Pharmacotherapy. 2020 Jul 17. doi: 10.1002/phar.2444. Online ahead of print.
BACKGROUND: Anticoagulation monitoring during transition from direct oral anticoagulants (DOAC) to heparin infusions is a significant challenge. Factor-Xa inhibitors influence the heparin calibrated anti-factor Xa assay. The University of Virginia (UVA) Medical Center utilized a corrected anti-factor Xa assay (c-AXA) during this transition period, which removes DOAC-mediated anti-factor Xa activity (d-AXA) and reflects heparin-specific activity. Currently, the duration of this influence is not well described.
OBJECTIVE: This study had two aims: to determine if the initial d-AXA is predictive of the duration of DOAC influence and to further characterize this influence among different patient populations.
METHODS: This retrospective study included adult patients admitted to UVA Medical Center between September 2016 and March 2017, with c-AXA measurements, who received apixaban or rivaroxaban within 48 hours prior to heparin initiation. A Pearson correlation test, Kaplan Meier Survival Analysis, and multivariate linear regression were used to assess the relationship between initial d-AXA and duration of influence.
RESULTS: Sixty-eight patients met inclusion criteria and were maintained on either apixaban (85%) or rivaroxaban (15%) prior to heparin initiation. The initial d-AXA ranged from 0.11 to 3.27 IU/mL. The mean duration of influence was 69.3 ± 46.2 hours, with a median duration of 62.7 hours. No strong correlation was identified between initial d-AXA and duration of influence (R2 =0.124). Presence of interacting medications significantly increased duration of influence (p=0.012). No significant difference in duration of influence existed between patients with normal renal function and those with dynamic renal function (p=0.84), or with BMI > 40 kg/m2 (p=0.16).
CONCLUSION: The initial d-AXA was not predictive of duration of influence in patients transitioning from DOACs to heparin infusion; however, the median duration of influence suggests influence may be present for longer than currently stated in the literature, especially in those taking interacting medications.