Clinical question: Does the Anticoagulation and Risk Factors in Atrial Fibrillation (ATRIA) risk score more accurately identify patients with atrial fibrillation (Afib) who are at low risk for ischemic stroke than the CHADS2 or CHA2DS2-VASc score?
Background: More accurate and reliable stroke risk prediction tools are needed to optimize anticoagulation decision making in patients with Afib. Recently, a new clinically based risk score, the ATRIA, has been developed and validated. This risk score assigns points based on four age categories (as well as an interaction of age and prior stroke); female gender; renal function; and history of diabetes, congestive heart failure, and hypertension. This study compared the predictive ability of the ATRIA risk score with the CHADS2 and CHA2DS2-VASc risk scores and their implications for anticoagulant treatment in Afib patients.
Study Design: Retrospective cohort study.
Setting: Afib patients not using warfarin from the United Kingdom’s Clinical Practice Research Datalink (CPRD) database, January 1998 to January 2012.
Synopsis: A total of 60,594 patients with Afib were followed until occurrence of ischemic stroke, prescription of warfarin, death, or the study’s end. The annualized stroke rate was 2.99%. Patients with moderate and high-risk CHA2DS2-VASc scores had lower event rates than those with corresponding ATRIA and CHADS2 scores. C-statistics for full point scores were 0.70 (95% CI, 0.69–0.71) for ATRIA and 0.68 (95% CI, 0.67–0.69) for both CHADS2 and CHA2DS2-VASc scores. The net reclassification index of ATRIA compared with CHADS2 and CHA2DS2-VASc risk scores were 0.137 and 0.233, respectively, reflecting that the ATRIA risk score better categorizes patients developing an event.
ATRIA risk score more accurately identified low-risk patients than the CHA2DS2-VASc score assigned to higher-risk categories. The results persisted even after restricting analysis to more recent follow-up, excluding unspecified strokes and excluding renal dysfunction as a predictor. Most improvements with ATRIA were the result of “down classification,” suggesting that using the CHA2DS2-VASc risk score could lead to overtreatment of patients at very low risk of stroke.
Bottom line: The ATRIA risk score better identifies Afib patients who are at low risk for stroke compared to CHADS2 and CHA2DS2-VASc scores.
Citation: van den Ham HA, Klungel OH, Singer DE, Leufkens HG, van Staa TP. Comparative performance of ATRIA, CHADS2, and CHA2DS2-VASc risk scores predicting stroke in patients with atrial fibrillation: results from a national primary care database. J Am Coll Cardiol. 2015;66(17):1851-1959.
