Evaluating Prescribing Practices of Apixaban in the Elderly

Off-Label Reduced Dose Apixaban in Older Adults With Atrial Fibrillation and Associated Outcomes

BACKGROUND

Apixaban is commonly used to prevent stroke in older adults with nonvalvular atrial fibrillation (AF). Although its package insert has specific dose reduction criteria, providers may dose reduce outside of these parameters based on clinical scenarios.

OBJECTIVE

The primary objective was to determine the incidence of apixaban off-label reduced dosing, while secondarily determining the safety and efficacy outcomes associated with such dosing.

METHODS

A retrospective analysis of patients aged 65 and older with orders for apixaban for AF was institutional review board (IRB)-approved and conducted across 3 academic medical centers. Patients receiving off-label reduced-dose apixaban (ie, "underdosed") were matched to a cohort of patients dosed according to the package insert at the standard dosing (5 mg twice daily) using stratified random sampling. Secondary outcomes included 1-year incidence of major bleeding, clinically relevant non-major bleeding (CRNMB), stroke or transient ischemic attack (TIA), and mortality. The Fisher exact tests were used to compare between-group differences.

RESULTS

Of the 1172 patients meeting initial inclusion criteria, 201 (17%) were dosed off-label, with 175 (15%) "underdosed." The 147 "underdosed" patients with documented follow-up were matched with 139 patients receiving standard Food and Drug Administration (FDA)-labeled dosing. There were no significant differences in incidence of stroke (2.7% vs 2.2%), major bleeding (0% vs 0.7%), and CRNMB (2.7% vs 1.4%) in the off-label reduced dosing versus standard dosing groups. All-cause mortality was higher in the off-label reduced-dose group (16 [10.9%] vs 2 [1.4%], P < 0.05).

CONCLUSION AND RELEVANCE

Older adults with nonvalvular AF are commonly prescribed lower-than-recommended doses of apixaban. However, no significant association was found between empiric off-label reduced dosing and stroke or bleeding outcomes.

Comparing the Efficacy and Safety of Apixaban Versus Warfarin in Morbidly Obese Patients

This study was conducted to evaluate the efficacy and safety of apixaban versus warfarin in morbidly obese patients. A total of 250 morbidly obese patients with a body mass index (BMI) higher than 40 kg/m² or a body weight higher than 120 kg who were on anticoagulation therapy with either apixaban or warfarin for over one month were included in the study. This retrospective cohort, multicenter study was executed using the medical records of 125 morbidly obese patients treated with apixaban, while patients on warfarin were selected using a systemic random sampling to match the sample size of the apixaban group. There was no significant difference between apixaban and warfarin in the development of thromboembolic events and major bleeding. However, incidences of minor bleeding significantly decreased in the apixaban group compared to patients treated with warfarin. This difference was overcome by controlling serum creatinine and nonsteroidal anti-inflammatory drugs (NSAIDs). In conclusion, apixaban efficacy and safety are nearly the same as that of warfarin in morbidly obese patients with a lower incidence of minor bleeding with apixaban. Controlling serum creatinine and NSAIDs use may improve warfarin safety and decrease its complications.