Adverse outcomes associated with inappropriate direct oral anticoagulant starter pack prescription among patients with atrial fibrillation: a retrospective claims-based study.

Direct oral anticoagulant (DOAC) starter packs are designed for unique treatment dosing for acute venous thromboembolism (VTE). Inappropriate use of 30-day DOAC starter packs in patients with atrial fibrillation (AF) may increase the risk for bleeding events given higher dosing in the first 1-3 weeks of treatment. A retrospective analysis of medical and outpatient pharmacy claims data from 2015 to 2018 in Optum's De-identified Clinformatics® Data Mart was performed. Patients greater than 18 years of age with AF and a new prescription of apixaban or rivaroxaban were included. Patients with an acute VTE were excluded. The main outcome of interest was adverse events (emergency department [ED] visits, hospitalizations, and deaths within 90 days after prescription fill date) associated with inappropriate DOAC starter pack prescription. A total of 90,950 DOAC-treated patients with AF were identified. The mean age was 74.5 years (SD 10.0) and 42,717 (47.0%) were female. Inappropriate starter packs were used by 117 (0.1%) patients, who were younger than non-starter pack patients (71.3 years vs. 74.5 years). Patients who received an inappropriate DOAC prescription were more likely to identify as Black (12.0% vs. 8.8%). Rates of ED visits, hospitalizations, and deaths overall were numerically lower in patients with starter pack compared to non-starter pack DOAC prescriptions. In contrast, rates of ED visits and hospitalizations related to significant bleeding were numerically higher in patients with starter pack compared to non-starter pack DOAC prescriptions. Among patients with AF but no VTE, those who received an inappropriate DOAC starter pack had numerically higher rates of severe bleeding leading to ED visits and hospitalizations compared to those prescribed an appropriate non-starter pack DOAC anticoagulant.