Psoas Muscle Index, Systemic Inflammation, and Liver Fibrosis in MAFLD: A Case-Control Study.

Objective: Investigating psoas muscle index (PMI) as a potential biomarker for metabolic dysfunction-associated fatty liver disease (MAFLD) and hepatic fibrosis through a case-control study.

Methods: This case-control study enrolled 80 MAFLD patients and 80 healthy controls from our hospital (2023-2024). Abdominal CT-derived PMI, inflammatory markers, and FIB-4 scores were assessed. ROC and logistic regression analyses evaluated PMI's diagnostic potential for MAFLD and associated fibrosis.

Results: A total of 160 patients met the inclusion criteria. Compared with the non-MAFLD group, the PMI and systemic inflammatory indicators in the MAFLD group were higher. In MAFLD patients, PMI was significantly correlated with systemic inflammation indicators, including the platelet-to-lymphocyte ratio (PLR), neutrophil-to-lymphocyte ratio (NLR), and systemic immune-inflammation index (SII) (P<0.001, P=0.038, and P<0.001, respectively). ROC curve analysis showed that the areas under the ROC curve (AUC) of PMI and other systemic inflammatory indicators (PLR, NLR, LMR, SII) for diagnosing MAFLD were 0.615, 0.526, 0.956, 0.803, and 0.674, respectively. The AUC of PMI combined with LMR, NLR, and LMR plus NLR for diagnosing MAFLD were 0.547, 0.585, and 0.572, respectively. FIB-4 was linearly correlated with PMI and systemic inflammatory indicators (PLR, NLR, SII) (r=-0.208, P=0.008; r=-0.211, P=0.007; r=0.327, P<0.001; r=0.164, P=0.039). The combination of PMI and systemic inflammatory indicators (PLR, NLR, SII) demonstrated a good diagnostic ability for liver fibrosis in MAFLD (AUC=0.602, P=0.003).

Conclusion: PMI significantly correlates with systemic inflammation and hepatic fibrosis in MAFLD patients, serving as a diagnostic biomarker. Combined with inflammatory markers, it improves non-invasive screening efficacy for MAFLD/fibrosis. This study pioneers incorporating muscle metabolism into MAFLD diagnosis, with potential for primary care translation. Dynamic PMI monitoring may assess "muscle-liver axis" targeted therapies.