Validation of a Modified CHA ₂ DS ₂ -VASc Score for Stroke Risk Stratification in Asian Patients With Atrial Fibrillation

Abstract

BACKGROUND AND PURPOSE: The age threshold for an increased stroke risk for patients with atrial fibrillation may be different for Asians and non-Asians. We hypothesized that a modified CHA2DS2-VASc (congestive heart failure, hypertension, age ≥75, diabetes mellitus, prior stroke or transient ischemic attack, vascular disease, age 65-74 years, female) scheme, mCHA2DS2-VASc, which assigned one point for patients aged 50 to 74 years, may perform better than CHA2DS2-VASc score for stroke risk stratification in Asians. METHODS: This study used the Taiwan National Health Insurance Research Database, which included 224 866 newly diagnosed atrial fibrillation patients. The predictive accuracies of ischemic stroke of CHA2DS2-VASc and mCHA2DS2-VASc scores were compared among 124 271 patients without antithrombotic therapies. From the whole cohort, 15 948 patients had a CHA2DS2-VASc score 0 (males) or 1 (females), and 8654 patients had an mCHA2DS2-VASc score 1 (males) or 2 (females). The latter were categorized into 3 groups, that is, no treatment, antiplatelet therapy, and warfarin, and the risks of ischemic stroke and intracranial hemorrhage (ICH) were compared. RESULTS: During a follow-up of 538 653 person-years, 21 008 patients experienced ischemic stroke. The mCHA2DS2-VASc performed better than CHA2DS2-VASc score in predicting ischemic stroke assessed by C indexes and net reclassification index. For 8654 patients having an mCHA2DS2-VASc score of 1 (males) or 2 (females) because of the resetting of the age threshold, use of warfarin was associated with a 30% lower risk of ischemic stroke and a similar risk of ICH compared with nontreatment. Net clinical benefit analyses also favored the use of warfarin in different weighted models. CONCLUSIONS: In this Asian atrial fibrillation cohort, the mCHA2DS2-VASc score performed better than the CHA2DS2-VASc and would further identify atrial fibrillation patients who may derive a positive net clinical benefit from oral anticoagulation.