Although it is debatable whether “improved CKD” can be defined by an improvement in serum creatinine levels at the second examination, suggested imprecision of creatinine-based GFR compared to cystatin-based GFR within a GFR range of 45 to 59 ml/min/1.73 m2 for predicting outcomes [22], and lack of validation of CKD-EPI equation in older population, the significant decrease of number of complications according to increase of GFR from <60 ml/min/1.73 m2 to ≥60 ml/min/1.73 m2 should be notified. Here, CST4 is linked to chronic kidney disease.