Serum cystatin C to creatinine ratio is associated with sarcopenia in non-dialysis-dependent chronic kidney disease

Abstract

Background: Sarcopenia is a prevalent complication in patients with chronic kidney disease and is associated with poor quality of life, morbidity, and mortality. Several candidate biomarkers have been evaluated for this condition. This study assessed the serum cystatin C to creatinine (serum cystatin C/Cr) ratio as a potential biomarker for sarcopenia in patients with non-dialysis-dependent chronic kidney disease.

Methods: This study enrolled 517 outpatients. Muscle mass (lean tissue index) was measured using a bioimpedance spectroscopic device, and muscle strength (handgrip strength) was also measured. Sarcopenia was defined as a combination of low muscle strength and low muscle mass.

Results: Sarcopenia was observed in 25.5% of patients, and the mean serum cystatin C/Cr ratio was significantly higher in patients with sarcopenia than in those without it (1.14 ± 0.26 vs. 1.01 ± 0.27, p < 0.001). The prevalence of sarcopenia and low lean tissue index increased as the cystatin C/Cr ratio increased. The negative predictive value of the cystatin C/Cr ratio for sarcopenia or low lean tissue index was ≥80%. Multivariate analyses revealed that when the serum cystatin C/Cr ratio increased by 1, the risk of sarcopenia, low lean tissue index, and low handgrip strength increased by 4.6-, 7.2-, and 2.6-fold, respectively (p = 0.003, p < 0.001, and p = 0.048). The association was maximized in patients with an estimated glomerular filtration rate of <30 mL/min/1.73 m2.

Conclusion: Calculating the serum cystatin C/Cr ratio could be helpful for detecting and managing sarcopenia in patients with chronic kidney disease.

Keywords: Body composition; Chronic kidney diseases; Creatinine; Cystatin C; Sarcopenia.

Figure 1.. Comparison of serum cystatin C/Cr ratio in patients with and without sarcopenia.

When patients were classified according to age (A), sex (B), eGFR (C), and BMI (D), the cystatin C/Cr ratio was higher in patients with sarcopenia than in those without sarcopenia, except for patients with eGFR of ≥45 or <60 mL/min/1.73 m² and BMI of <23 or ≥30 kg/m². Data are presented as median (interquartile range). BMI, body mass index; Cr, creatinine; eGFR, estimated glomerular filtration rate; NS, not significant. ^*p < 0.05, ^**p < 0.01, ^***p < 0.001.

Figure 2.. Receiver operating curve analysis of sarcopenia, low LTI, and low HGS with serum cystatin C/Cr ratio.

The areas under the receiver operating characteristic curve for the cystatin C/Cr ratio to predict sarcopenia (A), low LTI (B), and low HGS (C) were 0.66 (95% confidence interval [CI], 0.61–0.71; p < 0.001), 0.693 (95% CI, 0.64–0.74; p < 0.001), and 0.65 (95% CI, 0.60–0.70; p < 0.001), respectively. AUC, area under the curve; Cr, creatinine; HGS, handgrip strength; LTI, lean tissue index.