Relationship of irisin and apelin levels with sarcopenia and body composition in community-dwelling older adults: a paired case-control study.

Irisin and apelin levels continue to decrease with age, and although many previous studies have explored their association with sarcopenia and body composition, there is still a paucity of evidence relating to them in community-dwelling elderly populations. The aim of this study was to provide new evidence for the association of irisin and apelin with sarcopenia in older adults. This case-control study included 80 individuals with sarcopenia and 80 individuals without sarcopenia. The definition of sarcopenia was based on the Asian Working Group for Sarcopenia 2019 criteria. Plasma levels of irisin and apelin were measured using an enzyme-linked immunosorbent assay. Conditional logistic regression analysis was performed to estimate odds ratios (ORs) and 95% CIs. The sarcopenia group exhibited significantly lower levels of irisin (73.75 ± 30.97 ng/mL vs. 131.15 ± 88.38 ng/mL, p < 0.001) and apelin (21.51 ± 14.89 ng/mL vs. 27.87 ± 14.41 ng/mL, p = 0.007) compared to the control group. Increased levels of irisin (OR, 0.98, 95% CI, 0.97-0.99) and apelin (OR, 0.97, 95% CI, 0.95-0.99) were associated with a decreased risk of sarcopenia. In women, irisin was positively associated with body mass index, intracellular water (ICW), extracellular water (ECW), total water (TW), protein, mineral, fat, fat-free mass, skeletal muscle mass (SMM), percentage body fat, waist circumference, visceral fat area, and basal metabolic rate. Apelin was positively associated with ICW, ECW, TW, protein, and SMM (all p < 0.05). In men, positive correlations were found between irisin, apelin, and handgrip strength (all p < 0.05). Receiver operating characteristic analysis showed that irisin and apelin had moderate predictive power in identifying sarcopenia. Plasma irisin and apelin were lower than in controls in elderly patients with sarcopenia, and elevated levels of irisin and apelin were associated with a reduced risk of sarcopenia. In addition, irisin and apelin levels are associated with body composition and irisin showed a stronger ability to predict sarcopenia in women.