Total Amylase Value in Drains After Gastrectomy for Predicting Postoperative Pancreatic Fistula

Objective: Postoperative pancreatic fistula (POPF) is defined using the ratio of the bilirubin concentration in abdominal drainage fluid to the upper normal range of serum amylase level. However, we hypothesized that the total amylase value in discharge (AVD) on POD 3 may be more sensitive for predicting grade II or higher severe POPF sPOPF, and compared the predictive power of the conventional definition of POPF and AVD for sPOPF. Methods: One hundred and fifty-one patients who underwent gastrectomy between October 2011 and February 2013 were analyzed. A drainage tube was placed in all the cases through the stump of the right gastroepiploic vein and the front of the pancreas to the back of the anastomotic site. The drainage volume and amylase concentration in the discharge were examined on POD 1, 3, and 5. AVD was calculated by multiplying the volume by the amylase concentration. Results: Eight patients (5.3%) developed sPOPF. In univariate analysis, both AVD and the amylase concentration ratio was significantly correlated with sPOPF (P = 0.002 and 0.007, respectively). AVD on POD 3 showed the best predictive performance compared with the amylase concentration ratio on POD 3 (area under the curve 0.876 vs. 0.844). Based on the cutoff values calculated from the ROC curves, AVD was more specific than amylase concentration ratio in predicting sPOPF (specificity: 97.6% vs. 86.0%; PPV: 62.5% vs. 23.1%). Conclusion: AVD on POD 3 is a more specific parameter than conventional amylase concentration ratio in predicting sPOPF.