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Impact of preoperative and postoperative membranous urethral length measured by 3 Tesla magnetic resonance imaging on urinary continence recovery after robotic-assisted radical prostatectomy.

Abstract

Introduction: We sought to investigate the impact of preoperative and postoperative membranous urethral length (MUL) on urinary continence using 3 Tesla (3T) magnetic resonance imaging (MRI) after robotic-assisted radical prostatectomy (RARP).

Methods: Between 2008 and 2013, 190 men with RARP underwent preoperative and postoperative MRI. Patients who received adjuvant radiotherapy or who were lost to followup were excluded, leaving 186 patients eligible for analysis. Preoperative MUL was estimated from the prostate apex to the penile bulb, while postoperative MUL was estimated from the bladder neck to penile bulb. Patients with no pads or protection were considered to have complete continence. Logistic regression analysis was used to identify predictors associated with urinary incontinence at six and 12 months.

Results: Age was commonly associated with urinary incontinence at six and 12 months. In addition, diabetes mellitus (DM) was another factor associated with urinary incontinence at 12 months. When adjusting these variables, preoperative MUL [less than or equal to]16 mm (95% confidence interval [CI] 1.01-1.14; p=0.022), postoperative MUL [less than or equal to]14 mm (95% CI 1.16-9.80; p=0.025) and percent change of MUL >18% (95% CI 1.17-7.23; p=0.021) were significantly associated with urinary incontinence at six months. However, at 12 months, preoperative MUL [less than or equal to]13.5 mm (95% CI 1.85-19.21; p=0.003) and postoperative MUL [less than or equal to]13 mm (95% CI 1.24-13.84; p=0.021) had impacts on urinary incontinence, but not percent change of MUL.

Conclusions: Preoperative and postoperative MUL were significantly associated with urinary continence recovery after RARP. Therefore, efforts to preserve MUL are highly recommended during surgery for optimal continence outcomes after RARP.

Introduction

Advances in robotic technology have enabled wide adoption of robotic-assisted radical prostatectomy (RARP) for treatment of prostate cancer. (1,2) Patel et al proposed ideal outcomes of RARP, called the "pentafecta," with the following criteria: concurrent achievement of urinary continence, sexual potency, no evidence of biochemical recurrence or postoperative complications, and negative surgical margins. (3,4) Of these factors, failure to achieve urinary continence after RARP is a major concern because it has a negative effect on quality of life and can cause psychological problems, such as anxiety or depression. (5) It is reported that approximately 4-22% of patients do not achieve urinary continence 12 months after RARP. (4,6-9)

Recent studies reported that preoperative clinical factors, anatomical characteristics, and surgical techniques are significantly associated with urinary incontinence after RARP. (1,7,10-15) Of these factors, membranous urethral length (MUL) is an important factor that directly correlates with the functional sphincter mechanism. The urethral sphincter mechanism is composed of an external striated sphincter and an internal smooth muscle layer that are both crucial to maintaining urethral closure pressure. (15) Preservation of maximal MUL is necessary to regain urinary continence, but it is affected by clinical factors, surgeon experience, and surgical technique.

The development of imaging modalities, such as magnetic resonance imaging (MRI) has enabled more accurate understanding of anatomical structure in the urethra. Previous studies showed that preservation of MUL is correlated with urinary continence after open or laparoscopic radical prostatectomy, and also demonstrated preoperative MUL as a significant predictor for recovery of urinary continence. (10,11,16) However, the roles of postoperative MUL, in addition to preoperative MUL and perioperative change in MUL with RARP have not been fully investigated. Therefore, we investigated the impact of preoperative and postoperative MUL measured with 3 Tesla (3T) MRI on urinary continence recovery after RARP.

Methods

Patient population

After receiving study approval from the institutional review board, prospectively maintained databases of 1332 patients who underwent RARP for prostate cancer between June 2008 and December 2013 were retrospectively reviewed. In our hospital, preoperative prostate MRI was routinely performed to assess local stage. A total of 190 patients who also underwent postoperative prostate MRI were identified. Three patients were excluded because they received adjuvant radiation therapy before postoperative prostate MRI and one patient was excluded for followup less than one year. No patients had evidence of local recurrence on postoperative prostate MRI and no patients received salvage radiation therapy. The mean time from preoperative prostate MRI to postoperative prostate MRI was 12.6 months.

Clinicopathological parameters

Patient demographics (age, height, weight), medical comorbidities, perioperative parameters (nerve preservation, operation time, estimated blood loss), and postoperative parameters (pathological stage, pathological Gleason score, positive surgical margin) were reviewed. Using a questionnaire during followup, patients reported urinary continence at one month, three months, six months, and 12 months after RARP. A five-point scale was used to assess continence grade.(11) Patients with Level 1 urinary continence (no pads or protection) were considered to have complete continence.

MUL was estimated in the midline sagittal plane cross-referenced to the coronal plane on T2-weight images (Fig. 1). On preoperative MRI, MUL was defined as a distance from the apex of prostate to the urethra at the level of the penile bulb (Figs. 1A, 1B). On postoperative MRI, MUL was defined as a distance from the bladder neck to the urethra at the level of the penile bulb (Figs. 1C, 1D). The percent change of MUL was calculated by dividing the difference between preoperative and postoperative MUL by preoperative MUL.

Statistical analysis

Continuous variables were expressed as mean (standard deviation, range) and were compared using the independent t-test. Categorical variables were shown as absolute values (percentage) and compared using the chi-squared test or Fisher's exact test. Univariate and multivariate logistic regression analyses were performed to determine predictive factors associated with urinary incontinence six months and 12 months after RARP. To further evaluate the impact of preoperative, postoperative, and percent change of MUL on urinary continence, multivariate logistic regression analyses were employed with adjustment of the variables (age at six months, age and diabetes mellitus [DM] at 12 months) associated with urinary incontinence after RARP. All statistical analyses were performed using IBM SPSS version 20.0 (IBM Corp. Armonk, NY, U.S.). Two-sided pvalues <0.05 were considered statistically significant.

Results

The baseline clinical and pathological characteristics of 186 patients who underwent RARP are summarized in Table 1. At 12 months after RARP, urinary continence was restored in 165 (88.7%) patients. When patients were divided into two groups (continence (+) versus continence (-)) according to urinary continence 12 months after RARP, mean age at surgery (64.0 vs. 68.5 years), preoperative MUL (15.9 vs. 14.9 mm), and postoperative MUL (13.9 vs. 13.0 mm) were significantly different (each p<0.05).

Serial changes in urinary continence recovery after RARP are depicted in Fig. 2. Of 21 patients who remained incontinent after 12 months, anticholinergic agents or functional electrical stimulation with biofeedback were used to treat 18 patients. Anti-incontinence surgeries were performed for three patients with continued urinary incontinence (artificial urinary sphincter in two patients and suburethral tension adjustable sling [REMEEX system] in one patient).

Logistic regression analysis was used to identify prognostic factors for urinary incontinence at six months and 12 months after RARP, and the results are summarized in Table 2. On multivariate analysis, only age (95% confidence interval [CI] 1.01-1.14; p=0.022) was associated with urinary incontinence at six months, while both age (95% CI 1.02-1.23; p=0.017) and DM (95% CI 1.03-12.74; p=0.046) were associated with urinary incontinence at 12 months.

The impact of preoperative and postoperative MUL measured by MRI on urinary incontinence six months and 12 months after RARP is shown in Table 3. On multivariate logistic regression analysis adjusted for age, preoperative MUL [less than or equal to]16 mm (95% CI 1.01-1.14; p=0.022), postoperative MUL [less than or equal to]14 mm (95% CI 1.16-9.80; p=0.025) and percent change of MUL >18% (95% CI 1.17-7.23; p=0.021) were significantly associated with urinary incontinence at six months. When adjusted for age and DM, preoperative MUL [less than or equal to]13.5 mm (95% CI 1.85-19.21; p=0.003) and postoperative MUL [less than or equal to]13 mm (95% CI 1.24-13.84; p=0.021), but not percent change of MUL, were associated with urinary incontinence 12 months after RARP.

Discussion

In the present study, urinary incontinence was identified in 24.7% patients at six months and 11.3% patients at 12 months after RARP. Age was commonly associated with urinary incontinence at six months and 12 months. DM is another important factor that affects urinary continence recovery after RARP. When stratified according to preoperative and postoperative MUL adjusted by the abovementioned prognostic factors, preoperative MUL [less than or equal to]16 mm, postoperative MUL [less than or equal to]14 mm, and percent change of MUL >18% were significantly associated with urinary incontinence at six months. At 12 months, preoperative MUL [less than or equal to]13.5 mm and postoperative MUL [less than or equal to]13 mm had impacts on urinary incontinence, but not percent change of MUL. These results indicated that efforts to preserve MUL are highly recommended during surgery for optimal continence outcomes. To the best of our knowledge, this is the largest study to examine the relationship between both preoperative and postoperative MUL and urinary continence after RARP.
Time after RARP

 1 month   19.4
 3 months  44.1
 6 months  75.3
12 months  88.7

Fig. 2. Serial changes in urinary continence recovery after
robotic-assisted radical prostatectomy.

Note: Table made from bar graph


Recent advances in knowledge of pelvic structure have led to increased understanding of the urinary continence mechanism. (15) In brief, the urethral sphincter system and periurethral support system are two main mechanisms of preserving urinary continence. The external striated sphincter is the main structure maintaining urethral closure pressure greater than bladder pressure. This sphincter is mostly located from the prostate apex to the urethra at the level of the penile bulb. (13) Dubbelman et al reported that maximal urethral closure pressure decreased approximately 27% from 89.6 cm [H.sub.2]O preoperatively to 65.2 cm [H.sub.2]O postoperatively. (17) Therefore, longer MUL values are more likely to maintain sphincter function and detailed manipulation of the prostate apex is recommended to avoid damage to the external striated sphincter.

The development of MRI has enabled more accurate measurement of perioperative MUL. After the first study by Coakley et al, (18) recent studies have showed that preoperative MUL was associated with recovery of continence after radical prostatectomy. (13,16,19-21) Our study not only confirmed their findings, but also evaluated the relationship between postoperative MUL and urinary continence. Our results showed that postoperative MUL was significantly associated with urinary continence recovery, indicating that residual MUL also influenced recovery of continence. When considering that percent change of MUL >18% was significantly associated with urinary incontinence at six months, an effort should be made to preserve maximal MUL to reduce early urinary incontinence during RARP.

In our study, there was a difference in MUL associated with urinary incontinence between six months and 12 months after RARP. These results suggest that the restoration of urinary continence could be enhanced with time. A possible explanation for this is the repair over time of the nerve and periurethral supporting system damaged during RARP. The external striated sphincter is innervated from the pelvic plexus and from the perineal branch and intrapelvic branch of the pudendal nerve.(15) These nerves come into the posterior aspects of the external striated sphincter and are intertwined with the prostatic apex. A median of 12 months is needed to restore function from neuropraxic injury after radical prostatectomy when postulated from the recovery for erectile dysfunction. (22) Van der Poel et al identified that preservation of the lateral prostatic fascia could protect neurovascular structures that are crucial for improving post-prostatectomy continence. (23)

The development of diagnostic imaging modalities, such as ultrasonography or functional MRI, have helped determine the impact of preoperative and postoperative MUL on urinary continence. (24,25) In addition to MUL, they could easily visualize the motility of urethra and pelvic wall, bladder-urethra angle, and scarring or foreign body of anastomosis site. Moreover, healing of anastomosis site is also important, as iatrogenic sphincter lesion could cause early incontinence after radical prostatectomy. Gerullis et al reported that sphincter injury, such as suture penetration, was identified in patients with early incontinence after surgery. (26)

Our study also showed that DM is an important factor that affects urinary continence recovery at 12 months after RARP. In a study by Teber et al, (27) patients with DM require more time to regain urinary continence than non-DM patients. They demonstrated that patients with DM for more than five years were more likely to experience urinary incontinence than those with DM for less than five years at three, 12, and 24 months postoperatively. They suggested that diabetic nephropathy would not only affect autonomic nerves involved in the external striated sphincter, but also impair bladder function.

Collectively, patients of older age and with DM are more likely not to regain urinary continence until 12 months after RARP. Because both preoperative MUL and postoperative MUL are correlated with urinary incontinence, precise manipulation of the prostatic apex is recommended to preserve the urethral sphincter system during RARP. In patients with preoperative MUL [less than or equal to]13.5 mm and postoperative MUL [less than or equal to]13 mm, reconstruction and reinforcement of the periurethral support system should be performed, including anterior and posterior reconstruction or total reconstruction. In a study by Nguyen et al, (19) in patients with short sphincters less than 14 mm, the continence rate was 47% for the control group at six months, while it was 81% for those who underwent anterior reconstruction and 90% for those who underwent total reconstruction. They demonstrated that with reconstruction of the support system, the continence of the short sphincter group did not differ from that of the long sphincter group.

Our study had several important limitations. First, this study had a retrospective design, relatively small size, and was performed by three surgeons, raising the potential for selection bias. However, to our knowledge, this is the largest study to measure both preoperative and postoperative MUL with 3T MRI and evaluate their relationship with urinary continence after RARP. Second, urinary continence status was evaluated based on the number of pads patients used, which is relatively subjective. In general, measurement of the 24-hour pad weight is considered the most accurate test. (28) However, this is not easy to apply in practice, so we measured the severity of urinary incontinence by a self-reported questionnaire that could also reflect self-satisfaction. Finally, because we focused on the impacts of preoperative and postoperative MUL on urinary incontinence, other parameters affecting urinary incontinence might be underestimated.

Conclusion

Preoperative and postoperative MUL measured with 3T MRI were significantly associated with urinary continence recovery after RARP. These findings suggest that efforts to preserve MUL are highly recommended during surgery for optimal continence outcomes. Further large-scale studies are needed to verify our results for clinical application.

Competing interests: The authors report no competing personal or financial interests.

This paper has been peer-reviewed.

References

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(11.) Paparel P, Akin O, Sandhu JS, et al. Recovery of urinary continence after radical prostatectomy: Association with urethral length and urethral fibrosis measured by preoperative and postoperative endorectal magnetic resonance imaging. Eur Urol 2009;55:629-37. https://doi.org/10.1016/j.eururo.2008.08.057

(12.) Shikanov S, Desai V, Razmaria A, et al. Robotic radical prostatectomy for elderly patients: Probability of achieving continence and potency one year after surgery. J Urol 2010;183:1803-7. https://doi.org/10.1016/j.juro.2010.01.016

(13.) Hakimi AA, Faleck DM, Agalliu I, et al. Preoperative and intraoperative measurements of urethral length as predictors of continence after robot-assisted radical prostatectomy. J Endourol 2011;25:1025-30. https://doi.org/10.1089/end.2010.0692

(14.) Hamada A, Razdan S, Etafy MH, et al. Early return of continence in patients undergoing robot-assisted laparoscopic prostatectomy using modified maximal urethral length preservation technique. J Endourol 2014;28:930-8. https://doi.org/10.1089/end.2013.0794

(15.) Kojima Y, Takahashi N, Haga N, et al. Urinary incontinence after robot-assisted radical prostatectomy: Pathophysiology and intraoperative techniques to improve surgical outcome. Int J Urol 2013;20:1052-63. https://doi.org/10.1111/iju.12214

(16.) von Bodman C, Matsushita K, Savage C, et al. Recovery of urinary function after radical prostatectomy: Predictors of urinary function on preoperative prostate magnetic resonance imaging. J Urol 2012;187:945-50. https://doi.org/10.1016/j.juro.2011.10.143

(17.) Dubbelman YD, Groen J, Wildhagen M F, et al. Urodynamic quantification of decrease in sphincter function after radical prostatectomy: Relation to postoperative continence status and the effect of intensive pelvic floor muscle exercises. Neurourol Urodyn 2012;31:646-51. https://doi.org/10.1002/nau.21243

(18.) Coakley FV, Eberhardt S, Kattan M W, et al. Urinary continence after radical retropubic prostatectomy: Relationship with membranous urethral length on preoperative endorectal magnetic resonance imaging. J Urol 2002;168:1032-5. https://doi.org/10.1016/S0022-5347(05)64568-5

(19.) Nguyen L, Jhaveri J, Tewari A. Surgical technique to overcome anatomical shortcoming: Balancing post-prostatectomy continence outcomes of urethral sphincter lengths on preoperative magnetic resonance imaging. J Urol 2008;179:1907-11. https://doi.org/10.1016/j.juro.2008.01.036

(20.) Cameron A P, Suskind AM, Neer C, et al. Functional and anatomical differences between continent and incontinent men post radical prostatectomy on urodynamics and 3T MRI: A pilot study. Neurourol Urodyn 2015;34:527-32. https://doi.org/10.1002/nau.22616

(21.) Haga N, Ogawa S, Yabe M, et al. Association between postoperative pelvic anatomic features on magnetic resonance imaging and lower tract urinary symptoms after radical prostatectomy. Urology 2014;84:642-9. https://doi.org/10.1016/j.urology.2014.04.044

(22.) Song C, Doo CK, Hong JH, et al. Relationship between the integrity of the pelvic floor muscles and early recovery of continence after radical prostatectomy. J Urol 2007;178:208-11. https://doi.org/10.1016/j.juro.2007.03.044

(23.) van der Poel HG, de Blok W, Joshi N, et al. Preservation of lateral prostatic fascia is associated with urine continence after robotic-assisted prostatectomy. Eur Urol 2009;55:892-900. https://doi.org/10.1016/j.eururo.2009.01.021

(24.) Kirschner-Hermanns R, Anding R, Stief CG, et al. [Imaging diagnostics of the male pelvic floor]. Urologe A 2013;52:527-32. https://doi.org/10.1007/s00120-013-3142-4

(25.) Mizutani Y, Uehara H, Fujisue Y, et al. Urinary continence following laparoscopic radical prostatectomy: Association with postoperative membranous urethral length measured using real-time intraoperative transrectal ultrasonography. Oncol Lett 2012;3:181-4.

(26.) Gerullis H, Georgas E, Quast S, et al. Early endoscopic detection and subsequent removal of sphincter penetrating anastomotic sutures may prevent irreversible urinary incontinence after radical prostatectomy. J Endourol 2012;26:889-94. https://doi.org/10.1089/end.2011.0643

(27.) Teber D, Sofikerim M, Ates M, et al. Is type 2 diabetes mellitus a predictive factor for incontinence after laparoscopic radical prostatectomy? A matched pair and multivariate analysis. J Urol 2010;183:1087-91. https://doi.org/10.1016/j.juro.2009.11.033

(28.) Bauer RM, Gozzi C, Hubner W, et al. Contemporary management of post-prostatectomy incontinence. Eur Urol 2011;59:985-96. https://doi.org/10.1016/j.eururo.2011.03.020

Wan Song, MD; (1) Chan Kyo Kim, MD; (2) Byung Kwan Park, MD; (2) Hwang Gyun Jeon, MD; (1) Byong Chang Jeong, MD; (1) Seong Il Seo, MD; (1) Seong Soo Jeon, MD; (1) Han Yong Choi, MD; (1) Hyun Moo Lee, MD (1)

(1) Department of Urology, Samsung Medical Centre, Sungkyunkwan University School of Medicine, Seoul, Korea; (2) Department of Radiology and Centre for Imaging Science, Samsung Medical Centre, Sungkyunkwan University School of Medicine, Seoul, Korea

Published online March 16, 2017

Correspondence: Dr. Hyun Moo Lee, Department of Urology, Samsung Medical Centre, Sungkyunkwan University School of Medicine, Seoul, Korea; besthml@medimail.co.kr

Caption: Fig. 1. Preoperative membranous urethral length measured in the (A) sagittal and (B) coronal planes, and postoperative membranous urethral length measured in the (C) sagittal and (D) coronal planes from T2-weighted magnetic resonance imaging.
Table 1. Baseline characteristics   of 186 patients (mean [+ or -]
SD [median, range] or n [%])

                                 Total
Variables

No. of patients                   186
Age at surgery, years              64.5 [+ or -] 7.6 (65.0, 38.0-79.0)
Preoperative PSA, ng/ml             8.25 [+ or -] 9.11
                                   (6.30, 1.35-83.50)
Diabetes mellitus                  31 (16.7)
Hypertension                       72 (38.7)
BMI, kg/[m.sup.2]                  24.5 [+ or -] 2.9 (24.2, 16.0-35.1)
Prostate volume, radiologic, ml    34.0 [+ or -] 15.9 (30.0, 8.0-113.0)
ASA score
 1                                 49 (26.3)
 2-3                              137 (73.7)
Operative findings
 Nerve preservation
  None or unilateral               82 (44.1)
  Bilateral                       104 (55.9)
 Operation time, min              294.5 [+ or -] 88.9
                                 (298.0, 96.0-600.0)
 EBL, ml                          304.9 [+ or -] 217.5
                                 (250.0, 30.0-1800.0)
Pathological findings
 Gleason score
  [less than or equal to]6         33 (17.7)
  7                               137 (73.7)
  [greater than or equal to]8      16 (8.6)
Extracapsular extension
  Yes                              41 (22.0)
  No                              145 (78.0)
Seminal vesicle invasion
  Yes                               7 (3.8)
  No                              179 (96.2)
Positive surgical margin
  Yes                              21 (11.3)
  No                              165 (88.7)
Membranous urethral length, mm
  Preoperative MRI                 15.6 [+ or -] 2.7 (15.9, 7.2-22.9)
  Postoperative MRI                14.7 [+ or -] 2.7 (14.9, 6.3-22.8)

                                 At 12 months after RARP
Variables                        Continence (+)

No. of patients                   165
Age at surgery, years              64.0 [+ or -] 7.7 (65.0, 38.0-78.0)
Preoperative PSA, ng/ml             8.18 [+ or -] 9.25
                                   (6.07, 1.35-83.50)
Diabetes mellitus                  24 (14.5)
Hypertension                       60 (36.4)
BMI, kg/[m.sup.2]                  24.4 [+ or -] 2.9 (24.2, 16.0-35.1)
Prostate volume, radiologic, ml    33.8 [+ or -] 15.7 (30.0, 8.0-113.0)
ASA score
 1                                 47 (28.5)
 2-3                              118 (71.5)
Operative findings
 Nerve preservation
  None or unilateral               72 (43.6)
  Bilateral                        93 (56.4)
 Operation time, min              292.2 [+ or -] 86.9
                                 (298.0, 96.0-600.0)
 EBL, ml                          299.8 [+ or -] 214.5
                                 (250.0, 30.0-1800.0)
Pathological findings
 Gleason score
  [less than or equal to]6         33 (20.0)
  7                               119 (72.1)
  [greater than or equal to]8      13 (7.9)
Extracapsular extension
  Yes                              31 (18.8)
  No                              134 (81.2)
Seminal vesicle invasion
  Yes                               5 (3.0)
  No                              160 (97.0)
Positive surgical margin
  Yes                              17 (10.3)
  No                              148 (89.7)
Membranous urethral length, mm
  Preoperative MRI                 15.9 [+ or -] 2.6 (16.1, 10.2-22.9)
  Postoperative MRI                14.9 [+ or -] 2.5 (15.1, 8.8-22.8)

                                 Continence (-)
Variables

No. of patients                    21
Age at surgery, years              68.5 [+ or -] 6.0 (69.0, 56.0-79.0)
Preoperative PSA, ng/ml             8.77 [+ or -] 8.12
                                   (6.50, 2.36-38.60)
Diabetes mellitus                   7 (33.3)
Hypertension                       12 (57.1)
BMI, kg/[m.sup.2]                  25.3 [+ or -] 2.3 (25.4, 21.8-30.0)
Prostate volume, radiologic, ml    35.3 [+ or -] 17.4 (28.0, 15.0-72.0)
ASA score
 1                                  2 ( 9.5)
 2-3                               19 (90.5)
Operative findings
 Nerve preservation
  None or unilateral               10 (47.6)
  Bilateral                        11 (52.4)
 Operation time, min              312.6 [+ or -] 104.6
                                 (290.0, 120.0-515.0)
 EBL, ml                          344.8 [+ or -] 241.6
                                 (300.0, 100.0-1000.0)
Pathological findings
 Gleason score
  [less than or equal to]6          3 (14.3)
  7                                15 (71.4)
  [greater than or equal to]8       3 (14.3)
Extracapsular extension
  Yes                               5 (23.8)
  No                               16 (76.2)
Seminal vesicle invasion
  Yes                               2 (9.5)
  No                               19 (90.5)
Positive surgical margin
  Yes                               4 (19.0)
  No                               17 (81.0)
Membranous urethral length, mm
  Preoperative MRI                 13.9 [+ or -] 2.9 (13.5, 7.2-19.0)
  Postoperative MRI                13.0 [+ or -] 3.3 (13.8, 6.3-18.0)

                                 P
Variables

No. of patients
Age at surgery, years            0.013
Preoperative PSA, ng/ml          0.583

Diabetes mellitus                0.055 (*)
Hypertension                     0.066
BMI, kg/[m.sup.2]                0.148
Prostate volume, radiologic, ml  0.991
ASA score                        0.070 (*)
 1

 2-3
Operative findings
 Nerve preservation              0.729
  None or unilateral
  Bilateral
 Operation time, min             0.507

 EBL, ml                         0.514

Pathological findings
 Gleason score
  [less than or equal to]6
  7
  [greater than or equal to]8
Extracapsular extension          0.583
  Yes
  No
Seminal vesicle invasion         0.180 (*)
  Yes
  No
Positive surgical margin         0.266 (*)
  Yes
  No
Membranous urethral length, mm
  Preoperative MRI               0.004
  Postoperative MRI              0.015

(*) Fisher's exact test. ASA: American Society of Anesthesiologists;
BMI: body mass index; EBL: estimated blood loss; MRI: magnetic
resonance imaging; PSA: prostate-specific antigen; RARP:
robotic-assisted radical prostatectomy; SD: standard deviation.

Table 2. Logistic regression analyses for identifying predictive
factors for urinary incontinence...

(A) 6 months after RARP
Variables                                            Univariate
                                                OR    95% CI      p

Age (*)                                         1.07  1.02-1.12   0.007
Preoperative PSA (*)                            1.01  0.98-1.05   0.443
Diabetes mellitus (vs. no)                      1.89  0.83-4.31   0.133
Hypertension (vs. no)                           1.65  0.84-3.24   0.145
BMI (*)                                         1.03  0.92-1.16   0.604
Prostate volume (*)                             1.01  0.99-1.03   0.361
ASA score (2-3 vs. 1)                           2.39  0.99-5.77   0.053
Nerve-sparing                                   0.82  0.42-1.60   0.556
(Bilateral versus none or unilateral)
Operation time (*)                              1.00  0.99-1.00   0.976
EBL (*)                                         1.00  0.99-1.00   0.604
Pathological Gleason score
[less than or equal to]6                        1.00  ref
7                                               2.07  0.74-5.77   0.163
[greater than or equal to]8                     1.87  0.43-8.19   0.408
Pathological stage ([greater than or equal to]  1.83  0.86-3.90   0.117
T3 vs. [less than or equal to]T2)
(B) 12 months after RARP
Age (*)                                         1.10  1.02-1.18   0.013
Preoperative PSA (*)                            1.01  0.96-1.05   0.782
Diabetes mellitus (vs. no)                      2.94  1.08-8.03   0.036
Hypertension (vs. no)                           2.33  0.93-5.86   0.071
BMI (*)                                         1.10  0.94-1.28   0.224
Prostate volume (*)                             1.01  0.98-1.03   0.674
ASA score (2-3 vs. 1)                           3.78  0.85-16.89  0.081
Nerve-sparing                                   0.85  0.34-2.12   0.729
(Bilateral vs. none or unilateral)
Operation time (*)                              1.01  1.00-1.01   0.324
EBL(*)                                          1.00  0.99-1.00   0.378
Pathological Gleason score
[less than or equal to]6                        1.00  ref
7                                               2.07  0.74-5.77   0.163
[greater than or equal to]8                     1.87  0.43-8.19   0.408
Pathological stage ([greater than or equal to]  1.70  0.84-3.42   0.139
T3 vs. [less than or equal to]T2)

(A) 6 months after RARP
Variables                                          Multivariate
                                                OR    95% CI      p

Age (*)                                         1.07  1.01-1.14   0.022
Preoperative PSA (*)                            1.01  0.97-1.04   0.784
Diabetes mellitus (vs. no)                      1.92  0.79-4.66   0.152
Hypertension (vs. no)                           1.08  0.49-2.39   0.849
BMI (*)                                         1.04  0.91-1.19   0.584
Prostate volume (*)                             1.01  0.98-1.03   0.660
ASA score (2-3 vs. 1)                           1.98  0.69-5.68   0.206
Nerve-sparing                                   1.19  0.53-2.71   0.672
(Bilateral versus none or unilateral)
Operation time (*)                              1.00  0.99-1.00   0.832
EBL (*)                                         1.00  0.99-1.00   0.920
Pathological Gleason score
[less than or equal to]6                        1.00   ref
7                                               1.31  0.42-4.11   0.644
[greater than or equal to]8                     0.94  0.17-5.28   0.944
Pathological stage ([greater than or equal to]  1.78  0.77-4.09   0.178
T3 vs. [less than or equal to]T2)
(B) 12 months after RARP
Age (*)                                         1.12  1.02-1.23   0.017
Preoperative PSA (*)                            0.99  0.93-1.07   0.884
Diabetes mellitus (vs. no)                      3.61  1.03-12.74  0.046
Hypertension (vs. no)                           1.42  0.46-4.40   0.546
BMI (*)                                         1.17  0.96-1.43   0.116
Prostate volume (*)                             1.00  0.97-1.03   0.930
ASA score (2-3 vs. 1)                           2.32  0.39-13.83  0.357
Nerve-sparing                                   2.04  0.59-7.02   0.260
(Bilateral vs. none or unilateral)
Operation time (*)                              1.00  0.99-1.00   0.777
EBL(*)                                          1.00  0.99-1.00   0.908
Pathological Gleason score
[less than or equal to]6                        1.00   ref
7                                               1.31  0.42-4.11   0.644
[greater than or equal to]8                     0.94  0.17-5.28   0.944
Pathological stage ([greater than or equal to]  1.39  0.62-3.11   0.421
T3 vs. [less than or equal to]T2)

(*) Continuous variables. ASA: American Society of Anesthesiologists;
BMI: body mass index; CI: confidential interval; EBL: estimated blood
loss; OR: odds ratio; PSA: prostate-specific antigen; RARP:
robotic-assisted radical prostatectomy.

Table 3. Association of preoperative and postoperative MRI-measured
membranous urethral length with urinary incontinence...

(A) 6 months after RARP
                                                      Univariate
                                                OR    95% CI       p

Preoperative membranous urethral length,        3.19  1.55-6.58    0.002
mm [less than or equal to]16 vs. >16
Preoperative membranous urethral length, mm
 Membranous urethral length >16                 1.00  ref
 13.5<Membranous urethral length                2.60  1.13-5.95
[less than or equal to]16                                          0.024
 Membranous urethral length                     4.08  1.74-9.56
[less than or equal to]13.5                                        0.001
Postoperative membranous urethral length,       3.89  1.83-8.27   <0.001
mm [less than or equal to]15 vs. >15
Postoperative membranous urethral length, mm
 Membranous urethral length >15                 1.00  ref
 14< Membranous urethral length                 1.91  0.63-5.75
[less than or equal to]15                                         0.250
 13< Membranous urethral length                 3.94  1.40-11.06
[less than or equal to]14                                         0.009
 Membranous urethral length                     5.60  2.36-13.27
[less than or equal to]13                                         <0.001
Percent change of membranous urethral length,   1.65  0.84-3.25   0.150
% >6 vs. [less than or equal to]6
Percent change of membranous urethral length,
% Percent change [less than or equal to]6       1.00   ref
 6< Percent change [less than or equal to]12    0.89  0.32-2.48   0.822
 12<Percent change [less than or equal to]18    1.50  0.60-3.78   0.390
 Percent change >18                             3.06  1.26-7.43   0.014


(A) 6 months after RARP
                                                      Age adjusted
                                               OR    95% CI       p

Preoperative membranous urethral length,       3.20  1.54-6.68    0.002
mm [less than or equal to]16 vs. >16
Preoperative membranous urethral length, mm
 Membranous urethral length >16                1.00  ref
 13.5<Membranous urethral length               2.71  1.16-6.32    0.021
[less than or equal to]16
 Membranous urethral length                    3.88  1.63-9.24    0.002
[less than or equal to]13.5
Postoperative membranous urethral length,      3.75  1.75-8.07    0.001
mm [less than or equal to]15 vs. >15
Postoperative membranous urethral length, mm
 Membranous urethral length >15                1.00  ref
 14< Membranous urethral length                1.81  0.59-5.54    0.299
[less than or equal to]15
 13< Membranous urethral length                3.37  1.16-9.80    0.025
[less than or equal to]14
 Membranous urethral length                    5.84  2.41-14.12  <0.001
[less than or equal to]13
Percent change of membranous urethral length,  1.63  0.82-3.26    0.167
% >6 vs. [less than or equal to]6
Percent change of membranous urethral length,
% Percent change [less than or equal to]6      1.00  ref
 6< Percent change [less than or equal to]12   0.81  0.28-2.29    0.685
 12<Percent change [less than or equal to]18   1.68  0.65-4.36    0.283
 Percent change >18                            2.94  1.17-7.23    0.021

(B) 12 months after RARP
                                                     Univariate
                                               OR    95% CI      p

Preoperative membranous urethral length,       2.66  0.98-7.18   0.054
mm [less than or equal to]16 vs. >16
Preoperative membranous urethral length, mm
 Membranous urethral length >16                1.00  ref
 13.5<Membranous urethral length               1.16  0.31-4.30   0.828
[less than or equal to]16
 Membranous urethral length                    5.03  1.71-14.75  0.003
[less than or equal to]13.5
Postoperative membranous urethral length,      3.24  1.13-9.25   0.028
mm [less than or equal to]15 vs. >15
Postoperative membranous urethral length, mm
 Membranous urethral length >15                1.00  ref
 14< Membranous urethral length                2.26  0.50-10.21  0.288
[less than or equal to]15
 13< Membranous urethral length                2.77  0.69-11.12  0.152
[less than or equal to]14
 Membranous urethral length                    4.15  1.30-13.25  0.016
[less than or equal to]13
Percent change of membranous urethral length,  1.04  0.42-2.57   0.940
% >6 vs. [less than or equal to]6
Percent change of membranous urethral length,
% Percent change [less than or equal to]6      1.00  ref
 6< Percent change [less than or equal to]12   0.80  0.21-3.11   0.747
 12<Percent change [less than or equal to]18   0.80  0.21-3.11   0.747
 Percent change >18                            1.60  0.50-5.12   0.429

(B) 12 months after RARP
                                                     Multivariate (#)
                                               OR    95% CI      p

Preoperative membranous urethral length,       2.72  0.97-7.64   0.057
mm [less than or equal to]16 vs. >16
Preoperative membranous urethral length, mm
 Membranous urethral length >16                1.00  ref
 13.5<Membranous urethral length               1.10  0.28-4.28   0.895
[less than or equal to]16
 Membranous urethral length                    5.95  1.85-19.21  0.003
[less than or equal to]13.5
Postoperative membranous urethral length,      3.10  1.05-9.18   0.041
mm [less than or equal to]15 vs. >15
Postoperative membranous urethral length, mm
 Membranous urethral length >15                1.00  ref
 14< Membranous urethral length                1.96  0.40-9.58   0.408
[less than or equal to]15
 13< Membranous urethral length                2.63  0.63-10.99  0.185
[less than or equal to]14
 Membranous urethral length                    4.15  1.24-13.84  0.021
[less than or equal to]13
Percent change of membranous urethral length,  0.84  0.32-2.19   0.716
% >6 vs. [less than or equal to]6
Percent change of membranous urethral length,
% Percent change [less than or equal to]6      1.00  ref
 6< Percent change [less than or equal to]12   0.56  0.14-2.34   0.428
 12<Percent change [less than or equal to]18   0.70  0.17-2.92   0.623
 Percent change >18                            1.35  0.40-4.60   0.629

(#) Adjusted for age and diabetes mellitus. CI: confidence interval;
MRI: magnetic resonance imaging; OR: odds ratio; RARP: robotic-assisted
radical prostatectomy.
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Title Annotation:ORIGINAL RESEARCH
Author:Song, Wan; Kim, Chan Kyo; Park, Kwan Byung; Jeon, Hwang Gyun; Jeong, Byong Chang; Seong II, Seo; Jeo
Publication:Canadian Urological Association Journal (CUAJ)
Article Type:Report
Date:Mar 1, 2017
Words:6187
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