Comparison of Stroke Risk Stratification Scores for Atrial Fibrillation

Several stroke risk stratification scores have been developed to guide clinical decision-making in patients with nonvalvular atrial fibrillation (AF). The aim of this study was to compare the performance of the CHADS₂, CHA₂DS₂-VASc and R₂CHADS₂ risk scores to predict stroke. This retrospective cohort study was based on electronic medical records from Clalit Health Services (CHS), the largest payer provider healthcare organization in Israel. Data of CHS members with AF diagnosis between 2004 and 2015 were extracted. Demographic and co-morbidity data were used to calculate the 3 risk scores, and the performance of the scores to predict stroke were compared using area under the curve and net reclassification index. Of the 89,213 CHS members with AF, 52.3% were women and median age was 76 years. The proportions of patients at high risk were 66.2%, 86.7%, and 71.1% in the CHADS_2, CHA₂DS₂-VASc, and R₂CHADS₂, respectively, with stroke incidence rates of 2.91, 2.35, and 2.80 per 100 person-years, respectively. Area under the curves for stroke prediction were 0.61 for both CHADS₂ and CHA₂DS₂-VASc and 0.59 for R₂CHADS₂. Net reclassification index analysis demonstrated a net improvement of 0.089 in the index when CHA₂DS₂-VASc was compared with CHADS₂ and a net reduction of 0.083 when R₂CHADS₂ was compared with CHADS₂. In conclusion, current stroke stratification scores have comparable but limited ability to predict stroke in patients with AF. Stroke prevention strategies may vary depending on the applied stratification. There is a need for a better stroke risk stratification score for patients with AF.