How do various methods of GFR estimation correlate? A study in a group of Indian volunteer kidney donors

Introduction: Correlation of Glomerular Filtration rate (GFR) obtained by Double Plasma sampling method (DPSM), Single Plasma sampling method (SPSM), Cockcroft Gault method and Gates’ method in prospective voluntary kidney donors.Methods: Fifty-six prospective donors sent for [۹۹mTc]Tc-DTPA renogram were prospectively included. GFR was obtained by Double Plasma sampling, Single Plasma sampling, Cockcroft Gault and Gates’ method using standard protocols. Intra-class ccorrelation coefficient, Pearson correlation coefficient and difference in mean and median GFR between GFR values obtained by DPSM as reference method and other methods were calculated.Results: GFR obtained by SPSM, Cockcroft Gault method and Gates’ method show poor, moderate and good agreement respectively with GFR obtained by DPSM (reference method). There was statistically significant mild positive correlation between GFR obtained by DPSM with GFR obtained by SPSM and statistically significant moderate positive correlation between GFR obtained by DPSM with Cockcroft Gault method and Gates’ method. The mean and median score of GFR obtained by SPSM, Gates’ method and Cockcroft Gault method were lower, higher and significantly higher respectively than GFR obtained by DPSM.Conclusion: GFR obtained by Gates’ method correlates well with Dual Plasma Sampling Method (DPSM, reference standard) and Cockcroft Gault Method overestimates GFR by a large extent amongst prospective voluntary kidney donors.