The association between glomerular filtration rate estimated by multiple methods at dialysis commencement and patient survival in the ideal trial.

Abstract

Background and Aims: The Initiating Dialysis Early and Late (IDEAL) study demonstrated that planned early or late initiation of dialysis, based on the Cockcroft and Gault (CG) estimation of glomerular filtration rate (eGFR), was associated with identical clinical outcomes. This study was a pre-specified analysis examining the association of all-cause mortality with eGFR, measured by the CG,Modification of Diet in Renal Disease (MDRD) or the Chronic Kidney Disease-Epidemiology Collaboration (CKD-EPI) formulae at the time of commencement of dialysis. Method(s): IDEAL trial participants were allocated into tertiles according to the CG, MDRD and CKD-EPI formulae at dialysis commencement. The patient survival was assessed using the Kaplan-Meier method. Result(s): There was no difference in survival among patients when stratified into tertiles of GFR according to the CG formula. However, there was a significant survival benefit in the tertile of patients starting dialysis with the lowest eGFR when the MDRD or CKD-EPI was applied (p < 0.01), independent of correction for body surface area. An increased hazard ratio for death was observed in older females and patients with diabetes and cardiovascular disease independent of the formula used. Conclusion(s): Discrepancies exist in the relationship between eGFR at dialysis commencement and mortality in patients with stage 5 CKD depending on the formula used. Patients commencing dialysis with a higher eGFR were more likely to be older, Caucasian and have a history of ischemic heart disease, suggesting that observational studies demonstrating a survival benefit in patients who start dialysis 'late' is due to reduced comorbidity.