AUA 2018: Relationship Between Excess Visceral Fat Volume and Overactive Bladder

San Francisco, CA (UroToday.com) Increased body mass index (BMI) status has been reported to be positively associated with an increased risk of urinary incontinence, including both stress urinary incontinence (SUI) and urgency urinary incontinence (UUI). The literature regarding high BMI and SUI is robust and is possibly a result of increased intravesical pressure demands on the continence mechanism due to obesity (Swenson, 2017). However, the mechanism behind high BMI and UUI is still unclear. 

Prior reports have suggested that increased abdominal visceral fat leads to excessive production of various inflammatory cytokines, inducing chronic systemic inflammation and metabolic syndrome (MetS). MetS has been associated with urinary symptoms, including OAB and other lower urinary tract symptoms (LUTS), but no study has elucidated the association between excessive visceral fat and OAB.

Tomohiro Matsuo and his team from Nagasaki University Hospital presented research regarding the relationship between visceral fat volume and OAB morbidity and severity. His group evaluated patients who underwent computed tomography (CT) during a health checkup and had not undergone treatments for lower urinary tract. Subjects completed the OAB symptom score (OABSS), and OAB was defined as a score of ≥2 for urinary urgency and a total score of ≥3. 

Visceral fat measurements were performed using the three-dimensional image analysis system SYNAPSE VINCENT (Fujifilm, Tokyo, Japan). Based on CT measurements, visceral fat area (VFA), visceral fat volume (VFV), subcutaneous fat area (SFA), subcutaneous fat volume (SFV), and total abdominal fat volume (TAV) were calculated (see figure). These measurements were then compared to OAB symptoms and total OABSS. 

Figure. 3D Image Analysis System  SYNAPSE VINCENT
 3D Image Analysis System SYNAPSE VINCEN

190 participants were enrolled in the study, of whom 90 (47.4%) met criteria for having OAB. The mean age was 60.4±14.8 years. BMI in the study population was normal (22.6±0.1) and comparable between OAB and non-OAB groups. On abdominal CT, the non-OAB and OAB groups showed statistically significant differences in VFA (73.8±5.8 vs 112.1±71.3 cm2, P<0.001), VFA/SFA (0.53±0.1 vs 1.07±0.07, P<0.001), VFV (1860.8±1234.5 vs 3167.3±2269.9 cm3, P<0.001), VFV/SFV (0.52±0.28 vs 1.55±3.81, P=0.008), and VFV/TAV (32.5±10.6 vs 49.7±14.3, P<0.001). VFV/TAV had the strongest correlation to the total OABSS score (r=0.464, P<0.001). On multivariate analysis, after accounting for known risk factors of OAB such as age, sex, and high blood pressure, high VFV/TAV value (>0.591) was an independent risk factor of OAB (odds ratio, 4.66; 95% confidence interval, 1.03–33.2, P=0.045).

The study results suggest that excess abdominal visceral fat volume is an important independent risk factor of OAB. Of note, the study population had BMIs that were in the normal range, suggesting that visceral fat volume is a separate risk factor that can increase OAB.

References:
1. Swenson CW, Kolenic GE, Trowbridge ER, Berger MB, Lewicky-Gaupp C, Margulies RU, et al. Obesity and stress urinary incontinence in women: compromised continence mechanism or excess bladder pressure during cough? Int. Urogynecol. J. [Internet]. International Urogynecology Journal; 2017


Presented by: Tomohiro Matsuo, MD, Nagasaki University Hospital, Nagasaki, Japan
Co-Authors: Kyohei Araki, Yuichiro Nakamura, Yuji Sagara, Kojiro Ohba, Yasuyoshi Miyata, Hideki Sakai, Nagasaki, Japan

Written by:  Judy Choi, MD, Assistant Professor, Department of Urology, University of California, Irvine @judymchoi at the 2018 AUA Annual Meeting - May 18 - 21, 2018 – San Francisco, CA USA
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