Comparison of the serum creatinine- and cystatin-C–based indices as screening biomarkers for sarcopenia in community-dwelling older adults

Background: Several creatinine- and cystatin-C–based indices have been proposed as sarcopenia predictors. This study aimed to compare serum creatinine- and cystatin-C–based indices as screening biomarkers for sarcopenia in community-dwelling older adults. Methods: A cross-sectional study was conducted on 945 participants aged between 70 and 84 years (men=47.5%; mean age=76.0 ± 3.9 years) from the Korean Frailty and Aging Cohort Study. The serum creatinine-to-cystatin-C ratio estimated glomerular filtration rate (eGFR) ratio (eGFR_cystatin-C/eGFR_creatinine), sarcopenia index (serum creatinine × eGFR_creatinine), predicted skeletal muscle mass index (pSMI), and total body muscle mass index (TBMM) were compared. Results: The prevalence of sarcopenia was 19.9% in men and 14.0% in women. The pSMI and TBMM showed higher correlations with appendicular lean mass and grip strength in men (pSMI: r_s=0.356–0.701, p < 0.001; TBMM: r_s=0.320–0.730, p < 0.001) and women (pSMI: r_s=0.299–0.669, p < 0.001; TBMM: r_s=0.256–0.658, p < 0.001) than the other indices. The area under the receiver operating characteristic curves (AUC) of the serum indices for predicting sarcopenia showed the highest accuracy for pSMI (men: AUC=0.77, p < 0.001; women: AUC=0.71, p < 0.001). After adjusting for potential confounders, pSMI was associated with the likelihood of sarcopenia in both men (odds ratio [OR]=0.170; 95% confidence interval [CI]=0.103–0.279) and women (OR=0.167; 95% CI=0.087–0.321). Conclusion: pSMI and TBMM accurately determined sarcopenia than the other indices. Furthermore, a higher pSMI was strongly associated with a decreased risk of sarcopenia compared to TBMM. These findings suggest pSMI as a potential biomarker for sarcopenia screening in community-dwelling older adults.