Perirenal Fat Surface Area as a Risk Factor for Morbidity After Elective Colorectal Surgery

BACKGROUND: Visceral obesity appears to be an emerging parameter affecting postoperative outcome after abdominal surgery. However, total visceral fat remains time consuming to calculate, and there is still a lack of data about its value as an independent risk factor in colorectal surgery. OBJECTIVES: The aim of this study was to validate the simple measurement of perirenal fat surface as a surrogate of visceral obesity, and to test the value of perirenal fat surface as a risk factor for morbidity in colorectal surgery and to compare it with the predictive value of other obesity parameters such as BMI and waist-hip ratio. DESIGN: This is a prospective observational cohort study. SETTING: The study was conducted at a tertiary university hospital. PATIENTS: Two hundred twenty-four consecutive patients (130 male) undergoing elective colorectal surgery with a mean age of 65.2 years (SD, 12.9) were identified. INTERVENTION: Elective colorectal resections were performed. MAIN OUTCOME MEASURES: We assessed complications as the primary outcome measure. Secondary outcome measures were the conversion rates, duration of operation, and length of hospital stay. RESULTS: Perirenal fat surface was validated as a surrogate of visceral fat and a strong correlation between the 2 was confirmed (Spearman correlation coefficient = 0.96). The overall postoperative complication rate was 22.8% (51/224) with 14.7% moderate complications (grade I and II) and 7.6% severe complications (grade III-IV), with a mortality rate of 0.5%. Multivariate analysis confirmed perirenal fat surface as an independent risk factor for postoperative complications (OR, 3.87; 95% CI, 1.73-8.64; p = 0.001), whereas BMI and waist-hip ratio were not statistically associated with postoperative complications (OR, 1.16; 95% CI, 0.51-2.66; p = 0.72). LIMITATIONS: This study was limited by its sample size. CONCLUSION: Perirenal fat surface is an excellent and easy-to-reproduce indicator of visceral fat volume. Furthermore, perirenal fat surface is an independent risk factor for postoperative outcome in colorectal surgery that appears to be of higher predictive value than BMI and waist-hip ratio.