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Design and validation of a histological scoring system for nonalcoholic fatty liver disease
Author(s) -
Kleiner David E.,
Brunt Elizabeth M.,
Van Natta Mark,
Behling Cynthia,
Contos Melissa J.,
Cummings Oscar W.,
Ferrell Linda D.,
Liu YaoChang,
Torbenson Michael S.,
UnalpArida Aynur,
Yeh Matthew,
McCullough Arthur J.,
Sanyal Arun J.
Publication year - 2005
Publication title -
hepatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.488
H-Index - 361
eISSN - 1527-3350
pISSN - 0270-9139
DOI - 10.1002/hep.20701
Subject(s) - steatosis , hepatology , nonalcoholic fatty liver disease , medicine , fibrosis , gastroenterology , fatty liver , cirrhosis , pathology , disease
Nonalcoholic fatty liver disease (NAFLD) is characterized by hepatic steatosis in the absence of a history of significant alcohol use or other known liver disease. Nonalcoholic steatohepatitis (NASH) is the progressive form of NAFLD. The Pathology Committee of the NASH Clinical Research Network designed and validated a histological feature scoring system that addresses the full spectrum of lesions of NAFLD and proposed a NAFLD activity score (NAS) for use in clinical trials. The scoring system comprised 14 histological features, 4 of which were evaluated semi‐quantitatively: steatosis (0‐3), lobular inflammation (0‐2), hepatocellular ballooning (0‐2), and fibrosis (0‐4). Another nine features were recorded as present or absent. An anonymized study set of 50 cases (32 from adult hepatology services, 18 from pediatric hepatology services) was assembled, coded, and circulated. For the validation study, agreement on scoring and a diagnostic categorization (“NASH,” “borderline,” or “not NASH”) were evaluated by using weighted kappa statistics. Inter‐rater agreement on adult cases was: 0.84 for fibrosis, 0.79 for steatosis, 0.56 for injury, and 0.45 for lobular inflammation. Agreement on diagnostic category was 0.61. Using multiple logistic regression, five features were independently associated with the diagnosis of NASH in adult biopsies: steatosis ( P = .009), hepatocellular ballooning ( P = .0001), lobular inflammation ( P = .0001), fibrosis ( P = .0001), and the absence of lipogranulomas ( P = .001). The proposed NAS is the unweighted sum of steatosis, lobular inflammation, and hepatocellular ballooning scores. In conclusion, we present a strong scoring system and NAS for NAFLD and NASH with reasonable inter‐rater reproducibility that should be useful for studies of both adults and children with any degree of NAFLD. NAS of ≥5 correlated with a diagnosis of NASH, and biopsies with scores of less than 3 were diagnosed as “not NASH.” (H EPATOLOGY 2005;41:1313–1321.)