The metavir staging system assesses inflammatory changes (histologic activity) and the level of fibrosis as follows (1): Histologic activity A0 = no activity A1 = mild activity A2 = moderate activity A3 = severe activity Fibrosis F0 = no fibrosis F1 = portal fibrosis without septa F2 = portal fibrosis with rare septa F3 = numerous septa without cirrhosis F4 = cirrhosis Blood tests are included in clinical models (eg, APRI index, BARD score, FIB-4 score, nonalcoholic fatty liver disease [NAFLD] fibrosis score), which combine commonly available tests (AST, ALT, platelet count, albumin, INR) with demographic and clinical information (eg, age, body mass index [BMI], diabetes / impaired fasting glucose).