The utility of the "NAFLD fibrosis score" in morbidly obese subjects with NAFLD

Obes Surg. 2008 Mar;18(3):264-70. doi: 10.1007/s11695-007-9295-8. Epub 2008 Jan 24.


Background: To date, the noninvasive diagnostic tests for hepatic fibrosis in subjects with nonalcoholic fatty liver disease (NAFLD) have proven to be suboptimal. We evaluated the validity of a recently proposed "NAFLD fibrosis score" to identify liver fibrosis in morbidly obese individuals with elevated and normal alanine aminotransferase (ALT) levels.

Methods: Medical records of 401 patients that underwent a gastric bypass operation and intraoperative liver biopsy were analyzed. Three hundred thirty one patients with biopsy-proven NAFLD were included in the study (group A). These patients were divided into two ALT groups based on their levels according to the new proposed normal range: group B elevated level (ALT > 19 U/L in females and >30 U/L in males, n = 221) and group C normal ALT (n = 110). Diagnostic accuracy of the system was assessed for the presence/absence of any fibrosis, significant fibrosis (stage 2-4), and advanced fibrosis (stages 3 and 4) in all of the groups.

Results: The prevalence of advanced fibrosis in our cohort was about 14%. The low NAFLD fibrosis score demonstrated high accuracy for ruling out advanced fibrosis, with negative predictive value (NPV) of 98 and 99% in groups A and B, respectively. The NPV for significant fibrosis in groups A, B, and C was 87, 88, and 88%, respectively. The respective positive predictive value for the high NAFLD fibrosis score for the presence of any fibrosis was 88, 95, and 77% in groups A, B, and C.

Conclusions: The NAFLD fibrosis score may be a useful noninvasive approach for excluding significant and advanced fibrosis and in morbidly obese patients.

MeSH terms

  • Adult
  • Alanine Transaminase / blood
  • Biopsy, Needle
  • Fatty Liver / complications
  • Fatty Liver / diagnosis*
  • Female
  • Gastric Bypass*
  • Humans
  • Liver / pathology
  • Liver Cirrhosis / complications
  • Liver Cirrhosis / diagnosis*
  • Male
  • Obesity, Morbid / complications*
  • Obesity, Morbid / surgery
  • Predictive Value of Tests


  • Alanine Transaminase