Author + information
- †Baylor University Medical Center, Baylor Heart and Vascular Institute, Baylor Jack and Jane Hamilton Heart and Vascular Hospital, Dallas, Texas
- ‡The Heart Hospital, Plano, Texas
- ↵∗Reprint requests and correspondence:
Dr. Peter A. McCullough, Baylor Heart and Vascular Institute, 621 North Hall Street, H030, Dallas, Texas 75226.
- acute kidney injury
- drug dosing
- estimated glomerular filtration rate
- percutaneous coronary intervention
- serum creatinine
Arguably some of the most frequently used numerical values in clinical medicine are calculated or estimated parameters, including left ventricular ejection fraction, low-density lipoprotein cholesterol concentration, and glomerular filtration rate. It has long been recognized that the plasma pool of creatinine, with its skeletal muscle, liver, and dietary determinants, is a relatively crude indicator of global renal filtration and in fact represents glomerular filtration as well as tubular secretion (1). Nevertheless, there has been a wealth of research over the past several decades aimed at devising and promulgating sequentially improved clinical estimates of filtration using primarily the same basic variables: serum creatinine, age, sex, African-American race (a proxy for larger muscle mass), and in some cases, body weight (2). The Cockcroft-Gault equation has been utilized since 1976, and yet it has been criticized for being developed in a small number of subjects and for being influenced by body weight, which in the age of obesity, can yield physiologically implausible high rates (3). The most recent delivery from renal epidemiology is the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation, which is a modest refinement of the 4-variable Modification of Diet in Renal Disease equation and has been demonstrated to be slightly better associated with all-cause mortality in most studies (Figure 1) (4). Importantly, the CKD-EPI equation is standardized to a body surface area of 1.73 m2 and always carries the assumption that the value obtained corresponds to that body surface area.
In this issue of the Journal, Parsh et al. (5) utilized a large database to determine which of the menu of renal filtration function estimates would be potentially most appropriate for cardiac catheterization laboratory drug dosing and to ascertain the associations with acute kidney injury, the need for renal replacement therapy, blood transfusion, and mortality. The Michigan registry of 47 centers reporting consecutive percutaneous coronary intervention cases between January 2010 and March 2014, including 128,805, patients, is an excellent contemporary database to evaluate these pre-procedure equations with respect to clinical outcomes. In general, the CKD-EPI equation performed well and tended to conservatively reclassify patients to lower estimated glomerular filtration rate values relative to the other equations. Importantly, as renal function declined, there appeared to be less agreement among the equations, making the choice of equation in these higher-risk patients an important issue. Because of the reclassification shift between other equations and CKD-EPI, there would be anticipated changes in CKD stage (crossing lines of 60, 30, and 15 ml/min/1.73 m2) that would theoretically affect drug dosing if based on renal function. However, most catheterization laboratories select doses of drugs for sedation, antiplatelet agents, and unfractionated heparin without consideration of renal function. Bivalirudin and enoxaparin (contraindicated at creatinine clearance [CrCl] <30 ml/min) would be most affected by a shift from CrCl to estimated glomerular filtration rate drug dosing in a relatively conservative manner, which would bias care toward a decreased risk of bleeding with both agents. Bivalirudin already performs very well in the setting of CKD (CrCl <30 ml/min, bolus is the same but infusion is reduced from 1.75 to 1.0 mg/kg/h) in comparison to conventionally dosed unfractionated heparin, which is not renal dose adjusted (6).
In summary, the use of the CKD-EPI equation with consistency in hospital laboratory electronic reporting systems and in the catheterization laboratory would have the greatest utility for prognosis of acute kidney injury, bleeding, and mortality. In addition, in a minority of cases, it would help standardize our interpretation of the appropriateness of drug dosing, and it would allow for research of novel drugs that depend on renal clearance to develop doses that have the optimal risk-benefit ratio for patients in stage 3, 4, and 5 not yet requiring renal replacement therapy.
↵∗ Editorials published in the Journal of the American College of Cardiology reflect the views of the authors and do not necessarily represent the views of JACC or the American College of Cardiology.
The authors have reported that they have no relationships relevant to the contents of this paper to disclose.
- American College of Cardiology Foundation
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