Validation of modified estimated glomerular filtration rate in chronic kidney disease patients.

OBJECTIVE To derive the ethnic factor and validate the modified estimated Glomerular Filtration Rate (eGFR) by Modification of Diet in Renal Disease (MDRD) equation for Chronic Kidney Disease (CKD) patients of Rawalpindi. STUDY DESIGN Cross- sectional study. PLACE AND DURATION OF STUDY Armed Forces Institute of Pathology (AFIP), Rawalpindi, from July 2011 to July 2012. METHODOLOGY A total of 140 patients with CKD reporting to AFIP for GFR measurement by 99mTechnetium diethylenethiaminepenta-acetic acid (99mTc-DTPA) renal scan were consecutively inducted. Serum creatinine was measured by the Jaffe's assay on Beckman DxC 600 Analyzer prior to the renal scan. Ethnic factor for population of Rawalpindi with CKD was derived for the MDRD eGFR equation using 99mTc-DTPA renal scan by Gates method as the reference method. MDRD equation was modified by inclusion of the ethnic factor in it. Agreement between the reference GFR (rGFR) and the modified MDRD eGFR (mGFR) was assessed by applying paired samples t-test. RESULTS Out of 140 patients of CKD, 99 (71%) were males and 41 (29%) females, with mean age of 55 ± 13.42 years. The mean values were 32.91 ± 14.96, 34.89 ± 16.45, 0.971 ± 0.20 and 33.87 ± 15.97 for rGFR, original eGFR, ethnic factor and mGFR respectively. The mGFR with new ethnic factor of 0.971 showed improved performance as compared to original eGFR and showed a significant level of correlation with rGFR (r2 = 0.817), at a p-value of 0.000. CONCLUSION This study validates the mGFR equation by inclusion of newly derived ethnic factor of 0.971 in the population of Rawalpindi with CKD and it was found to be not significantly different from the rGFR.