Atrial fibrillation is a common type of irregular heartbeat. Studies have shown that patients with atrial fibrillation have an increased risk of stroke, therefore, most of these patients are provided with ongoing treatment with a blood thinner that is meant to prevent stroke and is recommended lifelong. For years, a medication called warfarin was the main treatment used in atrial fibrillation, but its use is complicated by the need for frequent blood tests to make sure that the concentration of warfarin in the blood is not too high, as this may result in serious bleeding. This limitation has led to the development of another class of drugs, direct oral anticoagulants (DOACs), which do not require monitoring by blood tests. DOACs were introduced in the UK in 2008 as potential alternatives to warfarin, and specifically licenced for atrial fibrillation in 2011. Uncertainty about the real world safety and effectiveness (clinical benefits and harms) of large-scale use of DOACs, however, remains. The purpose of this study is to examine the real world safety and effectiveness of DOACs in patients with atrial fibrillation.
The objective of this study is to assess the safety and effectiveness of different DOACs in patients newly diagnosed with non-valvular atrial fibrillation and treated by anticoagulation. Three matched cohorts, matching on baseline propensity scores, will be built to compare 1) use of Dabigatran vs. Rivaroxaban, 2) use of Dabigatran vs. Apixaban and 3) use of Rivaroxaban vs Apixaban. The investigators will carry out separate population based cohort studies using administrative health databases in Canada, the United States (US), and the United Kingdom (UK). Only new users of anticoagulants (previously unexposed to any oral anticoagulant in the 365 days before) will be included. Cohort entry date will be defined as date of first dispensation/prescription for the oral anticoagulant. Patients will be considered exposed to the drug they received at cohort entry date for their entire follow-up time. The primary outcome will be the relative incidence of a composite of ischemic stroke or systemic embolization. Outcomes will be modelled using Cox Proportional Hazard survival models to estimate the hazard ratios and their corresponding 95% confidence intervals. Similar analyses will be performed separately in different databases according to a common analytical protocol and then pooled using meta-analysis.
Ischemic stroke; Systemic embolization; Major bleeding; Haemorrhagic stroke; All-cause mortality; Myocardial infarction.
Samy Suissa - Chief Investigator - Sir Mortimer B Davis Jewish General Hospital
Christel Renoux - Corresponding Applicant - McGill University
Madeleine Durand - Collaborator - Centre Hospitalier de l'Universite de Montreal
Mireille Schnitzer - Collaborator - University Of Montreal
Pierre Ernst - Collaborator - McGill University
Rui Nie - Collaborator - McGill University
Sophie Dell'Aniello - Collaborator - McGill University
HES Admitted Patient Care