Application of GFR-estimating equations in Chinese patients with chronic kidney disease

To evaluate whether the Modification of Diet in Renal Disease (MDRD) equations could be applied accurately to Chinese patients with chronic kidney disease (CKD), glomerular filtration rates (GFRs) estimated by using MDRD equation 7 (7GFR), the abbreviated MDRD equation (aGFR), and the Cockcroft-Gault equation (cGFR) were compared in patients with different stages of CKD.

The study enrolled patients with CKD diagnosed according to the National Kidney Foundation-Kidney Disease Outcomes Quality Initiative guidelines. All patients were older than 18 years and without acute renal function deterioration, edema, skeletal muscle atrophy, or amputation. Sex, age, body height, and body weight were recorded, and plasma creatinine levels were measured by means of Jaffe's kinetic method using a Hitachi 7600 analyzer (Hitachi, Tokyo, Japan; reagents from Roche Diagnostics, Mannheim, Germany). Creatinine, urea, and albumin were measured in a single clinical laboratory. Dual plasma sampling of technetium Tc 99m-labeled diethylene triamine pentaacetic acid plasma clearance was used as the reference standard GFR (sGFR) for comparison of 7GFRs, aGFRs, and cGFRs at different stages of CKD.

The study enrolled 261 patients, including 146 men and 115 women. Causes of CKD included primary or secondary glomerular disease, obstructive kidney disease, chronic tubulointerstitial disease, and others. Values for 7GFR, aGFR, and cGFR were significantly greater than for sGFR in patients with CKD stages 4 to 5 (the lower the sGFR, the greater the difference); whereas 7GFR, aGFR, and cGFR were significantly lower than sGFR in patients with CKD stage 1.

Our results show that in a Chinese population with CKD, MDRD equation 7 and the abbreviated MDRD equation overestimated GFR in patients with CKD stages 4 to 5 and underestimated GFR in those with CKD stage 1. These results indicate that careful modification of these equations may be necessary in Chinese populations with CKD.