Effect of dabigatran on referrals to and switching from warfarin in two academic anticoagulation management services.

Dabigatran was expected to replace warfarin for stroke prevention in patients with nonvalvular atrial fibrillation (AF) who are warfarin naive, difficult to maintain in therapeutic range, or at risk of warfarin-related bleeding complications. We hypothesized that the number of patients with nonvalvular AF referred to Anticoagulation Management Services would decrease sharply and that most would switch from warfarin to dabigatran. We evaluated the number of patients with nonvalvular AF referred to 2 large services, Anticoagulation Management Service 1 and Anticoagulation Management Service 2, 12 months before and after market entry of dabigatran. We also evaluated the number of patients who switched from warfarin to dabigatran. Anticoagulation Management Service 1 follows 1,225 patients with nonvalvular AF with mean CHADS₂ and CHA₂DS₂-VASc scores of 2.0 and 3.5, respectively. Anticoagulation Management Service 2 follows 1,137 patients with nonvalvular AF with mean CHADS₂ and CHA₂DS₂-VASc scores of 2.0 and 3.3, respectively. In the 12 months preceding market entry of dabigatran, patients with nonvalvular AF constituted 537 (31.4%) of the referrals sent to Anticoagulation Management Service 1 and increased to 793 (32.3%) in the following 12 months. For Anticoagulation Management Service 2, patients with nonvalvular AF constituted 617 (30.7%) of referrals before market entry of dabigatran and decreased to 495 (25.2%) of referrals. Eighty-one patients (6.6%) from Anticoagulation Management Service 1 and 44 (3.9%) from Anticoagulation Management Service 2 have switched from warfarin to dabigatran. The frequency of initial prescription of dabigatran for stroke prevention in AF and the frequency of transition from warfarin to dabigatran have been less than expected.