Comparative effectiveness of warfarin, dabigatran, rivaroxaban and apixaban in non-valvular atrial fibrillation: A nationwide pharmacoepidemiological study.

OBJECTIVE: To compare effectiveness and safety of warfarin and the direct oral anticoagulants (DOAC) dabigatran, rivaroxaban and apixaban in non-valvular atrial fibrillation in routine care. METHODS: From nationwide registries, we identified treatment-naïve patients initiating warfarin, dabigatran, rivaroxaban or apixaban for non-valvular atrial fibrillation from July 2013 to December 2015 in Norway. We assessed prescription duration using reverse waiting time distribution. Adjusting for confounding in a Cox proportional hazards model, we estimated one-year risks for ischemic stroke, transient ischemic attack (TIA) or systemic embolism, major or clinically relevant non-major bleeding; intracranial; gastrointestinal; and other bleeding. We censored at switch of treatment or 365 days of follow-up. RESULTS: We included 30,820 treatment-naïve patients. Compared to warfarin, the adjusted hazard ratios (HR) for ischemic stroke, TIA or systemic embolism were 0.96 (95% CI 0.71-1.28) for dabigatran, 1.12 (95% CI 0.87-1.45) for rivaroxaban and 0.97 (95% CI 0.75-1.26) for apixaban. Corresponding hazard ratios for major or clinically relevant non-major bleeding were 0.73 (95% CI 0.62-0.86) for dabigatran, 0.97 (95% CI 0.84-1.12) for rivaroxaban and 0.71 (95% CI 0.62-0.82) for apixaban. Statistically significant differences of other safety outcomes compared to warfarin were fewer intracranial bleedings with dabigatran (HR 0.28, 95% CI 0.14-0.56), rivaroxaban (HR 0.40, 95% CI 0.23-0.69) and apixaban (HR 0.56, 95% CI 0.34-0.92); fewer gastrointestinal bleedings with apixaban (HR 0.70, 95% CI 0.52-0.93); and fewer other bleedings with dabigatran (HR 0.67, 95% CI 0.55-0.81) and apixaban (HR 0.70, 95% CI 0.59-0.83). CONCLUSION: After 1 year follow-up in treatment-naïve patients initiating oral anticoagulation for non-valvular atrial fibrillation, all DOACs were similarly effective as warfarin in prevention of ischemic stroke, TIA or systemic embolism. Safety from bleedings was similar or better, including fewer intracranial bleedings with all direct oral anticoagulants, fewer gastrointestinal bleedings with apixaban and fewer other bleedings with dabigatran and apixaban.

Trends in use of warfarin and direct oral anticoagulants in atrial fibrillation in Norway, 2010 to 2015.

PURPOSE: Since 2011, several direct oral anticoagulants (DOACs; dabigatran, rivaroxaban, apixaban) have been introduced as alternatives to warfarin for stroke prophylaxis in atrial fibrillation. We wanted to investigate changes in utilization of oral anticoagulants for atrial fibrillation in Norway following the introduction of DOACs. METHODS: Using nationwide registries, we identified all adults with pharmacy dispensings for warfarin or DOACs between January 2010 and December 2015 in Norway, and used ambulatory reimbursement codes to identify atrial fibrillation as indication. We defined incident use by a 1-year washout period. We describe trends in prevalent and incident use of warfarin and DOACs between 2010 and 2015, as well as patterns of treatment switching for incident users. RESULTS: One hundred twenty-nine thousand two hundred eighty-five patients filled at least one prescription for an oral anticoagulant for atrial fibrillation; the yearly number of incident users increased from 262 to 421 per 100,000 person-years; and the yearly share of incident users who initiated a DOAC increased to 82%. Half the prevalent users were on a DOAC by 2015. Within a year of drug initiation, 6, 12, 16 and 20% of incident users of apixaban, rivaroxaban, warfarin and dabigatran, respectively, switched oral anticoagulant. CONCLUSIONS: Use of DOACs for anticoagulation in atrial fibrillation became more prevalent between 2010 and 2015 in Norway, at the expense of warfarin.