nafld_activity_score: NAFLD Activity Score (NAS)

In cliot: Clinical Indices and Outcomes Tools

NAFLD Activity Score (NAS)

Description

Calculates the NAFLD Activity Score (NAS) to assess the severity of Non-Alcoholic Fatty Liver Disease based on liver biopsy findings. The score sums grades for steatosis, lobular inflammation, and hepatocyte ballooning to help distinguish between Non-Alcoholic Steatohepatitis (NASH) and simple steatosis.

Usage

nafld_activity_score(steatosis_grade, lobular_inflammation, hepatocyte_ballooning)

Arguments

steatosis_grade	Numeric (0-3). Percentage of hepatocytes containing fat. 0: <5%. 1: 5-33%. 2: >33-66%. 3: >66%.
lobular_inflammation	Numeric (0-3). Number of inflammatory foci per 200x field. 0: No foci. 1: < 2 foci. 2: 2-4 foci. 3: > 4 foci.
hepatocyte_ballooning	Numeric (0-2). Amount of ballooning degeneration. 0: None. 1: Few balloon cells. 2: Many cells/prominent ballooning.

Value

A list containing:

NAS_Score	The calculated total score (Range 0-8).
Interpretation	Clinical likelihood of NASH.

References

Kleiner DE, Brunt EM, Van Natta M, et al. Design and validation of a histological scoring system for nonalcoholic fatty liver disease. Hepatology. 2005;41(6):1313-1321. doi:10.1002/hep.20701

Examples

# Example 1: NASH Likely
# Steatosis >66% (3), Inflammation >4 (3), Ballooning Many (2)
# Score = 8
nafld_activity_score(3, 3, 2)

# Example 2: Borderline
# Steatosis 5-33% (1), Inflammation <2 (1), Ballooning Few (1)
# Score = 3
nafld_activity_score(1, 1, 1)

cliot documentation built on Dec. 1, 2025, 1:06 a.m.