CHA2DS2-VASc more useful than CHAD2 in predicting stroke risk

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.