Abstract
Sarcopenia, defined as a loss of skeletal muscle mass and/or function, has been associated with poor survival in various cancers. This study evaluates the prognostic impact of sarcopenia in multiple myeloma (MM) using the Psoas Muscle Index (PMI). A total of 181 MM patients diagnosed between 2014 and 2024 were retrospectively analyzed. Sarcopenia was assessed using PMI measurements at the L3 vertebra level, with gender-specific cut-off values determined by ROC analysis (442.63 mm²/m² for males and 308.85 mm²/m² for females). Sarcopenia was identified in 29.8% of patients. Sarcopenic patients were significantly older, had lower BMI, albumin, and hemoglobin levels, and were less likely to be eligible for transplantation. Multivariate analysis revealed that older age (OR:1.14, 95%CI:1.08-1.32, p = 0.014), hypoalbuminemia (OR:2.13, 95% CI: 1.11-4.12, p = 0.023), and low BMI (OR:2.52, 95%CI:1.83-5.23, p = 0.001) were independent risk factors for sarcopenia. Sarcopenia independently predicted worse PFS (HR:1.628, 95%CI:1.065-2.487, p = 0.024) and OS (HR:2.095, 95%CI:1.207-3.636, p = 0.009). Other independent risk factors for OS included LDH > ULN (HR:2.026, 95%CI:1.130-3.631, p = 0.018), transplant eligibility (HR:0.338, 95%CI:0.191-0.596, p < 0.001), and high cytogenetic risk (HR:1.912, 95%CI:1.004-3.640, p = 0.049). Subgroup analyses showed that sarcopenia significantly affected OS in transplant-ineligible patients (HR:0.501, 95%CI: 0.262-0.957, p = 0.03) but had no significant impact on survival in transplant-eligible patients. Sarcopenia analysis by using PMI in MM patients can be considered a cost-effective, simple, easily applicable, and practical method for daily routine. Sarcopenia independently predicts worse survival outcomes, particularly in transplant-ineligible patients. Larger prospective studies are warranted to validate these findings and explore integrating sarcopenia into frailty indices for MM.