Assessing renal function in acute coronary syndromes: does it really matter how we do it?

Abstract

Background: According ESC guidelines renal function should be assessed using estimated Glomerular Rate Filtration (eGRF) calculated using Modification of Diet in Renal Disease (MDRD) equation, although in daily clinical practice Creatinine Clearance (CrCl) calculated with the Cockroft-Gault (CG) formula is more often used. Purpose(s): To assess if eGFR using MDRD equation has more prognostic impact than CrCl calculated with CG formula in acute coronary syndromes (ACS). Population: 2076 patients admitted for ACS between 2004 and 2011 in a Coronary Care Unit. Primary endpoint was death or myocardial infarction in the follow up. Result(s): The mean age of patients was 68+/-13 years and 67.5% were male. Approximately one third of study population (30.5%) had diabetes, 35.6% were elderly and 74.5% had hypertension. Regarding type of ACS, 39.5% of patients had ST elevation; 29.8% of patients reached the primary endpoint in the follow up. Mean admission creatinine was 1.22+/-0.87mg/dL. Mean eGFR was 70.82+/-25.91mL/min/1.73m 2 and mean CrCl was 70.87+/-32.98mL/min. Using MDRD equation, 6.7% of patients had eGFR<30.0mL/min/1.73m 2; otherwise, using CG formula, 9.0% of patients had CrCl<30.0mL/min. Comparing both equation the Concordance Correlation Coefficient was k=0.629 and Spearman Correlation Coefficient was 0.872, with great discrepancy for higher eGFR values. Area under the curve (AUC) of MDRD ROC curve was 0.613 (0.586; 0.639), p<0.001, while AUC of CG curve was 0.614 (0.587; 0.640), p<0.001. Comparing both ROC curves p value was not statistically different (0.888). (figur presented) Conclusion(s): In ACS patients, renal function has an important prognostic value. Although ESC guidelines recommend MDRD formula, CrCl using CG formula has the same prognostic value regarding death or myocardial infarction.