Abstract 2002: Importance of Glomerular Filtration Rate Formula for Determining Chronic Kidney Disease and Clinical Care in Patients with Acute Coronary Syndromes
Background: Assessment of renal function is important for antithrombotic dose adjustment and predicting risk of adverse events in ACS patients (pts). Cockcroft-Gault (C-G) and Modification of Diet in Renal Disease (MDRD) formulae estimate glomerular filtration rate (GFR), yet their correlation in a large ACS population is unknown.
Methods: We estimated renal function (eGFR) using both formulae in 46,942 high-risk ACS pts across 408 CRUSADE hospitals. Agreement between formulae in GFR determination was explored relative to disease staging and its potential impact on need for adjusting antithrombotic dosing based on renal assessment.
Results: Median creatinine was 1.1 (0.9, 1.4) mg/dL. By C-G, the median eGFR was 53.2 mL/min (35,75) and by MDRD it was 65.8 (48,84) mL/min. While GFR estimates based on the 2 forumulae were correlated (R2=0.89), the mean overall variance between them was 10 mL/min; ranging up to 20 mL/min in women ≥75 years old. Up to 20% of pts would be classified as Stage 3 moderate CKD by C-G but not by MDRD (Figure⇓). Type of formula used also had significant impact on whether pts required antithrombotic dose adjustment: among treated pts, dose adjustment recommendations by C-G was nearly double that for MDRD: for eptifibatide (45.7 v 27.3%) and for tirofiban and LMWH (19.0 v 9.6%), respectively. Incidence of major bleeding was higher among pts classified as requiring dose adjustment by C-G but not MDRD.
Conclusions: Estimation of GFR can vary widely depending on the formula used in its calculation, particularly in the elderly. As this has signficant impact on medication dosing and patient safety, more research is needed to determine the best formula for clinical management.