Probable Sarcopenia and Inflammatory Indices in Very Old Adults (≥80) in Primary Care: The Role of SII and CAR

Objective Sarcopenia, defined as the loss of muscle mass and function associated with aging, significantly impacts the quality of life of elderly individuals. This study investigated the relationship between the risk of sarcopenia and the systemic immune-inflammation index (SII) in elderly individuals aged 80 years and above. Methods Cross-sectional study of 214 adults aged 80 years and older. SARC-F for case-finding; handgrip dynamometry for muscle strength. Probable sarcopenia per EWGSOP2 (< 27 kg men, < 16 kg women). Systemic immune-inflammation index (SII) and C-reactive protein/albumin ratio (CAR) calculated from routine laboratory tests; muscle mass not measured. Results Median handgrip strength was 10 (5–26) kg in probable sarcopenia versus 25 (17–40) kg in non-sarcopenia (p < 0.001). Significant differences in inflammatory parameters were also observed; the systemic immune-inflammation index (SII) and the C-reactive protein/albumin ratio (CAR) were particularly associated with probable sarcopenia. In multivariable analysis, age, sex, serum albumin, neutrophil count, platelet count, and SII emerged as independent predictors. Receiver operating characteristic analysis indicated that SII may serve as a predictor of probable sarcopenia. Conclusion Among very old adults (≥ 80 years), SII was associated with probable sarcopenia and provided modest discrimination. Incorporating SII into primary care screening pathways may support triage of SARC-F/handgrip–positive patients for confirmatory testing and management; longitudinal validation is needed. Trial Registration: This is not a clinical trial.