CHA2DS2-VASc Calculator for Atrial Fibrillation
Evaluates ischemic stroke risk in patients with atrial fibrillation
ClinCalc.com » Cardiology » CHADS2-VASc Calculator for Atrial Fibrillation
Press 'Calculate' to view calculation results.
About This Calculator
Unlike the original CHADS2 score, which was based on a retrospective Medicare registry, CHA2DS2-VASc prospectively included patients from multiple countries who were aged 18 years and older.4 Patients were both ambulatory and hospitalized, and were followed for a total of 12 months.
CHADS2-VASc Score and Stroke Risk
Each increase in CHADS2-VASc was shown to predict ischemic stroke rate per year in a linear fashion:
Accuracy of CHADS2 vs. CHADS2-VASc
In a comparison study of multiple risk assessment tools for atrial fibrillation, CHA2DS2-VASc did not seem to outperform CHADS2. To classify the predictive ability of a scoring system, a C statistic is sometimes used. The C statistic is a number between 0.5 (no better than chance) and 1.0 (perfect prediction) indicating predictive ability. In this case, CHADS2 was 0.637 compared to CHADS2-VASc at 0.647.1. A "good" C statistic is usually at least 0.7 or better, indicating than neither system is particularly accurate in predicting stroke risk.
Classification of CHADS2 vs CHADS2-VASc
In both scoring systems, a score of 0 is "low" risk of stroke, 1 is "moderate", and any score above 1 is a "high" risk. The CHADS2-VASc system, with having three more potential variables, inevitably classifies more patients into a high-risk group. As shown in the diagram below, CHADS2-VASc classifies the same patient group into a higher risk category compared to CHADS2.1
Note how the CHADS2-VASc scoring system classifies more patients into the "high risk" category compared to CHADS2.
Gender and the Caveat to CHA2DS2-VASc
In general, a CHA2DS2-VASc score of 1 should warrant strong consideration for full oral anticoagulation.2 The one exception, however, is in patients who have a score of 1 due to gender alone. In these patients (female < 65 years old without other risk factors), antithrombotic therapy should not be given. This special situation may not be intuitive with the CHA2DS2-VASc scoring system.
References and Additional Reading
- Lip GY, Frison L, Halperin JL, Lane DA. Identifying patients at high risk for stroke despite anticoagulation: a comparison of contemporary stroke risk stratification schemes in an anticoagulated atrial fibrillation cohort. Stroke. 2010;41(12):2731-8. PMID 20966417.
- Camm AJ, Lip GY, De Caterina R, et al. 2012 focused update of the ESC Guidelines for the management of atrial fibrillation: an update of the 2010 ESC Guidelines for the management of atrial fibrillation. Eur Heart J. 2012;33(21):2719-47. PMID 22922413.
- Guyatt GH, Akl EA, Crowther M, et al. Executive summary: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines. Chest. 2012;141(2 Suppl):7S-47S. PMID 22315257.
- Lip GY, Nieuwlaat R, Pisters R, et al. Refining clinical risk stratification for predicting stroke and thromboembolism in atrial fibrillation using a novel risk factor-based approach: the euro heart survey on atrial fibrillation. Chest. 2010;137(2):263-72. PMID 19762550.