Application and Comparison of the CHADS2 and CHA2DS2-VASc Risk Scores in a Population with Atrial Fibrillation

pp. 493-497

Abstract

Introduction
The CHADS2 score and the CHA2DS2-VASc score recently adopted by the medical community have been developed with international registry data and are widely used in clinical practice. However, they have not been evaluated in national registries. 
Objectives
The aims of this study were first to evaluate the predictive power of the CHADS2 and CHA2DS2-VASc stroke risk scores in the Atrial Fibrillation Registry conducted by the Argentine Society of Cardiology Research Area and second to compare both scoring systems.
Methods
The Atrial Fibrillation Registry of 2001 was a multicenter, prospective study of all consecutive patients with chronic atrial fibrillation (permanent, persistent) treated in 70 medical centers in Argentina. Demographic data, socioeconomic characteristics, background and clinical features were obtained. A 2-year follow-up was performed to assess stroke rate. For the present analysis patients without anticoagulant  treatment were selected. In this population, the two risk score systems were assessed; a ROC curve was built for each score (reported as c-statistic) and a comparison between both scoring systems was performed.
Results
The study population consisted of 303 patients (49.3%) not receiving anticoagulant therapy. The stroke rate in the selected population was 9.5%. Both scoring systems predicted significant stroke risk. The stroke rate increased as the CHADS2 and the CHA2DS2-VASc scores were higher, and were similar in both risk scales. The CHADS2 and CHA2DS2-VASc scores had c-statistic values of 0.67 (0.55- .78) and 0.69 (0.59-0.78), respectively, without significant differences between them. The score analyses divided into three risk profiles –low, moderate and high– revealed that the predictive power decreased markedly. The c-statistic value of the CHADS2 was 0.63 (95% CI 0.57-0.68) and that of the CHA2DS2-VASc score was 0.57 (95% CI 0.51-0.62), with a slightly better predictive trend  for the CHADS2 score but without statistical significance.
Conclusions
The two scoring systems used to predict stroke in an Argentine population of patients with persistent and permanent atrial fibrillation have a similar predictive power in accordance with results reported in the literature.