The 2012 CKD–EPI creatinine-cystatin C equation is more accurate than the 2009 CKD–EPI creatinine and 2012 CKD–EPI cystatin C equations and it is useful as a confirmatory test for decreased eGFR as determined by serum creatinine-based eGFR (Table 1) (49). This evidence concerns the gene CST3 and chronic kidney disease.