Drain fluid and serum amylase concentration ratio is the most reliable indicator for predicting postoperative pancreatic fistula after distal pancreatectomy

BACKGROUND: Postoperative pancreatic fistula (POPF) is a major complication of pancreatic surgery. Drain fluid amylase concentration (DAC) is considered a predictive indicator of POPF. However, other indicators related to postoperative drain fluid amylase status exist, and the most reliable indicator for predicting POPF remains unclear. The object of this study is to identify the single most accurate indicator related to drain fluid amylase status of POPF after distal pancreatectomy (DP). METHODS: This single-institution retrospective study included 122 patients who underwent DP. The study was conducted between 2010 and 2022 at Gifu University Hospital. We statistically analyzed DAC, drain fluid amylase amount (DAA) calculated by multiplying DAC and daily drainage volume, and drain and serum amylase concentration ratio (DSACR) to assess the correlation with POPF. RESULTS: Based on the definition and grading of the International Study Group of Pancreatic Fistula, 24.6 (%) of the 122 patients had Grades B and C POPF. The result of the receiver operating characteristic (ROC) curve for predicting POPF after DP, DSACR had the highest area under curve(AUC) value among DAC, DAA, and DSACR both POD1 and POD3. The cutoff value of DSACR on POD1 was 17 (AUC 0.69, sensitivity 80.0%, specificity 58.2%, and accuracy 63.6%). The cutoff value of DSACR on POD3 was 22 (AUC 0.77, sensitivity 77.7%, specificity 73.3%, and accuracy 73.6%). Overall, DSACR on POD3 had the highest AUC value. Furthermore, a multivariate logistic regression analysis revealed that pancreatic texture (soft; odds ratio [OR] 9.22; 95% confidence interval [CI] 2.22–44.19; p < 0.01) and DSACR on POD3 (> 22; OR 8.76; 95% CI 2.78–31.59; p < 0.001) were independently associated with POPF after DP. CONCLUSIONS: DSACR is the most reliable indicator of drain fluid amylase status for predicting POPF after DP.