MP52-15: Abdominal subcutaneous fat thickening is the useful marker to predict lower urinary tract dysfunction after robot-assisted radical prostatectomy

Shunta Makabe*, Yusuke Kirihana, Tomoyuki Kumekawa, Hiroki Natsuya, Yusuke Hakozaki, Shunsuke Yoshioka, Yu Endo, Akihisa Hasegawa, Yuki Harigane, Kei Yaginuma, Hitomi Imai, Akifumi Onagi, Kanako Matsuoka, Tomoyuki Koguchi, Junya Hata, Yuichi Sato, Hidenori Akaihata, Masao Kataoka, Yoshiyuki Kojima, Fukushima, Japan

Introduction: Obesity is known as an important patient factor to determine lower urinary tract dysfunction (LUTD) after robot-assisted radical prostatectomy (RARP). BMI is one of the makers of obesity, and usually used to evaluate the effect of obesity on lower urinary tract function. However, BMI does not differentiate between fat and nonfat tissue including muscle. We considered the possibility that total body or local fat might more accurately reflect obesity compared to BMI. This study aimed to investigate whether total body or local fat was useful predictors of LUTD associated with obesity after RARP.

Methods: A total of 536 patients (66.9±5.3 years) who underwent RARP at our institution were included in this study. We measured the thickness of abdominal subcutaneous fat (SCFT) and preprostatic fat (PPFT) in preoperative magnetic resonance imaging as evaluation items for total body and local fat. Uroflowmetry (UFM), post-void residual urine volume (PVR) and one-hour pad test were performed in all patients at 1,3,6 and 12 months after RARP. Bladder voiding efficiency (BVE, defined as the ratio between voided volume and total bladder capacity by UFM and PVR) and volume of incontinence at each month after RARP were used as postoperative objective parameters reflecting lower urinary tract function. The association between preoperative total body and local fat and the postoperative objective parameters were evaluated.

Results: BVE were significantly correlated with SCFT at 1,3,6 and 12 months after RARP  (p < 0.05). Volume of incontinence were significantly correlated with SCFT at 3,6 and 12 months after RARP (p < 0.05). PPFT did not show a significant correlation with all postoperative objective parameters. In multivariate analysis, SCFT was significantly associated with BVE at 1,3,6 and 12 months after RARP (p < 0.05) and volume of incontinence at 3,6 and 12 months (p < 0.05).

Conclusions: In our study, preoperative SCFT was associated with decreased BVE and increased urinary incontinence, although preoperative PPFT was not associated with LUTD after RARP. These results indicated that total body fat may have a greater effect on the onset of LUTD after RARP than local fat. SCFT might reflect metabolic disorders which were known to be associated with LUTD. Preoperative SCFT measurement may be useful predictor of the onset of LUTD after RARP.

Source of Funding: nothing