The use of the combined CKD-EPI creatinine-cystatin C equation was able to improve reclassification of individuals with creatinine-derived eGFR of 45–74 ml/min/1.73 m2 (net reclassification index 19.4; 95% CI, 8.7 to 30.1; P<0.001), and also 17% of individuals with creatinine-based eGFR of 45–59 ml/min/1.73 m2 to ≥60 ml/min/1.73 m2. Here, CST3 is linked to chronic kidney disease.