Associations of fat-free mass index and handgrip strength with carotid intima-media thickness among community-dwelling adults aged 60 years and older in Chuncheon, Korea: a cross-sectional study

Background The independent associations of muscle mass and muscle strength with carotid intima-media thickness remain unclear. This study examined the cross-sectional associations of fat-free mass index (FFMI) and handgrip strength with mean carotid intima-media thickness (cIMT) among community-dwelling adults aged 60 years and older in Chuncheon, Korea. We also examined the association between mean cIMT and dynapenia. Methods This cross-sectional analysis used data from the 2007 assessment of the Hallym Aging Study. Among 702 participants who attended the assessment, 611 were aged 60 years or older, and 352 community-dwelling Korean adults with available cIMT, FFMI, atherogenic index of plasma (AIP), and brachial-ankle pulse wave velocity (ba-PWV) measurements were included. FFMI was calculated from bioelectrical impedance analysis-derived fat-free mass divided by height squared. Handgrip strength was measured using a digital dynamometer, and dynapenia was defined using Asian Working Group for Sarcopenia 2019 sex-specific cutoffs. Mean cIMT was the primary outcome, and was measured using high-resolution B-mode carotid ultrasonography. Standardized FFMI and handgrip strength were the primary exposures. Their independent associations with mean cIMT were evaluated using multivariable linear regression with both muscle-related measures entered simultaneously. AIP and ba-PWV were included as adjustment variables in an extended model. The association between mean cIMT and dynapenia was evaluated as a secondary analysis using multivariable logistic regression, with dynapenia as the dependent variable. Results The median age of the 352 participants was 72.0 years, and 49.1% were men. In the primary multivariable model including both standardized FFMI and handgrip strength, each 1-SD increase in FFMI was associated with a 0.035-mm higher mean cIMT (95% CI, 0.014 to 0.056), whereas each 1-SD increase in handgrip strength was associated with a 0.034-mm lower mean cIMT (95% CI, − 0.064 to − 0.004). In the secondary analysis, higher mean cIMT was associated with greater odds of dynapenia (OR = 1.23 per 0.1-mm increase; 95% CI, 1.06 to 1.43). Conclusions Among community-dwelling adults aged 60 years and older, higher FFMI and greater handgrip strength were associated with higher and lower mean cIMT, respectively, after multivariable adjustment.