# Association Between Postoperative Pancreatitis and Clinically Relevant Postoperative Pancreatic Fistula After Pancreaticoduodenectomy: A Prospective Observational Study From a Single Tertiary Care Center

## TL;DR

This study shows that measuring amylase levels in blood and drainage fluid on the first day after surgery can help predict a serious complication following pancreatic surgery.

## Contribution

The study identifies early postoperative amylase thresholds that reliably predict clinically relevant pancreatic fistulas.

## Key findings

- Postoperative day 1 drain fluid amylase above 3,011 IU/L has high specificity for predicting clinically relevant pancreatic fistulas.
- A serum amylase level of ≤363 IU/L on postoperative day 1 effectively excludes clinically relevant pancreatic fistulas.
- A dilated pancreatic duct (>3 mm) is inversely associated with clinically relevant pancreatic fistulas.

## Abstract

Backgrounds/Aims: Postoperative pancreatic fistula remains a key determinant of morbidity following pancreaticoduodenectomy (PD). This study assessed whether postoperative day 1 (POD 1) serum amylase (SA) and drain fluid amylase (DFA) can predict clinically relevant postoperative pancreatic fistula (CR-POPF) to facilitate early risk-stratified postoperative management.

Methods: This prospective observational cohort study (January 2021-April 2023) included adult patients undergoing PD with duct-to-mucosa pancreaticojejunal anastomosis. SA and DFA levels were measured on POD 1, POD3, and POD 5. The primary outcome was CR-POPF, defined according to the 2016 International Study Group of Pancreatic Surgery criteria. Receiver operating characteristic (ROC) analyses were performed to identify optimal POD 1 cutoff values.

Results: Among 57 patients, nine (15.8%) developed CR-POPF. Mean POD 1 SA and DFA levels were significantly higher in patients who developed CR-POPF compared with those who did not (SA: 464 ± 164 vs 262 ± 176 IU/L, p = 0.002; DFA: 12,664 ± 8,800 vs 1,045 ± 1,128 IU/L, p < 0.001). POD 1 SA demonstrated an AUC of 0.803 (95% CI 0.677-0.897), with an optimal cutoff of 363 IU/L (sensitivity 77.78%, specificity 75.0%, negative predictive value (NPV) 94.7%). POD 1 DFA showed superior discrimination with an AUC of 0.889 (95% CI 0.778-0.957); a cutoff of 3,011 IU/L yielded a sensitivity of 66.67%, specificity of 97.92%, positive predictive value (PPV) of 85.7%, and NPV of 94.0%. A dilated pancreatic duct (>3 mm) was inversely associated with CR-POPF (p < 0.001).

Conclusions: POD 1 SA and DFA levels provide a reliable early prediction of CR-POPF following PD. A DFA threshold above 3,011 IU/L demonstrates high specificity for CR-POPF, whereas a SA level ≤363 IU/L effectively excludes its occurrence. Incorporation of these parameters into postoperative protocols may aid early drain management decisions and targeted intervention in high-risk patients.