The clinical relevance of the Nonalcoholic Fatty Liver Disease Activity Score (NAS) in predicting fibrosis progression

• Objective: The NAFLD activity score (NAS) is a newly proposed system to grade the necroinflammatory activity in liver biopsies of NAFLD patients. This study evaluates the usefulness of the NAS in predicting clinical deterioration and fibrosis progression in NAFLD. Methods: One hundred and twenty-nine patients with biopsy proven NAFLD were included in a long-term histological follow-up study. Clinical and histological course were compared between NASH, “borderline NASH”, and “not NASH” patients. Significant fibrosis progression in NAFLD was defined as progression of more than one fibrosis stage or development of end-stage liver disease during follow-up. Results: Eighty-eight patients accepted re-evaluation and 68 underwent repeat liver biopsy. Mean time between biopsies was 13.8 ± 1.2 years (range 10.3-16.3). At baseline, NASH was diagnosed in 2 (1.6%) patients, and at follow-up, in 1 (1.5%) patient. A trend towards higher baseline NAS was seen in patients (n = 7) that developed end-stage liver disease (3.1 ± 0.9 vs. 2.4 ± 1.0; P = 0.062). Baseline NAS was significantly higher in patients with progressive fibrosis (2.9 ± 0.9 vs. 2.2 ± 0.9; P = 0.017), and NAS was independently associated with significant fibrosis progression tested in a multivariate analysis (P = 0.023). However, 18% of patients without NASH progressed significantly in fibrosis stage. Conclusion: Although the NAS is independently associated with future risk of progressive fibrosis in NAFLD, the clinical usefulness of the score is limited due to the significant overlap in clinical development between NAS-score groups.

Nyckelord

Steatohepatitis

Fatty liver

Fibrosis progression

Clinical follow-up

Histopathology

MEDICINE

MEDICIN

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