Abstract 11900: Should Venous Thromboembolism Patients Treated With DOACs Be Dose Adjusted Like Patients With Atrial Fibrillation: Lessons From Apixaban

Abstract

Introduction: In contrast to atrial fibrillation (AF), dose adjustment of apixaban and other DOACs is not recommended for pts with DVT or PE (VTE). Median DOAC levels were lower in VTE trials (e.g. apixaban 5-mg BID, AF 171 and 103 ng/mL vs. DVT 132 and 63 ng/mL, peak and trough, respectively), the result of a younger, lower weight population with better kidney function. Thus, VTE patients who meet or approach the apixaban dose reduction criteria may have levels far in excess of what’s needed to prevent recurrence. Hypothesis: Apixaban over exposure occurs in VTE pts at risk for elevated apixaban levels. Methods: Patients ≥ 75 yrs of age who had clinical markers that identified them as being at high risk for over exposure, including: 1) apixaban AF dose risk reduction criteria (age ≥ 80, creatinine ≥ 1.5, and wt ≤ 60-kg) and 2) approaching but not meeting dose reduction criteria (e.g. creatine 1.4, weight 65-kg) had a DOAC level measured at their anticoagulation clinic appointment. Levels were determined using liquid chromatography-mass spectrometry. Clinical decisions were made based on the “expected” apixaban levels. Results: Apixaban levels were obtained in 15 male pts. All 10 pts who were initially treated with apixaban 5-mg (2 of whom met the AF dose reduction criteria) had supratherapeutic apixaban levels on 5-mg BID. Of the 5 pts treated initially with apixaban 2.5-mg BID, 3 had adequate apixaban levels, while the other 2 had trough levels that were on the lower side. All 3 pts who met the AF dose reduction criteria (1 treated initially with 2.5-mg) had an adequate apixaban level on 2.5-mg BID. Conclusions: Apixaban treated VTE pts who meet or approach the AF dose reduction criteria are candidates for apixaban dose reduction, especially in light of the fact that peak and trough levels for VTE pts in general are lower than pts with AF.