Oral anticoagulant (OAC) treatment with either vitamin K antagonists (VKAs) or non-vitamin K antagonist oral anticoagulants (NOACs) is essential in patients with atrial fibrillation for the prevention of stroke or systemic embolism (SE) a condition that happens when a blood clot forms elsewhere in the body and travels through the blood stream to plug another vessel. While there are significant number of real-world publications on the use and outcomes of NOACs for stroke prevention, evidence from routine clinical practice on the use and outcomes of reduced doses of NOACs is scarce. By evaluating routine clinical practice data from national registers in Denmark, Finland, Norway and Sweden, researchers want to gather information about the safety and how well reduced doses of NOACs work in patients with irregularly heartbeats which are not caused by a heart valve problem (non-valvular atrial fibrillation, NVAF). As a primary aim of this study, treatment with low doses of NOACs (Xarelto [generic name rivaroxaban], Eliquis [generic name apixaban] or Pradaxa [generic name dabigatran]) will be compared with VKAs (warfarin) in Nordic patients with NVAF to assess the occurrence of stroke and systemic embolism [effectiveness]) and intracranial hemorrhage a type of bleeding that occurs inside the skull [safety]).

Inclusion Criteria:

• Patients with a qualifying oral OAC dispensed during the study period
• A primary diagnosis indicative of atrial fibrillation during the baseline period

Exclusion Criteria:

• Age < 18 years at index date
• Died on index date
• A diagnosis of valvular disease, pregnancy, transient cause of atrial fibrillation or venous thromboembolism in the baseline period or on the index date
• Hip or knee replacement surgery in the 60 days prior to or on the index date
• A dispensed prescription of heparin or fondaparinux in the 60 days prior to or on the index date
• A diagnosis of end-stage kidney disease or renal replacement therapy in the baseline period or on the index date
• More than one dispensed OAC (any dose of rivaroxaban, apixaban, dabigatran, edoxaban, or warfarin) on the index date
• A dispensed prescription of an OAC (any dose of rivaroxaban, apixaban, dabigatran, edoxaban, or warfarin) during the baseline period

Patients with NVAF who initiate treatment with oral anticoagulants (OACs, either VKAs or NOACs)

Availability of this study's data will later be determined according to Bayer's commitment to the EFPIA/PhRMA "Principles for responsible clinical trial data sharing". This pertains to scope, timepoint and process of data access. As such, Bayer commits to sharing upon request from qualified researchers patient-level clinical trial data, study-level clinical trial data, and protocols from clinical trials in patients for medicines and indications approved in the US and EU as necessary for conducting legitimate research. This applies to data on new medicines and indications that have been approved by the EU and US regulatory agencies on or after January 01, 2014.

Interested researchers can use www.vivli.org to request access to anonymized patient-level data and supporting documents from clinical studies to conduct research. Information on the Bayer criteria for listing studies and other relevant information is provided in the member section of the portal.