KDIGO Guidelines and Kidney Transplantation: Is the cystatin-C Based Recommendation relevant?

The KDIGO guidelines propose a new approach to
diagnose chronic kidney disease (CKD) based on
estimated glomerular ®ltration rate (GFR). In patients
with a GFR value comprised between 45 and 59 mL/
min/1.73m2 as estimated by the CKD-EPI creatinine
equation (eGFRcreat), it is suggested to con®rm the
diagnosis with a second estimation using the CKD-EPI
cystatin C-based equations (eGFRcys/eGFRcreat-cys). We
sought to determine whether this new diagnostic
strategy might extend to kidney transplant recipients
(KTR) and help to identify those with decreased GFR. In
670 KTR for whom a measured GFR was available, we
simulated the detection of CKD using the two-steps
approach recommended by the guidelines in comparison
to the conventional approach relying on creatinine
equation. One hundred forty-®ve patients with no
albuminuria had eGFRcreat between 45 and 59 mL/
min/1.73m2. Among them, 23% had inulin clearance
over 60 mL/min/1.73m2 and were thus incorrectly
classi®ed as CKD patients. When applying the Kidney
Disease: Improving Global Outcomes (KDIGO) strategy,
138 patients were con®rmed as having a GFR below
60 mL/min with eGFRcreat-cys. However, 21% of them
were misclassi®ed in reference to measured GFR. Our
data do no not support the use of cystatin C as a
con®rmatory test of stage 3A CKD in KTR.