MDRD is the eGFR equation most strongly associated with 4-year mortality among patients with diabetes in Colombia

Abstract

Introduction: We compared the association of glomerular filtration rate (GFR) estimated with the Cockcroft-Gault, Modification of Diet in Renal Disease study (MDRD), Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI), or the new CKD-EPI without race (CKD-EPI-NR) equations, with 4-year all-cause mortality in patients with diabetes.

Research design and methods: We analyzed a nationwide, centralized database of all adults diagnosed with diabetes assisted by the Colombian Health System between July 1, 2015, and June 30, 2019. Plasma creatinine was used to calculate baseline estimated glomerular filtration rate (eGFR) and classify each patient in a chronic kidney disease (CKD) stage, by each of the four equations. We used multivariate logistic regression to compare the association between CKD stage and mortality, and receiver operating characteristic (ROC) analyses to assess the overall association of eGFR by each equation and mortality.

Results: The study included 758,219 patients (58% female, 7.2% black race, mean age 62.3, Glycated hemoglobin A1c [HbA1c] 7.4%). There were 35,296 deaths over the study follow-up. Considering eGFR by each equation as a continuous variable, the odds of death decreased by 1.1%-1.5% for each additional mL/min. Compared with CKD stage 1 of each equation, being placed in CKD stages 3a, 3b, or 4 by MDRD or CKD-EPI-NR was associated with greater odds of death than being categorized in the same stages by CKD-EPI. Among patients of black race, the adjusted OR of mortality for CKD stage 4 relative to stage 1 was 4.63 (95% CI 3.39 to 6.35) for MDRD, 3.66 (2.85 to 4.69) for CKD-EPI-NR, 3.01 (2.38 to 3.81) for CKD-EPI, and 2.82 (2.29 to 3.49) for Cockcroft-Gault. The area under the ROC curve to discriminate by survival status was greatest for MDRD, followed by CKD-EPI-NR, CKD-EPI, and Cockcroft-Gault, in that order (p<0.001 for all differences).

Conclusions: Compared with other eGFR equations, MDRD showed the strongest association with all-cause mortality in a sample of Latin-American patients with diabetes. This difference was most pronounced among patients of black race.

Keywords: Diabetes Complications; Kidney Function Tests; Mortality; Race.