Can the CHA2DS2‐VA schema be used to decide on anticoagulant therapy in Aboriginal and other Australians with non‐valvular atrial fibrillation?

The Australasian guidelines recommend use of the CHA2DS2‐VA schema to stratify ischaemic stroke risk in patients with non‐valvular atrial fibrillation (N‐VAF) and determine risk thresholds for recommending oral anticoagulant (OAC) therapy. However, the CHA2DS2‐VA score has not been validated in a representative Australian population cohort with N‐VAF, including in Aboriginal people who are known to have a higher age‐adjusted stroke risk than other Australians. In a retrospective data‐linkage study of 49 114 patients aged 24–84 years with N‐VAF, 40.0% women and 2.5% Aboriginal, we found that patients with a CHA2DS2‐VA score >2 had high annual stroke rates (>2%) that would justify OAC therapy. This occurred regardless of Aboriginal status. Non‐Aboriginal patients with a CHA2DS2‐VA score of 0 had a mean annual stroke rate of 0.4%, and hence were not likely to benefit from antithrombotic therapy. However, Aboriginal patients with a zero CHA2DS2‐VA score had a significantly higher annual stroke rate of 0.9%, and could potentially obtain net clinical benefit from anticoagulation, primarily with the safer non‐vitamin K antagonist OAC. We conclude that clinicians can confidently use the CHA2DS2‐VA score to make decisions regarding anticoagulation in accordance with stroke risk in patients with N‐VAF, except in Aboriginal people in whom the risk score was unable to identify those at truly low risk of stroke. [ABSTRACT FROM AUTHOR]