ESTIMATION OF GLOMERULAR FILTRATION RATE IN HEALTHY ADULT PAKISTANI POPULATION: A COMPARISON OF COCKCROFT GAULT AND MODIFIED DIET IN RENAL DISEASE

GFR in Healthy Adult Population

Abstract

Objective: To compare the Cockcroft-Gault (CG) and Modification of Diet in Renal Disease (MDRD) equations of Glomerular filtration rate (GFR) estimation with 24 hours urine creatinine clearance so as to assess their application in clinical practice as a suitable alternative.
Study Design: Cross sectional study.
Place and Duration of Study: This study was carried out at CMH Pano Aqil in 2013.
Material and Methods: This was a cross sectional study conducted to compare results of GFR estimation using 24 hour urine with that of prediction equations based on samples obtained from healthy young adult volunteers. Urine creatinine clearance was measured (mGFR) from 24 hours collected urine sample and serum creatinine of the study subjects. GFR was estimated (eGFR) using standard 4 variable MDRD equation, CG creatinine clearance and CG GFR. The performance of these equations was compared with reference to measured GFR.
Results: Out of 480 persons who consented for evaluation, 426 were included in the study. The subjects were healthy male adults with mean age of 27.86 ± 5.97 years. Mean measured 24 hours urine creatinine clearance was 93.38 ± 13.21 (ml/min/1.73m2). Results showed that MDRD and Cockcroft Gault’s GFR equation underestimated GFR as compared to 24 hour urine evaluation (-0.7 ml/min/1.73m2 and -4.2 ml/min/1.73m2 respectively), while Cockcroft–Gault creatinine clearance equation over estimated by 12.2 ml/min/1.73m2. Overall, MDRD equation fared better with 24 hours urine creatinine clearance than the rest, having a strong correlation (r 0.8795, p<0.0001 and 95% CI of r 0.8561 to 0.8994) and least difference of mean (-0.7 ml/min/1.73m2) by Bland Altman Plots.
Conclusion: We recommend MDRD equation in preference to Cockcroft Gault’s equations to be used for estimation of GFR in clinical practice in young adult Pakistani population. The mean GFR of Pakistani population as of other south Asian is lower than the western population likely due to the racial difference between the two.