Liver and atherosclerotic risks of patients with cryptogenic steatotic liver disease

In 2023, a new nomenclature of "metabolic associated steatotic liver disease" (MASLD) has emerged by incorporating cardio-metabolic criteria to redefine "non-alcoholic fatty liver disease" (NAFLD). Among steatotic liver disease (SLD), those having no known causes and without any one of cardio-metabolic criteria are deemed to have cryptogenic SLD. This study aims to compare the liver and atherosclerotic risks between MASLD and cryptogenic SLD patients.

We analyzed participants with liver ultrasound data from the Taiwan Bio-Bank cohort, excluding those with positive HBsAg, positive anti-HCV, or "frequent drinker". MASLD involves hepatic steatosis and any of five cardiometabolic risk factors, whereas cryptogenic SLD features hepatic steatosis without these risk factors. Liver fibrosis severity was assessed by using NAFLD fibrosis score (NFS), while atherosclerosis was determined by carotid plaques on duplex ultrasound.

Among 17,595 subjects (age 55.47 ± 10.41; males 31.8%), 7538 participants (42.8%) had SLD, comprising 96.5% of MASLD and 3.5% of cryptogenic SLD. Cryptogenic SLD patients are younger and had a lower percentage of male than those with MASLD. After propensity score matching for age and sex, patients with cryptogenic SLD exhibited milder glucose and lipid profiles, fewer carotid plaques, lower liver steatosis, inflammation, and fibrosis markers than those with MASLD.

In this large population-based study, cryptogenic SLD, the excluded group, occupy only 3.5% in NAFLD patients. It has lower liver and atherosclerotic risks than MASLD, supporting its exclusion from NAFLD and justifying the rationale for the new disease name and diagnostic criteria of MASLD.