LAUSR

BACKGROUND Sarcopenia increases mortality risk in older adults. Loss of skeletal muscle mass is a cardinal feature of sarcopenia. The creatinine-to-cystatin C ratio (CCR) has been suggested as a marker of muscle mass. The present study investigated the usefulness of CCR in discriminating the risk of low muscle mass and weak muscle strength in an elderly population. METHODS The present cross-sectional study included 1,329 apparently healthy community residents aged 60 years or older. The cross-sectional area (CSA) of muscle in the mid-thigh was measured using computed tomography. Clinical data recorded at routine medical check-ups were obtained from each participant's medical record. RESULTS Mean muscle CSA was 109 ± 24 cm2. CCR by quartiles according to sex was strongly associated with muscle CSA (Q1: 104 ± 22, Q2: 108 ± 24, Q3: 110 ± 23, and Q4: 114 ± 25 cm2, F = 10.38, P < 0.001). This association was independent of major covariates (Q1: reference, Q2: β = 0.06, P < 0.001, Q3: β = 0.10, P < 0.001, and Q4: β = 0.17, P < 0.001) even in a sex-separated analysis. Although creatinine alone was independently associated with muscle CSA (F = 5.81, P < 0.001), the association was weaker than that of CCR, particularly in the individuals with renal functional decline. Also, CCR was associated with grip strength independently of muscle CSA. CONCLUSION CCR was a simple marker of low muscle mass and weak muscle strength in older community-dwelling adults.