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Researchers develop index to better identify individuals with hepatic steatosis

Researchers developed a new score called the Framingham steatosis index that more accurately identified patients with hepatic steatosis, according to recent findings published in Clinical Gastroenterology and Hepatology.

“The [Framingham steatosis index (FSI)] is a diagnostic model that includes age, sex, BMI, triglycerides, hypertension, diabetes, and the [alanine aminotransferase to aspartate aminotransferase (ALT/AST)] ratio that was found to be highly predictive of hepatic steatosis in the [Framingham Heart Study (FHS)],” Michelle T. Long, MD, assistant professor of medicine at Boston University School of Medicine, and colleagues wrote. “When using serum aminotransferases to diagnose hepatic steatosis, the ALT/AST ratio predicted hepatic steatosis better than either ALT or AST alone.”

Hepatic steatosis on liver biopsy is currently used to diagnose nonalcoholic fatty liver disease, the researchers wrote. In epidemiologic studies, ALT has been used as a surrogate marker for NAFLD. But in a previous study, ALT/AST ratio, rather than ALT or AST alone, was correlated with degree of liver fat on biopsy. To validate this finding for hepatic steatosis, Long and colleagues aimed to determine the association between the disease and ALT, AST and the ALT/AST ratio. Using what they found, the researchers sought to derive a diagnostic model.

The researchers performed a cross-sectional study of 1,181 participants from the FHS cohort (mean age, 50.3 years). Those with hepatic steatosis were identified between 2008 and 2011. The researchers compared the ability of ALT, AST and ALT/AST to identify individuals with hepatic steatosis by using the c-statistic value. To identify demographic and clinical factors correlated with the disease, the researchers performed a stepwise regression. They used these factors along with other biochemical factors already associated with the disease to develop the FSI, which was validated with data from the third National Health and Nutrition Examination Survey.

They found the prevalence of hepatic steatosis was 26.8%. The measure that identified hepatic steatosis with the highest c-statistic value was ALT/AST ratio (0.728), followed by ALT (0.706) and then AST (0.589). They derived FSI using patient age, sex, BMI, triglyceride level, hypertension, diabetes and ALT/AST ratio. FSI identified those with hepatic steatosis at the highest c-statistic value (0.845). After being applied to the National Health and Nutrition Survey cohort, FSI identified these patients with a c-statistic value of 0.76.

In addition, the researchers wrote that this model was well-calibrated.

“Because the individual components of the FSI are usually readily available, this model significantly improves over currently available diagnostic scores,” the researchers wrote. “In the clinical setting, the FSI may be useful to help identify NAFLD patients or identify patients at high risk for steatosis who may benefit from abdominal imaging.” – by Will Offit

Disclosure: One researcher reports being an employee for Merck.