Cross-sectional and longitudinal associations of creatinine-to-cystatin C ratio with sarcopenia parameters in older adults

Abstract Objectives: Accumulating evidence from cross-sectional studies suggests that the serum creatinine-to-cystatin C ratio (CCR) may be a useful biomarker for sarcopenia. This study aimed to assess the cross-sectional and longitudinal associations between CCR and sarcopenia parameters in community-dwelling older adults. Design: Longitudinal study. Setting and Participants: This 6-year prospective cohort study included the repeated measurement data from 1,253 Japanese residents (662 males and 591 females) aged ≥65 years who underwent medical checkups in Kusatsu and Hatoyama, Japan. A total of 4,421 observations were collected. Measurements: The CCR was grouped into quartiles by sex (Q1–Q4) using Q4 as the reference category. Skeletal muscle mass index (SMI) measured using segmental multifrequency bioelectrical impedance analysis, handgrip strength (HGS), usual gait speed (UGS), and maximal gait speed (MGS) were measured repeatedly as sarcopenia parameters. The association between the CCR and changes in SMI, HGS, UGS, and MGS during the 6-year period were analyzed using a linear mixed-effects model. Results: At baseline, SMI, HGS, and MGS were significantly inversely associated with the CCR quartile (P for trend < 0.001). During the 6-year follow-up period, significantly greater declines in SMI (B = −0.01 kg/m2/year; P = 0.044 for group-by-time interaction) and MGS (B = −0.008 m/sec/year; P = 0.041 for group-by-time interaction) were observed in participants with a baseline CCR in Q1 compared with those with a CCR in Q4. The baseline UGS and change in UGS did not differ significantly according to the baseline CCR quartile. Conclusions: CCR can be a useful biomarker for the decline in clinical status and the subsequent risk of reduction in multiple sarcopenia parameters. CCR may identify those at high risk of sarcopenia and lead to early intervention, even in older adults whose physical function is difficult to assess.