Performance of the Cockcroft-Gault, MDRD and CKD-EPI Formulae in Non-Valvular Atrial Fibrillation: Which one Should be Used for Risk Stratification?

Background: Renal dysfunction is a strong predictor of adverse events in patients with atrial fibrillation (AF). The Cokcroft-Gault, Modification of Diet in Renal Disease (MDRD) and Chronic Kidney Disease-Epidemiology Collaboration (CKD-EPI) equations are available for estimating the glomerular filtration rate (GFR). No comparisons between these equations have yet been performed in patients with non-valvular AF concerning their mid-term prognostic performance. Methods: Cross-sectional study of 555 consecutive patients with non-valvular AF undergoing transesophageal echocardiogram. We tested the prognostic performance of the aforementioned GFR estimation formulae, namely their ability to predict all-cause mortality (primary endpoint) and major cardiac adverse or ischemic cerebrovascular events (secondary endpoints) during an average follow-up of 24 months. Results: Regarding the primary endpoint, Cockcroft-Gault (AUC=0.749±0.028) was superior to both MDRD (AUC=0.624±0.039) and CKD-EPI (AUC=0.641±0.034) [p<0.001 both comparisons] while CKD-EPI was superior to MDRD (p=0.011). Cockcroft-Gault was marginally superior to both MDRD (AUC=0.673±0.049 vs. AUC=0.586±0.054, p=0.041) and CKD-EPI (AUC=0.673±0.049 vs. AUC=0.604±0.054, p=0.063) in the prediction of ischemic cerebrovascular events, while no difference was found between CKD-EPI and MDRD. Concerning AUC for prediction of MACE, Cockcroft-Gault was superior to MDRD (p=0.009) and CKD-EPI (p=0.012), while CKD-EPI was similar to MDRD (p=0.215). Multivariate predictive models consistently included Cockcroft-Gault formula along with CHADS2, excluding the other two equations. Measures of reclassification revealed a significant improvement in risk stratification for all studied endpoints with Cockcroft-Gault instead of CKD-EPI. Conclusions: In patients with non-valvular AF, the Cockcroft-Gault more appropriately classified individuals with respect to risk of all-cause mortality, ischaemic cerebrovascular event and major adverse cardiac event.