The value of the CHA2DS2-VASc score for refining stroke risk stratification in patients with atrial fibrillation with a CHADS2 score 0–1: A nationwide cohort study

Jonas Bjerring Olesen; Christian Torp-Pedersen; Morten Lock Hansen; Gregory Y. H. Lip

doi:10.1160/TH12-03-0175

Thrombosis and Haemostasis, Table of Contents

Thromb Haemost 2012; 107(06): 1172-1179
DOI: 10.1160/TH12-03-0175

New Technologies, Diagnostic Tools and Drugs

Schattauer GmbH

The value of the CHA₂DS₂-VASc score for refining stroke risk stratification in patients with atrial fibrillation with a CHADS₂ score 0–1: A nationwide cohort study

Authors

Jonas Bjerring Olesen

¹Department of Cardiology, Copenhagen University Hospital Gentofte, Hellerup, Denmark
Christian Torp-Pedersen

¹Department of Cardiology, Copenhagen University Hospital Gentofte, Hellerup, Denmark
Morten Lock Hansen

¹Department of Cardiology, Copenhagen University Hospital Gentofte, Hellerup, Denmark
Gregory Y. H. Lip

²University of Birmingham Centre for Cardiovascular Sciences, City Hospital, Birmingham, UK

Abstract

Summary

North American and European guidelines on atrial fibrillation (AF) are conflicting regarding the classification of patients at low/intermediate risk of stroke. We aimed to investigate if the CHA₂DS₂-VASc score improved risk stratification of AF patients with a CHADS₂ score of 0–1. Using individual-level-linkage of nationwide Danish registries 1997–2008, we identified patients discharged with AF having a CHADS₂ score of 0–1 and not treated with vitamin K antagonist or heparin. In patients with a CHADS₂ score of 0, 1, and 0–1, rates of stroke/ thromboembolism were determined according to CHA₂DS₂-VASc score, and the risk associated with increasing CHA₂DS₂-VASc score was estimated in Cox regression models adjusted for year of inclusion and anti-platelet therapy. The value of adding the extra CHA₂DS₂-VASc risk factors to the CHADS₂ score was evaluated by c-statistics, Net Reclassification Improvement (NRI) and Integrated Discrimination Improvement (IDI). We included 47,576 patients with a CHADS₂ score of 0–1, from these 7,536 (15.8%) were CHA₂DS₂-VASc score=0, 10,062 (21.2%) were CHA₂DS₂-VASc score=1, 14,310 (30.1%) were CHA₂DS₂-VASc score=2, 14,188 (29.8%) were CHA₂DS₂-VASc score=3, and 1,480 (3.1%) were CHA₂DS₂-VASc score=4. Of the cohort with a CHADS₂ score of 0–1, the stroke/thromboembolism rate per 100 person-years increased with increasing CHA₂DS₂-VASc score (95% confidence interval): 0.84 (0.65–1.08), 1.79 (1.53–2.09), 3.67 (3.34–4.03), 5.75 (5.33–6.21), and 8.18 (6.68–10.02) at one year follow-up with CHA₂DS₂-VASc scores of 0, 1, 2, 3, and 4, respectively. Patients with a CHADS₂ score=0 were not all ‘low risk’, with one-year event rates ranging from 0.84 (CHA₂DS₂-VASc score=0) to 3.2 (CHA₂DS₂-VASc score=3). Results from Cox regression analyses, NRI, and IDI confirmed the improved predictive ability of the CHA₂DS₂-VASc score in the AF patients who have a CHADS₂ score of 0–1. In conclusion, the CHA₂DS₂-VASc provides critical information on risk of stroke in AF patients with a CHADS₂ score of 0–1 that can aid a decision of using anti-coagulation. Even in patients categorised as ‘low risk’ using a CHADS₂ score=0, the CHA₂DS₂-VASc score significantly improved the predictive value of the CHADS₂ score alone and a CHA₂DS₂-VASc score=0 could clearly identify ‘truly low risk’ subjects. Use of the CHA₂DS₂-VASc score would significantly improve classification of AF patients at low and intermediate risk of stroke, compared to the commonly used CHADS₂ score.

Note: The editorial process for this article was fully handled by Prof. Christian Weber, Editor-in-Chief.

Keywords

Atrial fibrillation - epidemiology - stroke - risk score

Full Text

References

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