CHA2DS2-VASc more useful than CHAD2 in predicting stroke risk

Mark Sweeney, University of Cambridge School of Clinical Medicine, Addenbrooke's Hospital, Hills Road, Cambridge, CB2 0SP

Patients with atrial fibrillation have an increased risk of stroke and thromboembolic events and in some patients with other risk factors this risk is high enough to require anticoagulation. The use of scoring systems to stratify the risk of these thromboembolic events has allowed clinicians to categorize patients into low, intermediate and high risk groups. By doing this patients can be targeted with the most effective treatments either vitamin K antagonists, anti-platelet drugs or no treatment.

The parameters used to calculate this risk have caused some controversy and a study published in the BMJ this week compares the most commonly used stratification score, CHAD2 to the newer CHA2DS2-VASc. (1) The parameters used in each are shown in table 1. A score of 2 or more in either of these scoring systems is considered high risk, a score of 1 is intermediate risk and 0 is low risk.

They found that the CHA2DS2-VASc score was significantly better at stratifying the patients into risk groups. Patients who had a CHA2DS2-VASc score of 0 were less likely to have a thromboembolic event than those with a CHAD2 score of 0, therefore more truly low risk and those with a CHA2DS2-VASc score of 1 were also less likely to have a thromboembolic event than those with a CHAD2 score of 1.

While the benefit of the CHAD2 score lies in its simplicity, the extra refinement brought by the CHA2DS2-VASc score helps to better predict the future risk of thromboembolic events and should help to tailor treatment more adequately to the individual patient.

Table
CHAD2 CHA2DS2-VASc
Congestive heart failure Congestive heart failure
Hypertension Hypertension
Age ≥ 75 Age ≥ 75 (Double Point)
Diabetes Mellitus Diabetes Mellitus
Previous stroke/ TIA (double point) Previous stroke/ TIA (double point)
Vascular disease
Age 65-74
Sex (female)
References: 

1. Olesen, J., Lip, G., Hansen, M., Hansen, P., Tolstrup, J., Lindhardsen, J., et al. (2011). Validation of risk stratification schemes for predicting stroke and thromboembolism in patients with atrial fibrillation: nationwide cohort study. BMJ , Jan 31;342:d124.