F2 and chronic hepatitis B virus infection: Twenty-seven patients with acute exacerbation of chronic hepatitis B (CHB) (defined by: alanine transaminase ≥ 20 ULN, total bilirubin ≥ 5 ULN, 40% < prothrombin time activity ≤ 60%) and without cirrhosis were divided into 18 cases which did not progress to HBV-ACLF (defined by: prothrombin time activity < 40% and development within four weeks of hepatic encephalopathy and/or ascites) and nine cases that developed HBV-ACLF.