CHA2DS2-VASc Score Gives Best Prediction of Stroke Risk in AF

April 27, 2012

April 26, 2012 (Hellerup, Denmark) — Another study has suggested that the newer CHA2DS2-VASc score may be more suitable than the CHADS2 score for assessing risk of stroke and thromboembolic events in AF patients, particularly in those at lower risk [1].

Lead author Dr Jonas Bjerring Olesen (Copenhagen University Hospital Gentofte, Hellerup, Denmark) explained that while there is no doubt that high-risk AF patents require anticoagulation, there is a conflict over the definition of low-risk patients who do not require anticoagulation in guidelines from different countries. The US guidelines classify low risk as a score of 0 on the CHADS2 scale, while the European guidelines have adopted the newer CHA2DS2-VASc score, which further subdivides the CHADS2 0 score into several risk categories.

Olesen noted that a CHADS2 score of 0 included CHA2DS2-VASc scores of 0 to 3 and that a CHADS2 score of 1 included CHA2DS2-VASc scores of 1 to 4.

To look further at whether use of the CHA2DS2-VASc score improved risk stratification of AF patients with a CHADS2 score of 0 to 1, Olesen and colleagues used Danish national registries to identify 47 576 AF patients with a CHADS2 score of 0 to 1 and not with treated anticoagulants or heparin. Patients were classified by both CHADS2 and CHA2DS2-VASc risk scores, and the actual rates of stroke/thromboembolism were determined, also from national databases.

Results, published online April 3, 2012 in Thrombosis and Haemostasis, showed that the CHA2DS2-VASc score gave a much more accurate prediction of risks than the CHADS2 score, with risk increasing with each point on the CHA2DS2-VASc scale.

CHA2DS2-VASc scale Stroke/thromboembolism rates at 1-y follow-up
0 0.84
1 1.79
2 3.67
3 5.75
4 8.18

Of particular note, the lowest-risk patients on the CHADS2 scale, with a score of 0, were not all actually low risk, with one-year event rates ranging from 0.84 (CHA2DS2-VASc score=0) to 3.2 (CHA2DS2-VASc score=3).

Olesen commented: "The current data suggest that many of these so-called low-risk patients are actually at substantial risk of events and therefore should be treated with anticoagulants."

He notes that it is only those patients with a CHA2DS2-VASc score of 0 who are actually low risk and do not require anticoagulation. "The present analysis, which represents the largest real-world cohort study of non–warfarin-treated AF patients with a CHADS2 score of 0 to 1, is consistent with the increasing literature from multiple different cohorts that the CHA2DS2-VASc score is better than the CHADS2 score in identifying truly low-risk patients who do not need any antithrombotic therapy."

Olesen further pointed out the need for doctors to rethink the risk assessment of AF patients and, instead of looking for higher-risk patients who need anticoagulation, identify those at lowest risk, who do not need anticoagulation, and treat everyone else. "The availability of the new oral anticoagulants will help in this regard, as they are so much easier to use," he added.

Coauthor Dr Gregory Lip (City Hospital, Birmingham, UK) said the results also had implications for the quality indicators used in the UK as payment incentives for family practitioners. He explained that the current requirement for the payment was to reach a certain proportion of AF patients who had been risk-stratified with the CHADS2 score and had a CHADS2 score of 2 or more and were on anticoagulation. "This implies that patients with a CHADS2 score of 0 to 1 do not need treatment, but this is clearly not the case. Evidence is now in that even patients with a CHADS2 score of 0 can be at substantial risk. The European guidelines recognize this, and the quality indicators need to be updated to reflect this, too."


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