Nationwide validation of the ISGPS risk classification for postoperative pancreatic fistula after pancreatoduodenectomy: “Less is more”

Background: The International Study Group of Pancreatic Surgery 4-tier (ie, A–D) risk classification for postoperative pancreatic fistula grade B/C is based on pancreatic texture and pancreatic duct size: A (not-soft texture and pancreatic duct >3 mm), B (not-soft texture and pancreatic duct ≤3 mm), C (soft texture and pancreatic duct >3 mm), and D (soft texture and pancreatic duct ≤3 mm). This study aimed to validate the International Study Group of Pancreatic Surgery risk classification for postoperative pancreatic fistula after pancreatoduodenectomy. Methods: Consecutive patients after pancreatoduodenectomy for all indications (2014–2021) were included from the nationwide, mandatory Dutch Pancreatic Cancer Audit. The rate of postoperative pancreatic fistula grade B/C (according to the International Study Group of Pancreatic Surgery 2016 definition) was calculated per risk category. Model performance was assessed using the area under the receiver operating curve (discrimination) and calibration plots. Results: Overall, 3,900 patients were included in risk categories: A (n = 1,046), B (n = 498), C (n = 963), and D (n = 1,393) with corresponding postoperative pancreatic fistula grade B/C rates of 3.8%, 12.2%, 15.6%, and 29.6%. Per category, the in-hospital mortality rates were 1.3%, 3.4%, 2.9%, and 4.1%, P = .001. There was no difference in the rate of postoperative pancreatic fistula between risk categories B and C (12.2% vs 15.6%, P = .101). When simplifying the classification system to a 3-tier classification system (based on 0, 1, and 2 risk factors), the discrimination was not significantly different (area under the receiver operating curve 0.697 vs area under the receiver operating curve 0.701, P = .077). Conclusion: This validation of the 4-tier International Study Group of Pancreatic Surgery risk classification for postoperative pancreatic fistula after pancreatoduodenectomy confirmed its predictive value. However, as the 2 middle risk categories provide no added predictive value, a simplified 3-tier classification with comparable predictive value is proposed and should be validated in future prospective studies.