If you take part, your GP will confirm you are eligible to join the trial and then a computer will decide at random (like tossing a coin) which group you are assigned to:
Group 1: You continue with your current treatment and will start a blood thinning tablet at age 75, or sooner if you have other medical conditions that lead to a high risk of stroke.
Group 2: In addition to any usual treatments, your GP will prescribe a blood thinning tablet called a DOAC (direct oral anticoagulant), with the precise drug you start depending on local NHS policies. In some cases, your GP may stop prescribing drugs you are already taking, such as aspirin.
Once the treatment is assigned, you and your doctor will know which group you are in. In both groups, patients will be followed up automatically to check for strokes, blood clots, heart disease, bleeding episodes and dementia. We will do this by securely linking your NHS medical records (from your GP and hospital records) and medical information stored centrally by NHS Digital and the Office for National Statistics.