Background The Post-operative Morbidity Index (PMI) is a quantitative utility measure of a complication burden created by severity weighting. The Fistula Risk Score (FRS) is a validated model that predicts whether a patient will develop a post-operative pancreatic fistula (POPF). These novel tools might provide further discrimination of the ISGPF grading system. Methods From 2001 to 2012, 1021 pancreaticoduodenectomies were performed at four institutions. POPFs were categorized by ISGPF standards. PMI scores were calculated based on the Modified Accordion Severity Grading System. FRS scores were assigned according to the relative influence of four recognized factors for developing a clinically relevant POPF (CR-POPF). Results In total, 231 patients (22.6%) developed a POPF, of which 54.1% were CR-POPFs. The PMI differed significantly between the ISGPF grades and patients with no or non-fistulous complications (P < 0.001). 64.9% of POPFs and 84.0% of CR-POPFs contributed the highest Accordion grade to the PMI. Overall, the FRS correlated well with PMI (R 2 = 0.81, P < 0.001). Conclusion These data quantitatively reinforce the ISGPF grades that were developed qualitatively around the concept of clinical severity. CR-POPFs usually reflect the patient's highest Accordion score whereas biochemical POPFs are often superseded. The correlation between FRS and PMI indicates that risk factors for a fistula contribute to overall pancreaticoduodenectomy morbidity. © 2013 International Hepato-Pancreato-Biliary Association.