Persistent urinary incontinence (UI) after radical prostatectomy (RP) is a significant side effect of a widely performed operation. While UI has a strong and sustained influence on a patient’s overall quality of life (QoL), it can have a complex, multidimensional clinical appearance. For example, many continent patients still rely on absorbent security pads, while others do not mind or even notice wet pads. At the other end of the spectrum, others can be devastated by minimal urinary leakage. Many in this latter group change pads multiple times per day though they are nearly dry. Furthermore, there are various types and sizes of pads. With such inconsistencies in mind, it is difficult to report, let alone assesses or compares, UI using existing methods.

In an attempt to make such a comparison, questionnaires have been developed to multidimensionally assess UI and to more accurately report and measure the true value of urinary continence [1]. More exhaustive questionnaires, such as the University of California, Los Angeles Prostate Cancer Index (UCLA-PCI) or the Functional Assessment of Cancer Therapy – Prostate, are promising, but they are subjective and lack exact quantitative cutoff values (COVs) [2].

One widely used questionnaire is known as the Expanded Prostate Cancer Composite (EPIC) [3], an expansion of the original UCLA-PCI [2] that was developed to assess the presence of bothersome symptomatology after prostate cancer treatment. A section of this scoring system is solely dedicated to the assessment of urinary problems and is composed of 12 questions that address continence, as well as hematuria, dysuria, and other voiding problems. In addition to requiring objective answers (such as the number of pads used daily), the EPIC also allows for subjective answers, such as “occasional” and “frequent.” In developing an objective method to better assess UI post-RP, it is also important to recognize that many existing assessments such as the EPIC also lack a clear, uniform definition that differentiates continence from incontinence. This, in turn, can also restrict the objectivity of these assessments.

Again, having uniform definitions and criteria would greatly facilitate the comparison of various patient populations and experimental trials. As quantitative assessments typically facilitate objectivity, we sought to establish a standardized definition of continence based on a quantitative COV. Between 2004 and 2013, our institution prospectively collected functional and oncological data (including the EPIC score) from patients undergoing RP. Therefore, the aim of our investigation was to define a COV for the EPIC score by assessing the functional data of our long-term RP cohort.

A total of 239 patients with a median age of 63 years old (interquartile range [IQR], 59–66 years) participated in the study (Table 1). The median follow-up time was 48 months (IQR, 30–78 months). The median preoperative EPIC-UI score was 100 points (IQR, 91.75–100 points). One year postoperatively, the EPIC-UI score decreased to 85.5 points (IQR, 58.5–100 points).

Several methods have been developed for determining and documenting UI, and they range from simple to highly complex. However, no existing method accurately characterizes the multidimensional nature of UI. We surmised that an ideal method would be (1) objective, (2) easy to understand for the patient, (3) easy to collect as a healthcare provider, and (4) easy to interpret accurately. We consider these criteria to be equally important and, to our knowledge, such an ideal test does not yet exist. Therefore, our aim with this paper was to demonstrate our attempt at developing a quantitative COV based on an existing exam: the EPIC-UD.

Thus far, the gold standard for assessing UI has been simply to ask a patient regarding his or her use of absorbent pads for urine leakage. The use of such a pad after RP would imply some degree of persistent UI. While this method fulfills 3 of the 4 criteria listed above, it disregards the fact that this assessment could be strictly or liberally interpreted. For instance, many physicians consider a patient to be continent even if that patient occasionally relies on a security pad [4]. Additionally, the need for a pad is not well-defined, which negatively affects the accuracy of answers to this question. For example, an incontinent patient who loses urine weekly and refuses to wear pads could hardly be accurately assessed using this criterion. Conversely, a careful man who hardly ever loses urine, but changes pads multiple times daily to maintain his hygiene, may be misinterpreted to be reliant on pads when he is actually not. Therefore, there is a need for standardized criteria that accurately classify incontinence as well as its management.

To instill a degree of objectivity, some authors have weighed patients’ pads before and after having patients perform several standardized exercises [5,6]. However, such an approach is likely to be too cumbersome for daily clinical practice. This is further exacerbated by the lack of a routine assessment at all follow-up visit. Despite such drawbacks, such questionnaires have the potential to provide accurate clinical data even if they are not the easiest or most practical to implement. In this study, we present an EPIC score-based COV for urinary continence. These 4 questions solely addressing urinary continence were utilized to generate to a sub-score known as the EPIC-UI.

In this paper, we sought to determine an objective COV based on the EPIC scoring system. Our calculations identified a COV of 85 (UI-85) for continence. To assess the clinical relevance of this COV, we compared it against the binary definition of continence (i.e., pad or no-pad) as well as to QoL. In these calculations, the UI-85 was strongly correlated with QoL; this correlation was stronger than that between QoL and the binary definition of continence.

Furthermore, we applied the UI-85 to our cohort of RP patients. While the cumulative continence rates were similar for both the UI-85 and the binary definition (52.5% and 59.7%, respectively), the median time to regaining continence was longer using the UI-85 (12 months vs. 9 months) for the same cohort. Hence, it appears that the UI-85 is a more sensitive and nuanced tool for describing postoperative continence rehabilitation, as it could detect slight increases in continence between months 9 and 12, whereas the binary definition plateaued earlier.

We also analyzed and compared the functional outcomes of our cohort. The percentage of men with EPIC-UI scores >85 at different time points demonstrated a high degree of similarity to the percentage of men who reported that they were “satisfied” with their QoL. This further corroborates the clinical relevance of the UI-85. We recognize that there are many different ways of measuring continence. For instance, weighing pads after predefined exercises is a relatively simple way of doing so. However, it is resource-intensive for both patients and their physicians. In contrast, the EPIC-UI can easily be extracted from the widely used EPIC score, making it an uncomplicated tool for monitoring continence over time or comparing the urinary continence between different cohorts.

Advances in operative techniques have done little to alleviate the doubt surrounding the impact of these approaches and technologies on UI [7]. Some trials have demonstrated better recovery of early incontinence (3–6 months postoperatively) following robotic RP, whereas other trials have suggested the opposite [8-10]. While the achievement and quality of early continence are important to understand, the majority of RP patients typically have a long life expectancy, making the analysis of long-term continence (more than 6 months postoperatively) outcomes dramatically more important and more clinically relevant.

While the results in our cohort only differed by 1.9% at the 10-year time-point, our Kaplan-Meier curves revealed a faster rate of increase of continence using the no-pad definition than when the UI-85 was used. At 2 years postoperatively, the plateau for the no-pad definition was reached, whereas continence levels per UI-85 plateaued after 3 years postoperatively. Thus, the EPIC-UI COV of 85 (i.e., the UI-85) appears to represent a more accurate and nuanced tool for monitoring postoperative continence.

When applying the UI-85, it is important to recognize that some men will eventually demonstrate slight UI. Hence, the UI-85 is not completely equivalent to no-pad. Nonetheless, our calculations showed that patients with an EPIC-UI > 85 were more likely to be satisfied with their degree of urinary continence. Over a several-year timeframe, it is possible that patients may accept a slight degree of incontinence, potentially leading to a bias (for e.g., reporting better outcomes despite unchanged continence or incontinence). We attempted to account for this problem by basing our calculations on data no older than the 1-year postoperative period, as practically, RP patients are less likely to enter the mental state of resignation at 1 year than at a later follow-up time.

Another consideration in the broader milieu of urinary continence is that the impact of nerve-sparing prostatectomy on urinary continence is still unclear and remains a matter of ongoing discussion [11-17]. In our cohort, only 39 patients who completed the EPIC questionnaire at 1 year postoperatively did not undergo nerve-sparing surgery. Furthermore, these patients were statistically significantly older and had a higher tumor burden, both of which could have contributed to a substantial amount of bias if the ROC calculations for COVs had been performed for nerve-sparing and non–nerve-sparing groups separately. Hence, to generate a universally applicable definition, patients with and without nerve-sparing RP were collectively included in the study.

In conclusion, the COV of the EPIC-UI for continence was found to be 85 (the UI-85). The UI-85 represents a nuanced and straightforward tool to monitor and compare urinary continence between different time points and cohorts in a multidimensional and objective manner.