Table 2 NAFLD activity scoring system according to Kleiner et al

NAFLD Activity Score (NAS) (0–8)

 Sum of scores for steatosis, lobular inflammation and hepatocellular ballooning

 ≥5 probable or definite NASH

 3–4 uncertain NASH

 ≤2 no NASH

Steatosis (0–3)

Lobular inflammation (0–3)

Hepatocyte ballooning (0–2)

 0: 5% hepatocytes involved

 0: none

 0: none

 1: 5–33% of hepatocytes involved

 1: <2 foci per × 200 field

 1: few ballooned cells

 2: 33–66% hepatocytes involved

 2: 2–4 foci per × 200 field

 2: many cells/prominent ballooning

 3: >66% hepatocytes involved

 3: >4 foci per × 200 field

Correlation between total NAFLD activity scores and an overall histological diagnosis of steatohepatitis

 NAFLD activity score and histological diagnosis of steatohepatitis

 ≥5 probable or definite NASH

 3–4 uncertain NASH

 ≤2 no NASH