The DaRe2 approach (healthcare Data for pragmatic clinical Research in the NHS - primary 2 secondary) is designed to operationalise efficient, nationwide, primary care approaches for randomised trials embedded within the UK National Health Service (NHS), providing automated screening, targeted patient enrolment and 'no-visit' follow-up through innovations in big data and technology solutions. DaRe2THINK will be the first exemplar of this system, and is appropriately focused on the intersection of key national priorities for healthcare; atrial fibrillation (a heart rhythm condition that will double in prevalence in the next few decades) and the impact this condition has on stroke, thromboembolic events, cognitive impairment and vascular dementia. The trial will test the hypothesis that direct oral anticoagulants (DOACs), now commonly used in older patients with atrial fibrillation (AF), are effective and cost-effective at reducing major adverse clinical events in younger patients at low or intermediate risk of stroke, and can reduce the high rate of cognitive decline. The health technology innovations noted above will allow the investigators to answer this important clinical question, as well as demonstrate the capacity and potential of this system for future, large-scale healthcare-embedded clinical trials for patient benefit.