Figure 1.

Selection of the study sample. Using a 5% sample of Medicare claims data, we selected all patients with newly diagnosed atrial fibrillation between January 1, 2013, and December 31, 2014. We then excluded patients who were not continuously enrolled in a part D plan during this period and selected those who had CHA ₂ DS ₂ ‐VASc score ≥2 and CHADS ₂ score <2. We collected their claims for oral anticoagulants and classified them according to their use of oral anticoagulation.