More than a quarter of atrial fibrillation patients with a CHADS2 score of one could be reclassified as truly low risk and not given anticoagulation, a new study suggests.
Under current guidance, patients with a CHADS2 score of zero can be offered aspirin and those with a score of one either aspirin or anticoagulants. Those with a score of two or more should be anticoagulated.
The study identified 4,670 patients with a CHADS2 score of one – treated with aspirin 75mg daily with or without clopidogrel – and reclassified them using the newer CHA2DS2-VASc score.
Most of the patients (74%) were reclassified with a CHA2DS2-VASc score of two or more and after 25 years of follow-up their annual incidence of stroke was 2.1%. But the remaining 26%, reclassified with a score of one, had just a 0.9% annual stroke incidence.
Given the risk of bleeding associated with anticoagulants, the authors said it was unlikely these patients would benefit from treatment.
Study lead Dr Michiel Coppens, vascular physician at the Academic Medical Centre in Amsterdam, said: ‘Whereas most guidelines suggest oral anticoagulation is preferred in patients with a CHADS2 score of one, using CHA2DS2-VASc reclassifies 26% of them as low risk and [they] can be treated with aspirin.
‘Conversely, 74% of patients with a CHADS2 score of one who would normally be treated with aspirin may benefit from anticoagulation.’
The use of CHADS2 rather than the newer score in the 2012/13 QOF indicators for atrial fibrillation has been criticised.
Dr Matt Fay, a GPSI in cardiology in Bradford, said: ‘This paper shows that CHA2DS2-VASc shows truly low risk. But what’s also interesting is that if we look at those people with a CHADS2 score of one, most would be reclassified as being in need of an anticoagulant. This suggests the QOF is poorly set with a view that only those with a CHADS2 score of greater than one should always be offered anticoagulants.’
Dr Fay added that the management of stroke risk in patients with atrial fibrillation was undergoing a paradigm shift – looking for the high risk and treating them appropriately with anticoagulation and identifying those at low risk and not treating them.
‘Aspirin has no role here and so we need to find who to intervene with and CHA2DS2-VASc allows us to do this,’ he said.