Glomerular filtration rate was estimated with the Cockcroft-Gault , Chronic Kidney Disease Epidemiology Collaboration ( CKD-EPI ) , and Modification of Diet in Renal Disease ( MDRD ) equations in all randomized patients with available creatinine at baseline ( n = 17 951 ) , and cystatin C-based glomerular filtration rate was estimated in a subpopulation with measurements available ( n = 6190 ) .