The Change of Urea to Creatinine Ratio is Associated With Postoperative Complications and Skeletal Muscle Wasting in Pancreatic Cancer Patients Underwent Pancreatoduodenectomy

Background: Surgical Patients with depleted skeletal muscle mass tend to have a worse outcome in the perioperative period, but the muscle mass is difficult to quantify. Here, we aimed to evaluate the relationship of perioperative change of serum urea to creatinine ratio (CUCR) with postoperative complication and skeletal muscle mass in pancreatic cancer patients underwent pancreatoduodenectomy (PD). Methods: Pancreatic cancer patients underwent PD were included retrospectively. We analyzed the association of serum urea, creatinine, and urea to creatinine ratio (UCR) between patients with and without major postoperative complications. In a subset of patients with serial CT scans, we tested the correlation of the CUCR and the changes of CT-derived skeletal muscle area (SMA). Furthermore, the capacity of complication prediction of CUCR and CT-derived parameter were compared in these patients. Results: We included 321 surgical patients from January 2014 to July 2020. Patients were grouped with high- and low CUCR according ROC curve (cut-off: 71.3 for male and 67.4 for female). Patients with high CUCR (n=175) have higher complication rate (30.3% vs. 21.1%, p=0.002), including POPF (23.4% vs. 15.1%, p=0.017), infection rate (16.0% vs. 11.0%, p=0.043) and longer postoperative days to discharge (16.7±6.5, vs. 12.1±4.2, p=0.031). Multivariable logistic regression demonstrated CUCR was an independent predictor for complications in these patients, independent of age, sex and BMI. In a subset patients with serial CT scans, spearman correlation analysis shown both L3 muscle area and L4-psoas area were significantly correlated with CUCR (R 2 = 0.64, p < 0.05; R 2 = 0.62, p < 0.05, respectively). Conclusion: Perioperative CUCR is an independent predictor for postoperative complications in pancreatic cancer patients underwent PD procedure. Elevated CUCR is a reflection of skeletal muscle wasting in postoperative surgical patients.