CDR Blog

The CHA2DS2-VASc score is an updated form of the CHADS2 score, which uses known risk factors to predict the probability of a person with atrial fibrillation developing a stroke(1). These stroke risk factors include hypertension, heart failure, diabetes, age 65-75, female gender, previous stroke or TIA and vascular disease. These risk factors were identified through several studies conducted on the Euro Heart Survey database, a registry of patients in Europe seen by a cardiologist for AF over a 12 month period between 2003 and 2004 (2). The initial validation study on the same cohort (n=1,084) did show an increase in thromboembolism incidence with increasing scores and better prediction of low risk patients compared to the original CHADS2 (2).

In terms of further validation, a prospective Swedish cohort study consisting of 182,678 subjects with a diagnosis of AF as identified by the Swedish National Hospital Discharge Registry examined both thromboembolism and risk of bleeding (3).Patients were excluded if they had valvular AF due to mitral stenosis, had undergone valvular surgery, or died in conjunction with the index-generating hospital contact (3). Risk factors identified with a hazard ratio >1 include age, prior ischemic stroke, hypertension, diabetes, female gender, vascular disease, and prior ICH (3). Of note, heart failure was not defined as an independent risk factor in this study, although a prior prospective study of 1066 patients from 3 clinical trials did show systolic impairment as a risk factor for stroke and thromboembolism (4).

This study has the advantage of a large patient population selected by minimizing bias using ICD-10 criteria from the patient registry, with explicit and objective endpoints being assessed. However, it is limited to previously hospitalized patients and may not be applicable for patients with less severe disease. There is no mention of blinding of outcome assessment in this study.

Several other studies have been conducted on the validation of the CHA2DS2-VASc score including in the outpatient setting with 2600 patients followed at 7 anticoagulation clinics and in an anticoagulated AF clinical trial cohort (5, 6). A registry based cohort study by Olesen et. al that directly compared the CHADS2 to the CHADS2DS2-VASc score in categorizing patients as low or high risk, showed a better C-statistic over 10 years with the newer CHA2DS2-VASc criteria (0.888 vs 0.812) (7).

However, it is worth noting that there is substantial heterogeneity in terms of what point score defines a truly low risk score (8). In recent years, there has been debate over whether or not anticoagulation should be offered to patients with only one risk factor. A systematic review and meta-analysis conducted in 2016 on studies externally validating CHA2DS2-VASc in AF patients not receiving anticoagulants showed significant heterogeneity in stroke risks with wide 95% PIs for scores of 0, 1, and 2 (8). This is reflected by the literature expressing controversy over at which point score to anticoagulate a patient. The ESC guidelines also do not suggest using this criteria on patients with renal failure due to the complexity of their bleeding risk factors (1). Finally, other independent risk factors have been studied including ethnic differences. A retrospective cohort study on 24,612 hospitalized patients with newly diagnosed AF in Taiwan showed increased risk of stroke in younger patients (<65) with AF who would not otherwise be recommended for thromboembolism according to the CHA2DS2-VASc score (9).

In terms of impact, a study on guideline adherence in 64 GPs with 1743 patients in Denmark showed 53.4% concordance with CHA2DS2-VASc guidelines, compared to 64.1% adherence to guidelines according to the CHADS2 score (10). There have been no similar studies conducted in Canada.

Based on the fact that this clinical tool has been studied in multiple large prospective studies with different populations, we have ranked it as a CDR level 2. However, there appears to be significant heterogeneity in selection of scoring systems. As well, there are no impact analysis showing increased uptake by physicians compared to older guidelines, impeding it from being ranked as level 1.

In our video, we define higher risk as >=1 in accordance with the Thrombosis Canada recommendations (11). We also advocate for the concordant use of bleeding risk assessment and independent clinical judgement. We cite the HAS-BLED score as an example, although the HEMORR2HAGES and the ATRIA score have similarly been validated in this population. We also use the 2 CHADs (Mr. and Mrs. Chad) as a memory aid in remembering the CHA2DS2-VASc criteria.

1. Camm, A. J., Lip, G. Y., De Caterina, R., Savelieva, I., Atar, D. & Bax, J. J. (2012). 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 Developed with the special contribution of the European Heart Rhythm Association. European heart journal, 33(21), 2719-2747.

2. Lip, G. Y., Nieuwlaat, R., Pisters, R., Lane, D. A., & Crijns, H. J. (2010). 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, 137(2), 263-272. doi:10.1378/chest.09-1584

3. Friberg, L., Rosenqvist, M., & Lip, G. Y. (2012). Evaluation of risk stratification schemes for ischaemic stroke and bleeding in 182 678 patients with atrial fibrillation: the Swedish Atrial Fibrillation cohort study. European heart journal, 33(12), 1500-1510.

4. Atrial Fibrillation Investigators. (1998). Echocardiographic predictors of stroke in patients with atrial fibrillation: a prospective study of 1,066 patients from 3 clinical trials. Arch Intern Med, 158, 1316-1320.

5. Barnes, G. D., Gu, X., Haymart, B., Kline-Rogers, E., Almany, S., Kozlowski, J., ... & Kaatz, S. (2014). The predictive ability of the CHADS2 and CHA2DS2-VASc scores for bleeding risk in atrial fibrillation: The MAQI2 experience. Thrombosis research, 134(2), 294-299.

6. Jover, E., Roldán, V., Gallego, P., Hernández-Romero, D., Valdés, M., Vicente, V., ... & Marín, F. (2012). Predictive value of the CHA2DS2-VASc score in atrial fibrillation patients at high risk for stroke despite oral anticoagulation. Revista Española de Cardiología (English Edition), 65(7), 627-633.

7. Olesen, J. B., Lip, G. Y., Hansen, M. L., Hansen, P. R., Tolstrup, J. S., Lindhardsen, J & Torp-Pedersen, C. (2011). Validation of risk stratification schemes for predicting stroke and thromboembolism in patients with atrial fibrillation: nationwide cohort study. BMJ, 342.

8. Van Doorn, S., Debray, T. P., Kaasenbrood, F., Hoes, A. W., Rutten, F. H., Moons, K. G., & Geersing, G. J. (2017). Predictive performance of the CHA 2 DS 2‐VAS c rule in atrial fibrillation: a systematic review and meta‐analysis. Journal of Thrombosis and Haemostasis, 15(6), 1065-1077.

9. Chao, T. F., Lip, G. Y., Liu, C. J., Tuan, T. C., Chen, S. J., Wang, K. L., ... & Chen, T. J. (2016). Validation of a modified CHA2DS2-VASc score for stroke risk stratification in Asian patients with atrial fibrillation: a nationwide cohort study. Stroke, 47(10), 2462-2469.

10. Brandes, A., Overgaard, M., Plauborg, L., Dehlendorff, C., Lyck, F., Peulicke, J., ... & Husted, S. (2013). Guideline adherence of antithrombotic treatment initiated by general practitioners in patients with nonvalvular atrial fibrillation: a Danish survey. Clinical cardiology, 36(7), 427-432.

11. Stroke prevention in Atrial Fibrillation. Thrombosis Canada. https://thrombosiscanada.ca/clinicalguides/#