Defining the optimal bilirubin level before hepatectomy for hilar cholangiocarcinoma

In the management of operable hilar cholangiocarcinoma (HC) patients with hyperbilirubinemia, preoperative biliary drainage is a measure to bring down the bilirubin to a certain level so as to avoid adverse postoperative outcomes that would otherwise result from hyperbilirubinemia. A cutoff value of bilirubin level in this context is needed but has not been agreed upon without controversy. This retrospective study aimed to identify a cutoff of preoperative bilirubin level that would minimize postoperative morbidity and mortality.

Data of patients having hepatectomy with curative intent for HC were analyzed. Discriminative analysis was performed to identify the preoperative bilirubin level that would make a survival difference. The identified level was used as the cutoff to divide patients into two groups. The groups were compared.

Ninety patients received hepatectomy with curative intent for HC. Their median preoperative bilirubin level was 23 μmol/L. A cutoff preoperative bilirubin level of 75 μmol/L was derived from Youden's index (sensitivity 0.333; specificity 0.949) and confirmed to be optimal by logistic regression (relative risk 9.250; 95% confidence interval 1.932-44.291; p = 0.005), with mortality shown to be statistically different at 90 days (p = 0.008). Patients were divided into Group A (≤75 μmol/L; n = 82) and Group B (> 75 μmol/L; n = 8). Group B had a higher preoperative bilirubin level (p < 0.001), more intraoperative blood loss (3.12 vs 1.4 L; p = 0.008), transfusion (100% vs 42.0%; p = 0.011) and replacement (2.45 vs 0.0 L; p < 0.001), more postoperative renal complications (p = 0.036), more in-hospital deaths (50% vs 8.5%; p = 0.004), and more 90-day deaths (50% vs 9.8%; p = 0.008). Group A had a longer follow-up period (p = 0.008). The groups were otherwise comparable. Disease-free survival was similar between groups (p = 0.142) but overall survival was better in Group A (5-year, 25.2% vs 0%; p < 0.001). On multivariate analysis, preoperative bilirubin level and intraoperative blood replacement were risk factors for 90-day mortality.

A cutoff value of preoperative bilirubin level of 75 μmol/L is suggested, as the study showed that a preoperative bilirubin level ≤ 75 μmol/L resulted in significantly less blood replacement necessitated by blood loss during operation and significantly better patient survival after surgery.