Non-imaging indices for attenuation imaging–defined steatotic liver disease: fatty liver index and hepatic steatosis index

BACKGROUND AND AIM: Ultrasonography is the standard for diagnosing steatotic liver disease (SLD), but its use in population-based health screening is often limited by resource and workflow constraints. We evaluated alanine aminotransferase (ALT) and two non-imaging indices, the Fatty Liver Index (FLI) and Hepatic Steatosis Index (HSI), for screening attenuation imaging (ATT)-defined steatosis. METHODS: We retrospectively analyzed 2,394 adults who underwent health checkups. Abdominal ultrasonography with ATT was optional and performed in participants who elected to undergo it. Steatosis grades were defined using ATT cutoffs (S0-S3), with SLD defined as S1-S3. Diagnostic performance was assessed using area under the receiver operating characteristic curve (AUROC), and screening-oriented thresholds were examined using prespecified rule-out (sensitivity ≥90%) and rule-in (specificity ≥90%) criteria. Screening-oriented thresholds showed negative predictive values of 79.1%-82.3% and positive predictive values of 60.2%-67.4%, indicating modest but clinically useful rule-out and rule-in performance. In lean participants, HSI showed higher discrimination than ALT (AUROC 0.651 vs 0.561), and HSI also remained favorable in women. The advantage of FLI and HSI over ALT was more apparent at earlier steatosis stages than at severe stages. CONCLUSIONS: Using ATT as a quantitative reference, FLI and HSI discriminated ATT-defined SLD better than ALT, supporting their use as practical non-imaging tools for initial screening in routine health screening and primary care settings when ultrasonography is not readily available.