Three studies [24–26] used the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) formula to estimate eGFR; 6 studies [12, 16–18, 20, 22] used the Modification of Diet in Renal Disease equation (MDRD); 1 study [29] used the Cockroft-Gault equation; 1 study [19] calculated eGFR from serum cystatin C levels and sex-corrected; 1 study [23] used the combined creatinine-cystatin C equation. Here, CST3 is linked to chronic kidney disease.