Nonalcoholic Fatty Liver Disease: Identifying Patients at Risk of Inflammation or Fibrosis
Am Fam Physician. 2017 Jun 15;95(12):796-797.
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Which patients with nonalcoholic fatty liver disease (NAFLD) have a low likelihood of fibrosis or cirrhosis?
NAFLD is defined as hepatic steatosis on imaging or histology in the absence of other etiologies for secondary fat accumulation. It is usually identified during the evaluation of elevated transaminase levels in a patient without heavy alcohol intake, or found incidentally on imaging studies. The estimated median prevalence in the general population is 20% worldwide,1 and is an estimated 10% to 35% in the United States.2 Nonalcoholic steatohepatitis is a subset of NAFLD characterized by hepatic inflammation and evidence of hepatocyte injury with or without fibrosis, and is associated with an increased risk of cirrhosis and hepatocellular carcinoma.2 The prevalence of biopsy-proven nonalcoholic steatohepatitis in U.S. patients with NAFLD is about 3% to 5%.2
Although liver biopsy remains the standard test for diagnosing fibrosis, it is invasive with significant associated risks. Therefore, a noninvasive method for identifying those at low risk of fibrosis in whom liver biopsy can be avoided would be useful.
Several noninvasive scoring systems using readily available parameters have been proposed to identify advanced fibrosis in patients with NAFLD. These include the aspartate transferase to platelet ratio index3; the alanine transferase ratio4; and the BARD score,5 which comprises the weighted sum of three variables (body mass index [BMI] of 28 kg per m2 or more, aspartate transferase to alanine transferase ratio, and the presence of diabetes mellitus). The FIB-4 score has similar variables as the aspartate transferase to platelet ratio index, with the addition of age.6 Finally, the NAFLD fibrosis score includes age, BMI, blood glucose levels, transferase levels, platelet count, and albumin levels.7 It identifies low-, moderate-, and high-risk groups. However, there is no good prospective evidence that identifying and evaluating high-risk groups with liver biopsy leads to improved health outcomes.
Pooled data from a meta-analysis of 13 studies with 3,064 patients compared the diagnostic accuracy of noninvasive clinical scoring systems using liver biopsy as a reference standard.8 Three scoring systems were evaluated: NAFLD fibrosis score; BARD score; and transient elastography (Fibroscan), an ultrasound-based
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This guide is one in a series that offers evidence-based tools to assist family physicians in improving their decision-making at the point of care.
This series is coordinated by Mark H. Ebell, MD, MS, Deputy Editor for Evidence-Based Medicine.
A collection of Point-of-Care Guides published in AFP is available at http://www.aafp.org/afp/poc.
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