Supplementary Material for: Serum creatinine and amylase in drain to predict pancreatic fistula risk after pancreatoduodenectomy

Introduction: The identification of patients with low risk of clinically relevant postoperative pancreatic fistula (CR-POPF) and postoperative hemorrhage (PPH) can guide drain removal after pancreatoduodenectomy (PD). However, drain fluid amylase (DFA) ≤ 5000 U/L on postoperative day (POD) 1 does not robustly predict the absence of CR-POPF. Methods: Consecutive patients undergoing PD at Sun Yat-sen University Cancer Center between July 2018 and October 2021 were analyzed. Recursive partitioning analysis was used to classify patients into groups with different risks of CR-POPF and PPH. Results: Among 288 consecutive patients included, 99 patients (34.38%) developed CR-POPF. Patients with CR-POPF had increased levels of preoperative creatinine (CRE) and POD1 CRE. The combination of POD1 CRE (>104 μmol/L or not) and POD1 DFA (>5000 U/L or not) stratified patients into subgroups with the maximum difference in CR-POPF risk. The CR-POPF rates were 17.82% (36/202) in group A (POD1 CRE ≤ 104 μmol/L and POD1 DFA ≤ 5000 U/L), 53.33% (8/15) in group B (POD1 CRE > 104 μmol/L, and POD1 DFA ≤ 5000 U/L), and 77.46% (55/71) in group C (POD1 DFA > 5000 U/L). The PPH rates were 1.98% (4/202), 20.00% (3/15), and 19.72% (14/71) in groups A, B, and C, respectively. Conclusion: Patients with POD1 DFA ≤ 5000 U/L and POD1 CRE >104 μmol/L have a high risk of CR-POPF and may not benefit from early drain removal. Patients with POD1 DFA ≤ 5000 U/L and POD1 CRE ≤104 μmol/L have low risk of CR-POPF and PPH.