Objective: To evaluate the validity of the simplified Modification of Diet in Renal Disease formula (MDRD) and the formulae based upon cystain C (Cys-C) for estimation of glomerular filtration rate (GFR) in Chinese patients with chronic kidney disease(CKD).
Methods: Serum creatinine and serum Cys-C were measured in 412 patients admitted in our hospital for determining the GFR by 99mTc-DTPA plasma clearance (sGFR) method between January 2008 to November 2009, and the difference, limits of agreement, precision and accuracy were calculated.
Result: The estimated GFRs by all the formulae were significantly correlated to the sGFR (P<0.001). The Cys-C formulae 4 and 5 showed better consistence with sGFR than the other formulae. The Cys-C formulae 4 had greater diagnostic precision and accuracy for predicting the renal function. Compared with the other formulae, the Cys-C formulae 4 and 5 had better accuracy in stages 1 to 5 CKD (P<0.001). However, Bland-altman analysis demonstrated that only the Cys-C formulae 5 was well consistent with sGFR, for the limits of agreement was within the professional agreement of 60 ml x min(-1) x 1.73 m(-2).
Conclusion: Compared with the MDRD equation, the Cys-C formulae 4 and 5 has greater advantages in predicting the GFR in Chinese CKD patients. However, the limits of agreement of the formula should be improved by large-sample clinical trials.