PB0466 - Physician practice behaviors surrounding dose-reduction of direct oral anticoagulants for the extended phase treatment of venous thromboembolism

Background: Two direct oral anticoagulants (DOACs), apixaban and rivaroxaban, have been studied in reduced doses for extended-phase treatment of venous thromboembolism (VTE). However, scant evidence exists surrounding clinician practice and decision-making regarding dose reduction for extended-phase treatment of VTE.

Aims: Report clinician practice and characteristics surrounding dose-reduction of DOACs for extended-phase VTE treatment.

Methods: We conducted a 16-question REDCap survey between 7/14/2021 and 9/13/2021 among ISTH 2021 Congress attendees, and online via Twitter™. We performed logistic regression to explore factors associated with dose-reduction. Considering dosing behaviors, we used k-means clustering and minimized the silhouette score while maintaining sufficient cluster size. We assessed for clustering of clinicians by characteristics around dose reduction decision-making. Descriptive statistics were used to describe the clusters.

Results: 171 clinicians responded, of whom most were attending academic physicians that practiced in North America (Table 1). Clinicians who treated larger volumes of patients had higher odds of electing dose-reduction. We identified 5 clusters that showed distinct patterns of behavior regarding dose-reduction. Cluster 1) Rarely dose reduces and is the cluster most likely to prescribe rivaroxaban; Cluster 2) Dose reduces with considerable frequency, does not consider age when dose-reducing, is least likely to temporarily re-escalate dosing, and prescribes apixaban and rivaroxaban equally; Cluster 3) Dose reduces < 50% of the time, but temporarily re-escalates dosing during increased VTE risk; Cluster 4) Dose reduces with considerable frequency, temporarily re-escalates dosing during increased VTE risk, and is most likely to prescribe apixaban; Cluster 5) Dose reduces with highest frequency, and takes the fewest risk factors into consideration to not dose reduce (Figure 1).

Conclusion(s): Most clinicians elect to dose-reduce DOACs for extended-phase anticoagulation. The likelihood of a clinician to dose-reduce increased with volume of patients treated. Clinician prescribing patterns clustered around VTE risk factors as well as re-escalation during high-risk periods.