Author + information
- Janice B. Schwartz, MD∗ ()
- ↵∗Departments of Medicine and Bioengineering & Therapeutic Sciences, University of California, 301 Main Street, 21A, San Francisco, California 94105
Yao et al. (1) reported on novel anticoagulant (NOAC) dosing patterns in patients with atrial fibrillation and outcomes with underdosing and overdosing. A major concern is that, in a study that investigates correct or incorrect dosing and the consequences, the authors have not correctly classified the need for adjustments based on renal function for 2 of the 3 NOACs studied (rivaroxaban and dabigatran). The recommendations for dosage reductions based on renal function for rivaroxaban are for patients with creatinine clearance as estimated by the Cockcroft and Gault formula of <50 ml/min and for dabigatran for patients with creatinine clearance of <30 ml/min. The authors defined renal indications for dose reduction using the estimated glomerular filtration rate (eGFR) in ml/min/1.73 m2 and not creatinine clearance as in U.S. Food and Drug Administration–approved dosing recommendations or as dosed in the randomized clinical trials that led to marketing approval and that define the risk benefit ratios (2,3). Importantly, it has been shown that the eGFR produces higher values than measured or Cockcroft and Gault–estimated creatinine clearance at older ages (4) and may fail to identify 20% to 50% of patients for whom reduced dabigatran and rivaroxaban doses are recommended (5). In Figure 1, this is demonstrated with recent data from patients receiving NOACs at our institution. The investigators likely used the eGFR because body weight is necessary to estimate creatinine clearance and was not in the administrative database they accessed; the investigators acknowledge they could not consider weight, which is 1 of 3 recommended criteria to be considered for classification of the appropriateness of apixaban dosing (1). Thus, the results from Yao et al. (1) as presented likely underestimate higher than recommended dosing of rivaroxaban and dabigatran. They also potentially promote dosing errors in adjusting for renal function during use of rivaroxaban or dabigatran by suggesting eGFR and creatinine clearance are interchangeable in assessing the need for renal dose adjustment of these medications.
Please note: Dr. Schwartz has reported that she has no relationships relevant to the contents of this paper to disclose.
- 2017 American College of Cardiology Foundation
- Yao X.,
- Shah N.D.,
- Sangaralingham L.R.,
- Gersh B.J.
- Schwartz J.