The predictive value of five glomerular filtration rate formulas for long-term mortality in patients undergoing coronary artery bypass grafting

Background and Aims: Renal function plays an important role in the management of patients referred for coronary artery bypass grafting (CABG). Current data is insufficient for precise risk stratification using the estimated glomerular filtration rate (eGFR). Methods: This retrospective study includes 3744 consecutive patients who underwent CABG between 2004 and 2020. We assessed five different eGFR formulas: Cockcroft-Gault (CG), modification of diet in renal disease (MDRD), chronic kidney disease Epidemiology Collaboration (CKD-EPI), Mayo, and inulin clearance-based (IB). Results: The Mayo formula yielded the highest mean eGFR (90 +/- 24 ml/min per 1.73m(2)) and CKD-EPI the lowest (74 +/- 21 ml/min per 1.73m(2)). As a result, more patients were classified as having a normal renal function (57%) with the Mayo formula as compared with the others. Using MDRD as the reference formula, there was a significant and stronger correlation between the values obtained from the CKD-EPI (r = .95, p < .001) and Mayo (Mayo: r = .87, p < .001) compared to the IB (r = .8, p < .001) and CG (r = .79, p < .001) formulas. Multivariable analysis demonstrated that decreased renal function is an independent predictor of 10-year mortality in all five formulas, with risk increasing by 13-17% for each 10-unit decrease in eGFR. Despite the similarities between the formulas, the ability to predict mortality was highest in the Mayo formula and lowest in the CG and IB. Conclusions: Our data suggest that the Mayo formula may be superior to the other formulas in prognosticating mortality after CABG. We have shown that the Mayo equation classified fewer individuals as having renal dysfunction and more accurately categorized the risk for mortality than did all other formulas.