Overdosing and Underdosing of Novel Direct-Acting Oral Anticoagulants

June 20, 2017

Overdosing and Underdosing of Novel Direct-Acting Oral Anticoagulants

  1. Joel M. Gore, MD

Deviations from standard dosing or lack of dose reduction because of renal dysfunction are associated with greater risk for poor outcomes.

  1. Joel M. Gore, MD

When prescribing a direct-acting oral anticoagulant (DOAC) for patients with atrial fibrillation (AF) and poor renal function, physicians need to make downward dose adjustments but do not always do so. Conversely, other patients are prescribed lower doses despite normal renal function. Using claims and laboratory data from a large administrative insurance database, these researchers identified almost 15,000 patients with AF who had initiated apixaban, dabigatran, or rivaroxaban between 2010 and 2015 (median follow-up, 3.6 months).

Among almost 1500 patients with a renal indication for dose reduction, 43% received standard dosing. Analyses using propensity-score matching indicated that standard dosing was associated with higher risk for major bleeding but not with a difference in stroke rate. Among >13,000 patients with no renal indication for dose reduction, 13% received lower-than-standard doses. In analyses by medication, underdosing of apixaban was associated with a fivefold higher stroke risk, compared with standard dosing, but a similar risk for major bleeding. Dose reductions of dabigatran and rivaroxaban were not associated with changes in risks for stroke or bleeding. Multivariable modeling showed that older age was associated with inappropriate underdosing in patients without a renal indication.

Comment

The use of DOACs is not a simple matter of “prescribe and forget.” At the initial DOAC prescription, patients need to be dosed appropriately. Patients prescribed DOACs need to be followed on a regular basis. Adjustments in dose need to be made based on renal and/or liver function. Particular attention needs to focus on not underdosing the elderly.

Editor Disclosures at Time of Publication

  • Disclosures for Joel M. Gore, MD at time of publication Grant / Research support NIH–National Heart, Lung, and Blood Institute

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