We identified all patients who developed a major complication after HPB surgery according to the following definitions. Hepatic insufficiency was defined according to the definitions of the International Surgical Group of Liver Surgery (ISGLS).23 (link) Postoperative hemorrhage was defined according to the grading system of the ISGLS for patients undergoing hepatectomy and according to the grading system of the International Surgical Group of Pancreatic Surgery (ISGPS) for patients undergoing pancreatectomy because the 2 grading systems are different.24 (link),25 (link) Each of these adverse events was assigned a severity grade of A, B, or C, with A indicating least severe and C indicating most severe complication. Events graded B or C were considered major.
The abdomen was not always drained, and the levels of bilirubin or amylase in effluent were not always measured, so data were not always available to conclusively differentiate bile leaks or pancreatic fistulas from abscesses or sterile collections. As a result, use of the ISGLS and ISGPS definitions alone might underestimate the number of bile leaks and pancreatic fistulas. Therefore, drained fluid collections were also categorized as “fluid collection” and were graded according to the Clavien-Dindo classification. Adverse events other than hepatic insufficiency, fluid collection, and hemorrhage (e.g., cardiac, respiratory, gastrointestinal, neurological, and renal) were categorized as “other complications”. Any complication graded III, IV, or V on the Clavien-Dindo scale was considered major.2 (link)For patients who suffered more than one major complication, the most severe complication was reported unless an alternate complication was clearly the proximal cause of a death. A notable exception was hemorrhage of a pseudoaneurysm associated with pancreatic fistula, in which case fluid collection was reported as the major complication. In rare cases, the most severe complication grade of a patient who did not die a surgery-related death was shared by more than 1 complication. In such cases, the complication that appeared upon complete re-review of the case to have the most clinical significance was reported.
The abdomen was not always drained, and the levels of bilirubin or amylase in effluent were not always measured, so data were not always available to conclusively differentiate bile leaks or pancreatic fistulas from abscesses or sterile collections. As a result, use of the ISGLS and ISGPS definitions alone might underestimate the number of bile leaks and pancreatic fistulas. Therefore, drained fluid collections were also categorized as “fluid collection” and were graded according to the Clavien-Dindo classification. Adverse events other than hepatic insufficiency, fluid collection, and hemorrhage (e.g., cardiac, respiratory, gastrointestinal, neurological, and renal) were categorized as “other complications”. Any complication graded III, IV, or V on the Clavien-Dindo scale was considered major.2 (link)For patients who suffered more than one major complication, the most severe complication was reported unless an alternate complication was clearly the proximal cause of a death. A notable exception was hemorrhage of a pseudoaneurysm associated with pancreatic fistula, in which case fluid collection was reported as the major complication. In rare cases, the most severe complication grade of a patient who did not die a surgery-related death was shared by more than 1 complication. In such cases, the complication that appeared upon complete re-review of the case to have the most clinical significance was reported.
