Distribution of Fibrosis-4 index and vibration-controlled transient elastography-derived liver stiffness measurement for patients with metabolic dysfunction-associated steatotic liver disease in health check-up

Aims: The multisociety consensus nomenclature has introduced steatotic liver disease (SLD) with diverse subclassifications, which are metabolic dysfunction-associated steatotic liver disease (MASLD), metabolic dysfunction and alcohol-associated steatotic liver disease (MetALD), alcohol-associated liver disease (ALD), specific etiology, and cryptogenic. We investigated their prevalence, as per the new definition, in individuals undergoing health check-ups. Additionally, we analyzed the distribution of Fibrosis-4 (FIB-4) index and vibration-controlled transient elastography (VCTE)-derived liver stiffness measurement (LSM) for MASLD. Methods: In this cross-sectional study, 6530 subjects undergoing a health check-up in Japan were included. Conventional B-mode ultrasound was carried out on all 6530 subjects, and those with MASLD underwent VCTE. Results: The prevalence of SLD was 39.5%, comprising MASLD 28.7%, MetALD 8.6%, ALD 1.2%, specific etiology SLD 0.3%, and cryptogenic SLD 0.7%. Subjects with VCTE-derived LSM >= 8 kPa constituted 2.1% of MASLD. FIB-4 >= 1.3 showed that the sensitivity, specificity, positive predictive value (PPV), and negative predictive value for diagnosing VCTE-derived LSM >= 8 kPa were 60.6%, 77.0%, 5.3%, and 98.9%, respectively. The referral rate to specialists was 23.8% using FIB-4 >= 1.30. "FIB-4 >= 1.3 in subjects <65 years and FIB-4 >= 2.0 in subjects >= 65 years" showed higher PPV (6.7%) and lower referral rate (17.1%) compared with FIB-4 >= 1.3, but the sensitivity (54.5%) did not show adequate diagnostic capability as a noninvasive test for diagnosing VCTE-derived LSM >= 8 kPa. Conclusions: Acknowledging the selection bias in hepatology centers, we undertook this prospective health check-up study. Although the FIB-4 index proves to be a convenient marker, it might not perform well as a primary screening tool for liver fibrosis in the general population (UMIN Clinical Trials Registry No. UMIN000035188).