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Background: Pancreatic fistula (PF) is the most common complication following pancreaticoduodenectomy (PD) and is associated with high morbidity. Despite this, few preoperative or perioperative risk factors have been identified. In this study, we measured the postoperative serum amylase level and studied its ability to predict the development of PF.
Methods: A retrospective review of 176 consecutive PD performed by one surgeon between 2006 and 2011 was conducted. Preoperative demographic, perioperative data and clinical outcomes were recorded. Comparison statistics and logistic regression were used to analyze the association between the serum amylase on postoperative day one and the development of PF. PF was defined and scored based on the International Study Group on Pancreatic Fistula.
Results: 146 of 176 consecutive PD cases (83.0%) had serum amylase on postoperative day one recorded. 27 of the 146 developed a PF (18.5%): 6 type A, 19 type B and 2 type C. Patients with a PF had a mean serum amylase on postoperative day one of 659 ± 581 compared to 246 ± 368 in control patients (p<0.001). Patients with leaks were also younger (60.3 ± 11.3 vs 65.5 ± 11.1, p<0.05), less likely to have pancreatic adenocarcinoma (40.7% vs 68.9%, p<0.05) and less likely to have a duct-to-mucosa anastomosis (63.0% vs 88.2%, p<0.01). A serum amylase of 140 U/L, the laboratory's upper limit of normal, was empirically chosen as the cutoff value in order to maximize sensitivity while maintaining specificity. On logistic regression analysis, a serum amylase >140 U/L on postoperative day one was strongly associated with developing a PF (OR 5.48, 95% CI 1.94-15.44) as was receiving an intussuscepting anastomosis (OR 4.41, 95% CI 1.69-11.52). Greater age (OR 0.96, 95% CI 0.93-1.00) and a diagnosis of adenocarcinoma (OR 0.31, 95% CI 0.13-0.71) were associated with not developing PF. Sensitivity and specificity of a postoperative serum amylase >140 U/L was 81.5% and 55.5%, respectively. Positive and negative predictive values were 29.3% and 93.0%, respectively.
Conclusions: An abnormally elevated serum amylase on postoperative day one following PD is associated with a five-fold higher risk of developing a pancreatic fistula. This readily available and inexpensive test may assist in the earlier detection of pancreatic fistula.