Researchers have developed a simple scoring method to identify nonalcoholic fatty liver disease using easily available clinical and laboratory data, Dr. Anna Kotronen and her colleagues reported.
The authors also devised an equation containing the same variables as this NAFLD liver fat score that can be used to estimate a patient's individual liver fat content as a percentage.
“To our knowledge, the NAFLD liver fat score and equation are the first simple tools allowing prediction of NAFLD and liver fat in humans based on routinely available data,” said Dr. Kotronen of the University of Helsinki and her associates (Gastroenterology 2009; June 12 [doi:10.1053/j.gastro.2009.06.005
The prevalence of NAFLD is estimated to be 20%-30% in the general population, and up to 75% among obese people. Liver function abnormalities are both insensitive and nonspecific markers of the disorder, and the best method for measuring liver fat content—proton magnetic resonance spectroscopy, or 1H-MRS—often is not available in general practice.
The investigators devised their scoring method by characterizing 313 subjects whose liver fat content had been measured using 1H-MRS, and identifying which variables independently predicted NAFLD. They then tested the validity of the method in another 157 subjects who also underwent 1H-MRS.
A total of 359 of the study subjects did not have diabetes, and 111 had type 2 diabetes but had no other known disease except obesity.
The variables of interest were presence of the metabolic syndrome; increased levels of fasting serum insulin, fasting plasma glucose, fasting serum aspartate aminotransferase (AST), and alanine aminotransferase (ALT); and a decreased AST/ALT ratio. The scoring method assigns numerical values to each of these variables and can be calculated online.
The resulting score, if higher than −0.640, predicted NAFLD with a sensitivity of 86% and a specificity of 71%. In the validation group, a cutoff score of −0.640 or higher predicted NAFLD with a sensitivity of 84% and a specificity of 69%.
The data also were used to create a liver fat equation to predict an individual patient's liver fat percentage.
When clinicians use this score to discover which patients with type 2 diabetes have NAFLD, they can better select antihyperglycemic drugs. For example, PPAR-gamma (peroxisome proliferator-activated receptor-gamma) agonists, also known as thiazolidinediones, are known to decrease liver fat content by approximately half, and they also significantly reduce hepatic inflammation, ballooning necrosis, and, possibly, fibrosis in patients who have nonalcoholic steatohepatitis.
No financial conflicts of interest were reported.