Certain routine demographic, clinical, and laboratory values can be used to identify advanced fibrosis in patients with nonalcoholic fatty liver disease (NAFLD).
This method could render liver biopsy unnecessary in a large proportion of patients.These findings are published in the April issue of Hepatology, the official journal of the American Association for the Study of Liver Diseases (AASLD). Published by John Wiley & Sons, Inc., Hepatology is available online via Wiley InterScience.
The prevalence of NAFLD has risen in conjunction with obesity, diabetes, and the metabolic syndrome. It is the world's most common cause of chronic liver disease and afflicts one in three American adults, and one in ten American children or adolescents. NAFLD may progress to cirrhosis, liver failure, and hepatocellular carcinoma, especially in patients with more advanced fibrosis. Liver biopsy is currently the only reliable way to determine the severity of fibrosis. However, it is an expensive, invasive procedure.
Researchers led by Paul Angulo, MD, of the Mayo Clinic Foundation in Rochester, Minnesota, sought to develop a noninvasive way to determine advanced fibrosis in NAFLD patients using routinely determined and easily available clinical and biochemical variables. They studied 733 patients who had been diagnosed with NAFLD between 2000 and 2003, and who had undergone liver biopsies. For each patient, they collected demographic, clinical, and laboratory data. They used data from 480 patients to build a statistical model that predicted advanced liver fibrosis. They then tested the model using data from the remaining 253 patients.
They found that age, hyperglycemia, body mass index, platelet count, albumin, and AST/ALT ratio were independent indicators of advanced liver fibrosis. They incorporated these factors into a model that yielded a patient's NAFLD fibrosis score. When the model was applied to the validation group, it identified the presence or absence of advanced fibrosis in nearly three out of every four patients.
"By applying the NAFLD fibrosis score, liver biopsy could have been avoided in 75 percent of patients in the total cohort," the authors report. Only 25 percent of the patients, those identified as indeterminate," would have needed a liver biopsy to determine severity of fibrosis.
Limitations of this study may include referral bias, since patients came from centers with a particular interest studying NAFLD, and also differences in pathologist readings. However, its strengths include a large cohort of patients from a variety of locations and backgrounds with a wide-ranging prevalence of fibrosis severity.
"In summary, we have demonstrated that a NAFLD fibrosis score constructed from routine clinical and laboratory variables can accurately predict the presence or absence of advanced fibrosis in NAFLD rendering liver biopsy unnecessary in the vast majority of patients," the authors conclude. "It has to be determined however, whether the addition of serum markers of fibrosis or imaging modalities increases the diagnostic accuracy of the NAFLD fibrosis score."
Future studies should validate their results, include patients of different ages and ethnicities, and determine the potential benefits of diagnosing advanced fibrosis using the model.