studies have evaluated the CRs after 12 months. Shao et al. reported that CR was 89.4% at 24 months after RARP, while Xylinas et al. reported that the 24-month urinary continence rate was 88% based on the no-pad definition [7,18]. Murphy et al. reported a 36-month urinary continence rate of 94.7% using the no-pad or safety pad definition [19]. Mandel et al. reported that CRs were 89.5% and 90.9% at 24 and 36 months after the surgery, respectively [20]. The CR of the current study was 76.50% at 48 months after RARP, which has been the longest follow-up on the topic to date.
A large number of studies have evaluated the predictors of urinary continence within 1 year after surgery. These studies either included a relatively small number of patients or had a discontinuous follow-up. To the best of our knowledge, this is the first study to evaluate the predictors of continence from 1–48 months after RARP in a large sample.
In the current cohort, the CRs were 40.62%, 60.92%, 71.38%, and 78.77% at 1, 3, 6 and 12 months after RARP, respectively (Table 1). These results were in agreement with those from the recent study by Honda et al. that revealed CRs at 1, 3, and 6 months as 40.7%, 63.0%, and 73.1%, respectively [14]. The definition of postoperative urinary continence varied among several studies. Hitherto, there is no consensus on UI post-RP [21]. Herein, we selected the most stringent definition of incontinence: any leakage of urine. Reportedly, the continence rate one year after RARP is 69–97% [1,22]. The overall continence rate in this study was 78.77% at 12 months, without the usage of any pad. Although it is not excellent, it is within the average range.
To identify the predictive factors, urinary continence was divided into two categories: early continence (<3 months) and late continence (>12 months) [16].
In general, PLND was selectively performed for sampling purposes in intermediate- and high-risk patients [15]. One month after the surgery, PLND in the continence group occurred in 121 patients (45.83%), while it occurred in 217 patients in the incontinence group (56.22%) (P<0.05). Three months post-surgery, no significant differences were detected in both groups. The logistic analysis showed that PLND was a significant independent risk factor of early urinary continence at 1 month. Patients who had undergone PLND during surgery had a high risk of UI. Lymphadenectomy may give rise to transient damage to nerve vessel bundles (NVBs), which affected the recovery of urinary continence. However, with the recovery of body function, this impact declined gradually.
The current logistic analysis showed that NS was a significant independent protective factor of urinary continence at 1,3, and 6 months (Tables 5 and 6). These findings were in line with those from the study by Reeves et al., which found that avoiding damage to the nerves around the prostate improves urinary continence in the first 6 months after the surgery [23]. Michl et al. investigated long-term CRs (12 months) after RP and found a significant difference between the NS and non-NS groups [24]. The studies by Kadono et al. and Steineck et al. also indicated that NS is associated with urinary continence in the long-term [17,25]. The bias in the studies used for the analysis might have influenced the results. However, all the studies showed that NS during the surgery produced satisfactory postoperative continence outcomes.
Multiple studies have demonstrated that age is an independent risk factor for the return of continence at 1–12 months after RARP. Lavigueur-Blouin et al. evaluated the early continence after RARP [26]. It showed that advanced age was an independent predictor at 1 month. Kim et al. demonstrated that younger men could have an early recurrence of continence 3 months after RARP [27]. Greco et al. compared the continence outcomes of RARP in older men to those of the younger men [28]. The study showed that CRs at 1, 3, and 12 months were similar in the two groups; however, the older group had a significantly lower continence rate at 6 months. The results of these studies might partially be in agreement with those of our study. Shikanov et al. demonstrated that age is a predictor of continence return at 12 months after RARP, which is partially in accordance with the current results [29]. Our results show that advanced age is a significant risk factor of continence at 6, 12, and 24 months after the surgery (Tables 6 and 7). Men of advanced age had a high risk of UI. Older men have poor endothelial dysfunction, which affects the vascular supply of the NVBs. In addition, it is difficult to perform pelvic floor exercises (PLE) due to an age-related decrease in the mass of the skeletal muscle and neuronal plasticity [30]. These conditions might affect functional outcomes.
Interestingly, the optimal time to remove the indwelling catheter has not yet been determined. Conventionally, the urinary catheter was removed between 10 and 21 days postoperatively [31]. Typically, the catheter is removed 3 weeks after the operation in our center in order to ensure the healing of anastomosis. However, most patients returned home after the operation, and the indwelling catheter was removed at the local clinic. This leads to the inconsistency of catheter removal and the duration of indwelling catheter might be longer than expected.
Limitations
Nevertheless, the present study had some limitations. First, this was a retrospective study from a single institution, and surgeries were not performed by a single surgeon. Second, we did not analyze all variables due to the undocumented surgical steps of the procedure, variations in surgical experience, and differences in the pathological reports. Third, although a stringent definition of continence was applied, the conditions were reported by the patients rather than based on a quality questionnaire. Fourth, the potential bias in selecting the patients for the procedure might influence the results. In addition, data were missing as many patients were lost to follow-up. Despite these drawbacks, this study utilized a large sample size, and the survey of postoperative urinary continence was time-continuous.