Chronic inflammation is increasingly recognized as a crucial contributor to sarcopenia pathogenesis, but accurate diagnosis remains a challenge. Our study aims to investigate the relationship between sarcopenia and the Systemic Immune-Inflammation Index (SII), a comprehensive indicator of inflammation. This cross-sectional study enrolled 632 patients. All participants underwent a comprehensive geriatric assessment. Sarcopenia was assessed through the evaluation of handgrip strength and calf circumference. To determine the SII, we used the formula: Platelet count (109/mm3)×Neutrophil count (109/mm3) / Lymphocyte count (109/mm3). The average age of the participants was 74.8 ± 6.4, and 62.3% (n = 394) were female. Patients were grouped as non-sarcopenic and sarcopenic. The non-sarcopenic group had 536 patients (84.8%), while the sarcopenic group comprised 96 patients (15.2%). Sarcopenic patients showed a higher median SII score than the non-sarcopenic group (p < 0.001). Multivariate logistic regression analysis revealed that the SII score was significantly and independently associated with sarcopenia even after adjusting for potential confounding factors (β = 1.002, 95% CI = 1.001–1.003, p < 0.001). The ROC analysis identified the optimal cut-off for SII in predicting sarcopenia as > 765. At this threshold, the negative predictive values were determined to be 88.1%, with a specificity of 88%. SII is significantly associated with sarcopenia in a geriatric outpatient population, and a population-specific SII cut-off may serve as a novel, simple, and practical biomarker for diagnosing sarcopenia.

Sarcopenia, characterized by the loss of skeletal muscle, is assessed using appendicular skeletal muscle mass indices (ASMI). Various international groups propose different ASMI thresholds for assessing sarcopenia. However, the optimal ASMI that correlates best with physical performance measures in older Turkish adults remains unexplored. This study aims to determine which ASMI is most closely associated with physical performance measures, particularly low handgrip strength (dynapenia), in Turkish older adults. The study included 326 individuals aged 60 and above. Comprehensive geriatric assessments were conducted on all participants, along with anthropometric evaluations and body composition analyses. ASMI was calculated by adjusting height squared, weight, and body mass index (BMI). Physical performance was assessed through handgrip strength, gait speed, and the chair stand test. The mean age of the participants was 74 ± 5.77 years, with 59.8% being women and 37.5% having dynapenia. Height-squared adjusted ASMI was not significantly associated with gait speed or the chair stand test. Weight-adjusted ASMI correlated with handgrip strength and gait speed but not with the chair stand test. Both height and weight-adjusted ASMI did not differ significantly between participants with and without dynapenia (p > 0.05). BMI-adjusted ASMI significantly correlated with all physical performance parameters (p < 0.05). Furthermore, in multivariate regression analysis, BMI-adjusted ASMI (OR = 0.028, 95% CI = 0.01–0.31, p = 0.006) was independently associated with dynapenia. The study indicates that ASMI adjusted for BMI shows stronger correlations with all physical performance parameters and is independently associated with dynapenia. Utilizing ASMI adjusted for BMI may improve sarcopenia diagnosis in Turkish older adults.