No randomized head-to-head comparison between the individual Non-vitamin K Antagonist Oral Anticoagulants (NOAC) exists. The DANNOAC-AF study is a nationwide cluster randomized cross-over study comparing efficacy and safety of the four NOACs, edoxaban, apixaban, rivaroxaban and dabigatran for oral anticoagulation in non-valvular atrial fibrillation across Danish hospitals and cardiology clinics.