Preventing stroke in general practice: major room for improvement

One in four patients in primary care is not being adequately treated with anti-coagulation to reduce the high stroke risk associated with a common form of the heart rhythm disorder atrial fibrillation. These are the findings of a report by UK Consultant Cardiologist and Dr Constantinos Missouris and his research team.

Their aim was to assess whether established UK recommendations and guidelines for preventative blood-thinning treatment (thromboprophylaxis) in patients with atrial fibrillation have been adopted in general practice.

They conducted a retrospective study on all 9400 patients in a general practice computer database in Hatfield in the UK to assess the quality of anticoagulation treatment in patients with a recorded diagnosis of atrial fibrillation (AF).

Three out of five of the 180 patients with a diagnosis of AF were treated with the vitamin K antagonist warfarin (107 patients: 59%), one in six patients with aspirin or clopidogrel tablets 31 (17.2%) one in ten with a recent class of anticoagulant (novel oral anticoagulant (NOAC); 19 patients: 11%), and one in eight received none (23 patients:13%). Thirty-seven patients (35%) who were taking warfarin were in the therapeutic range (TTR) for less two-thirds of the time. Forty-five (28%) of the 163 patients who had a high stroke risk score (a CHA2DS2VASc risk score of two or more) were not prescribed a vitamin K antagonist (VKA) or a NOAC. None had a greater estimated risk of bleeding from the treatment than risk of stroke were the treatment not given.

This study demonstrates that one in four patients with non-valvular AF, and at risk of a stroke, is not being adequately treated with an oral anticoagulant in primary care. The majority were treated with warfarin, a third of which had a low TTR. A high proportion of patients were prescribed antiplatelet therapy instead with aspirin or clopidogrel. This is despite overwhelming evidence that VKAs and NOACs, and not aspirin or clopidogrel, improve outcome in patients with non-valvular atrial fibrillation.

This works strongly suggests that regular reviews of GP practice databases of patients health records should be undertaken to
• identify patients at risk of a disabling or fatal stroke event from non-valvular AF;
• check that measures are being taken to initiate anticoagulant therapy;
• monitor that an effective dose of anticoagulant therapy is being given to reduce the risk of stroke.

Reference for full paper
Ioannou A, Metax S, Kassianos G, Missouris CG. Anticoagulation for the prevention of stroke in non-valvular AF in general practice: room for improvement. Drugs in Context 2016; 5: 212295. DOI: 10.7573/212295