Evaluation of Glomerular Filtration Rate Estimating Equations in CKD Patients With Diabetes and Hypertension

Objective: To compare the performance of Cockcroft-Gault and Modification of Diet in Renal Disease (MDRD) equations in estimating kidney function in CKD patients with diabetes and hypertension. Methods: This study retrospectively reviewed medical records in Hospital Kajang. The GFR was calculated using Cockcroft-Gault and MDRD equations. Kappa Measure of Agreement was used to check the consistency of CKD staging. Wilcoxon signed-ranked tests and Bland-Altman plots were used to determine the difference of both equations. Spearman correlation was used to determine the correlation between blood pressure and blood sugar levels with eGFR. Results: Data pertaining to a total of 81 patients were extracted. Results showed 22% of the patients were staged differently (Kappa value = 0.644 [P<0.001]) and the majority of them moved down one CKD stage when MDRD equation was used instead of Cockcroft-Gault equation. Wilcoxon signed rank test demonstrated there was a significant difference (P<0.001) in eGFR using CandG and MDRD in patients with diabetes and hypertension. Furthermore, the mean difference observed was 3.78±5.56 [P<0.001]), where the Cockcroft-Gault equation measured 3.78 units higher than MDRD equation. However, the relationship between blood sugar and blood pressure with eGFR were not significant. Conclusion: There was a significant difference between Cockcroft-Gault and MDRD equations in estimating kidney function CKD patients with diabetes and hypertension.