Comparison between Three Different Equations for the Estimation of Glomerular Filtration Rate in Omani Patients with Type 2 Diabetes Mellitus

Abstract

Objectives: Estimated glomerular filtration rate (eGFR) is an important component of a patient’s renal function profile. The Modification of Diet in Renal Disease (MDRD) equation and the Chronic Kidney Disease- Epidemiology Collaboration (CKD-EPI) equation are both commonly used. The aim of this study was to compare the performance of the original MDRD₁₈₆, revised MDRD₁₇₅ and CKD-EPI equations in calculating eGFR in type 2 diabetes mellitus (T2DM) patients in Oman. Methods: The study included 607 T2DM patients (275 males and 332 females, mean age ± standard deviation 56 ± 12 years) who visited primary health centres in Muscat, Oman, during 2011 and whose renal function was assessed based on serum creatinine measurements. The eGFR was calculated using the three equations and the patients were classified based on chronic kidney disease (CKD) stages according to the National Kidney Foundation Kidney Disease Outcomes Quality Initiative guidelines. A performance comparison was undertaken using the weighted kappa test. Results: The median eGFR (mL/min/1.73 m²) was 92.9 for MDRD₁₈₆, 87.4 for MDRD₁₇₅ and 93.7 for CKD-EPI. The prevalence of CKD stage 1 was 55.4%, 44.7% and 57% while for stages 2 and 3 it was 43.2%, 54% and 41.8%, based on MDRD₁₈₆, MDRD₁₇₅ and CKD-EPI, respectively. The agreement between MDRD₁₈₆ and CKD-EPI (к 0.868) was stronger than MDRD₁₈₆ and MDRD₁₇₅ (к 0.753) and MDRD₁₇₅ and CKD-EPI (к 0.730). Conclusion:The performances of MDRD₁₈₆ and CKD-EPI were comparable. Considering that CKD-EPI-based eGFR is known to be close to isotopically measured GFR, the use of MDRD₁₈₆ rather than MDRD₁₇₅ may be recommended.