Liver steatosis, selected organokines, and cardiovascular risk markers in rheumatoid arthritis.

Background: Metabolic dysfunction-associated steatotic liver disease (MASLD) is seen frequently in rheumatoid arthritis (RA); its often asymptomatic course delays diagnosis. Non-invasive scores and circulating biomarkers may enhance early detection. This study evaluated the prevalence of MASLD, the diagnostic performance of fatty liver index (FLI), hepatic steatosis index (HSI), and selected organokines (fatty acid binding protein 4, brain-derived neurotrophic factor, fetuin-A, and fibroblast growth factor 21) and explored associations of FLI and HSI with organokines, neutrophil-to-lymphocyte ratio, cardiovascular risk scores, and echocardiographic parameters of left ventricular diastolic dysfunction. Materials and methods: This cross-sectional, exploratory study included 51 patients with RA (46 women; mean age 48.8 ± 8.2 years; median disease duration 12 years). The diagnostic value of liver fat scores and organokines for MASLD was assessed by receiver operating characteristic curve analysis. Associations between liver fat scores and organokines, neutrophil-to-lymphocyte ratio, cardiovascular risk scores, and left ventricular diastolic dysfunction parameters were analyzed using univariable linear regression, while relationships with MASLD were evaluated by logistic regression. Results: MASLD was detected in approximately one-third of participants. FLI and fatty acid binding protein 4 demonstrated the best diagnostic discrimination for MASLD in patients with RA [area under the curve (AUC) values of 0.81 and 0.82; Youden index 0.52 and 0.56; cut-off 18.7 and 24.01 ng/mL; sensitivity 93% and 67%, specificity 58% and 89%, respectively]. FLI was positively associated with cardiovascular risk scores and left ventricular diastolic dysfunction parameters. Neutrophil-to-lymphocyte ratio was significantly associated with an increased MASLD risk (OR 2.53, p = 0.03). Conclusions: The FLI and HSI showed moderate-to-good discrimination for ultrasound-defined MASLD, with FLI yielding a numerically higher AUC but without statistically significant superiority over HSI. The FLI showed better performance than the HSI in reflecting cardiovascular risk and abnormalities in left ventricular diastolic function parameters. FABP4 and FGF21 were associated with MASLD-related measures and may warrant further investigation as adjunctive biomarkers. The low exploratory FLI threshold and the association between NLR and MASLD require confirmation in larger, externally validated cohorts using more accurate liver fat quantification and adequately adjusted models.