The causes of incontinence following radical prostatectomy include urethral sphincter damage, alteration in bladder function (e.g. detrusor overactivity) or a combination of both. However, most would agree, that sphincteric incompetence is likely the predominant factor [11
]. Factors that have been associated with an increased risk for post-prostatectomy incontinence include: older age [5
], advanced stage [12
], and the presence of anastomotic stricture [5
]. While most patients experience transient incontinence after catheter removal, many studies report an achievement of urinary continence in the majority of patients that can take up to 2 years [5
], although in the majority this appears to occur within the first 6 months [13
]. There is some evidence that nerve sparing can improve continence rates [15
]. All our patients underwent an attempt at nerve sparing but we do not have the data regarding the number with attempted unilateral versus bilateral nerve sparing nor regarding the actual success of nerve sparing. Burkhard et al's data suggests there may not be significant difference in continence outcome between bilateral and unilateral nerve sparing (1.3% vs. 3.4% incontinence rates, respectively) but there was a significant difference when compared to non-nerve sparing (13.7% rate of incontinence) [15
]. As such, our data needs to be considered in light of the nerve sparing approach and may not be generalizable to non-nerve sparing RRP.
Similar to other reports, our patients experienced a gradual improvement in their incontinence based on 1 hour pad testing such that by 16 weeks postoperatively, 2/3 of the patients had ≤1 g of leakage on their pad test consistent with being continent as per the ICS. By 30 weeks 85% of patients fit in this category and by 54 weeks, 91%. A study by Donnellan et al that is similar to ours in that 1 hour pad testing was performed, showed almost the identical results with 64% objectively dry at 3 months, 72% at 6 months and 84% at 1 year [13
]. In our study, all patients were instructed on pelvic floor exercises pre-operatively as well as post-operatively and this has been shown by some to hasten continence recovery [16
] although not by others [17
]. We do not have data regarding the compliance with the exercises which is a limitation of the study and furthermore we do not have a comparison group that was not instructed. Filocam et al's study of pelvic floor exercises versus no intervention showed a similar trend in continence recovery as our study with the greatest improvement in incontinence occurring within the first 6 months of surgery [16
]. In fact 74% of patients performing pelvic floor exercises were considered continent at 3 months while 30% of patients who did not perform the exercises were continent. Our continence rates fall somewhere in between these 2 points and perhaps reflect the fact that our patients did not have as comprehensive teaching in pelvic floor exercises as their patients. It is noteworthy that while pelvic floor exercises may have benefit with respect to continence recovery time, they do not appear to influence continence rates at 1 year or beyond [16
We did not incorporate a patient estimate of incontinence severity or pad usage at home because the purpose of this study was to specifically use an objective measure of incontinence with the 1 hr pad test. Quantitative measurement of urine leakage was introduced by James et al [18
] and ultimately developed into the 1 hour pad test by Bates et al [10
]. This was subsequently endorsed by the International Continence Society in 1988 [9
]. Studies have been inconclusive as to the patient's ability to estimate incontinence severity with some claiming a good correlation between pad usage and degree of incontinence [6
], while others showed a poor correlation [3
]. There are a number of variables that factor into this equation including: variable pad size, degree of wetness, and patient tolerability of wetness resulting in more/less frequent pad changes. Furthermore, some patients may prefer not to use pads at all yet still experience some incontinence for which they change their underwear/clothes; they would be categorized as continent on the basis of lack of pad use if that is the definition of continence, which it often is in studies. But of course they are not technically continent. What is clear is that continence rates vary significantly based on the use of different definitions of incontinence and the method of assessment (e.g. patient reported versus physician reported) [2
]. Some have argued that with respect to quality of life, simply asking the patient about incontinence and the subjective severity may be as good as or better than using a pad test to quantify incontinence [20
]. However, we would argue that patients experience incontinence differently and what might be considered mild, non-problematic incontinence by one patient may not be the same to another patient. In one study, while 63% of patients continued to be incontinent 6 months postoperatively with a median leakage of 46 mL on 24 hour pad testing, 71% of patients found their incontinence to be of no or only a minor problem on quality of life assessment [3
]. The authors argue, therefore, that the degree of bother may be the best indicator of severity of incontinence. However, we would argue that the attitude toward incontinence is different for different patients. Hence an objective measure of incontinence severity is needed. This is evidenced by the fact that some patients insist on frequent pad changes for minimal incontinence while others may not even wear a pad despite significant incontinence. Thus simply relying on patient reported pad usage can potentially over- or underestimate the actual severity of the incontinence. At least with pad weighing, one gets an absolute value as to the degree of incontinence. However, we do agree that before any aggressive intervention for incontinence, the degree of bother must be taken into account; there would be no indication for surgical intervention if the patient is not bothered by his incontinence. Our study, therefore, is limited by this lack of subjective assessment of the degree of bother but nevertheless does provide important objective data.
Whether a 1-hour pad test is as reliable as a more prolonged pad test such as a 24 or 48 hour test is still a matter of debate, and while some have argued that a 24 hour test is more useful [21
], the 1-hour pad test does require less patient compliance because it can be done at a clinic visit and does not burden the patient with home instructions that can easily be misinterpreted or forgotten. It has been demonstrated that the longer the pad test is kept the less compliant are patients [23
]. Our pad test was done following the consumption of a standard volume of fluid but bladder volumes were not standardized. It is known that the reliability of the 1 hour pad test can be increased when bladder volumes are standardized [24
] and therefore this is another limitation of our study. The limit of 1 g of leakage that we used as an indicator of continence is based on the results in women since to our knowledge there is no data on this in men. However, Moore et al, using the 24 hour pad test in men who considered themselves continent prior to RRP, found an upper limit of 8 g/24 hr as being a reliable indicator of continence and this is generally considered the upper limit for continence in women on a 24 hour pad test as well [25
]. As such we believe that the 1 g threshold for the 1 hr pad test is reasonable for men.
Our ultimate goal is to be able to use continence recovery time nomogram to help counsel patients as to the likelihood of achieving continence post-RRP. A prospective evaluation is underway looking at the predictive value of this nomogram. If it is determined at the 3 or 6 month time point that the likelihood of achieving continence is extremely low, the patient may opt for more aggressive treatment (e.g. artificial urinary sphincter, AUS) sooner rather than later which might allow for improved quality of life sooner rather than later. Currently, it is recommended that patients wait at least 6–12 months from their RRP before undergoing AUS placement [7
]. However, if our nomogram is accurate in its ability to predict the achievement/failure to achieve continence, then patients may make decisions regarding the timing of definitive intervention based upon the probability of recovery. This could translate into an improvement in quality of life sooner. Because surgical skill and technique are clearly important variables with respect to outcome [26
], it is probably best that surgeons review their own experience to perhaps devise a nomogram as we have done to be better able to counsel their patients regarding their incontinence.