Regarding  postoperative  liver failure, only two studies6, 14 pointed out that they adopted the “50-50 criteria”  (prothrombin time < 50% and  serum bilirubin > 50 μmol/L on postoperative day 5) to define this outcome indicator, however, the other studies in our analysis failed to give the definition. Here, F2 is linked to Hepatic failure.