Apixaban for Routine Management of Upper Extremity Deep Venous Thrombosis (ARM-DVT): Methods of a prospective single-arm management study

Background: Upper extremity deep vein thrombosis (UEDVT) constitutes approximately 10% of all deep vein thromboses (DVTs). The incidence of UEDVT is increasing in association with use of peripherally inserted central venous catheters. Treatment for UEDVT is derived largely from evidence for treatment of lower extremity DVT. Limited evidence exists for the use of a direct oral anticoagulant for the treatment of UEDVT. Population: Sequential patients identified within the Intermountain Healthcare System and University of Utah Healthcare system with symptomatic UEDVT defined as the formation of thrombus within the internal jugular, subclavian, axillary, brachial, ulnar, or radial veins of the arm. Intervention: Apixaban 10 mg PO twice daily for 7 days followed by apixaban 5 mg twice daily for 11 weeks. Comparison: The historical literature review rate of venous thrombosis reported for recurrent clinically overt objective venous thromboembolism (VTE) and VTE-related death. If the confidence interval for the observed rate excludes the threshold event rate of 4%, we will conclude that treatment with apixaban is noninferior and therefore a clinically valid approach to treat UEDVT. Sample Size: We elected a sample size of 375 patients so that an exact 95% confidence interval would exclude an event rate of VTE in the observation cohort of 4%. Outcome: Ninety-day rate of new or recurrent objectively confirmed symptomatic venous thrombosis and VTE-related death. The primary safety outcome is the composite of major and clinically relevant nonmajor bleeding.