Association of SARC-F with muscle mass, strength, and quality derived from bioelectrical impedance spectroscopy for sarcopenia assessment

The SARC-F is a 5-item questionnaire screening for patients at risk of sarcopenia. The electrical properties of tissues derived from bioelectrical impedance spectroscopy (BIS), including phase angle (PhA) and intracellular-extracellular water ratio (ICW/ECW) indices, are biomarkers of age-related loss of skeletal muscle quantity and quality. The purpose of the current study was to examine the association between SARC-F and muscle mass, strength, muscle-specific strength, and muscle quality as assessed by BIS and hand grip strength (HGS). Sarcopenia risk was assessed using the SARC-F questionnaire. BIS was used to obtain skeletal muscle mass (SMM) and skeletal muscle mass index (SMI), PhA, ICW/ECW index, membrane capacitance (Cm) and characteristic frequency (fc) for assessing muscle quantity and quality. HGS was evaluated, and muscle-specific strength (HGS/SMM) was calculated. The Pearson correlation coefficient was used to examine the associations between SARC-F scores and each muscle parameter. A total of 205 older adults aged 65-99 years were included in the current cross-sectional analysis. Of those, 142 were community-dwelling healthy older adults (110 women and32 men) and 63 were the older adults living in special nursing homes for the older adults (45 women and 18 men). SARC-F was significantly correlated with SMM, SMI, HGS, and HGS/SMM in both men and women (p < 0.05). SARC-F was also correlated with PhA, ICW/ECW index, Cm, and fc in both men and women (p < 0.001). The SARC-F score was associated with SMM, HGS, HGS/SMM, PhA, ICW/ECW index, Cm, and fc independently of age, sex, height, and BMI. SARC-F is a subjective yet simple assessment tool for muscle mass, strength, and quality relevant to sarcopenia.