Alcoholic Liver Disease/Nonalcoholic Fatty Liver Disease Index for Classification of Patients with Steatotic Liver Disease

Background: Steatotic liver disease (SLD) encompasses metabolic dysfunction-associated steatotic liver disease (MASLD) and alcohol-associated liver disease (AALD) at extremes as well as an overlap group termed MASLD with increased alcohol intake (MetALD). The Alcoholic Liver Disease/Nonalcoholic Fatty Liver Disease Index (ANI) was proposed to differentiate ALD from nonalcoholic fatty liver disease (NAFLD). We analysed the performance of the ANI in differentiating within the SLD spectrum. Methods: In a cross-sectional study at a tertiary care center, 202 adults (>18 years) who were prospectively diagnosed with SLD defined by magnetic resonance imaging-proton density fat fraction > 6.4% were enrolled. Alcohol consumption (AC) was recorded according to thresholds for significant AC: 140-350 g/week (or 20- 50 g/day) for females and 210-420 g/week (or 30-60 g/day) for males. The ANI was calculated, and area under the receiver operating characteristic curve (AUROC) was generated. Results: Of 202 patients (47 years [interquartile range, IQR, 38 to 55], 23.75% females, 77% obese, 42.1% with diabetes, 38.1% hypertensive, 28.7% statin use), 40.5% were ever-alcohol consumers; 120 (59%), 50 (24.7%), and 32 (15.8%) were MASLD (ANI, -3.7 [IQR, -7 to -1.6]; MetALD, - 1.45 [IQR, -2.4 to 0.28]; and AALD, 0.71 [IQR, -1.3 to 4.8], respectively; P< 0.05 for all). The AUROC of the ANI for MASLD and AALD was 0.79 (IQR, 0.72 to 0.84; cut-off < -3.5) and 0.80 (IQR, 0.74 to 0.86; cut-off > -1.49), respectively. The ANI outperformed aspartate transaminase/alanine transaminase (AST/ALT) ratio (AUROC=0.75 [IQR, 0.69 to 0.81]) and gamma glutamyl transpeptidase (GGT) (AUROC=0.74 [IQR, 0.67 to 0.80]). Addition of GGT did not improve model performance (AUCdiff=0.004; P= 0.33). Conclusion: AC is common in MASLD. The ANI distinguishes MASLD and AALD, with individual cut-offs within the intermediate zone indicating MetALD. ANI also outperforms AST/ALT ratio or GGT.