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The Figure shows the conclusions of a recent study from Denmark featuring a direct comparison of the CHADS2 and CHA2DS2-VASc scoring systems, using a nationwide registry of patients admitted to the hospital with AFib who were not anticoagulated. [48] The registry totaled almost 75,000 patients and represents the largest real world cohort ever investigated.
The main outcome measured was stroke and systemic embolism. In patients with a score of 0 by either score, the event rate per 100 patient-years was 1.67 with CHADS2 versus 0.78 with CHA2DS2-VASc. In patients with a score of 1, the event rate per 100 patient-years was 4.75 with CHADS2 and 2.01 with CHA2DS2-VASc.
The important point to remember is that for a female age 66 with an MI, the score will be 3 according to CHA2DS2-VASc and 0 in CHADS2. This illustrates why the lower scores in CHA2DS2-VASc are associated with a better accuracy of low risk – because more patients who are classified as low-to- intermediate risk by CHADS2 are actually at risk, whereas their risk is more accurately classified by CHA2DS2-VASc.
Reiffel JA. Am J Med 2013; 126: 00-00.
[48] Olesen JB, Lip GY, Hansen ML, et al. Validation of risk stratification schemes for predicting stroke and thromboembolism in patients with atrial fibrillation: nationwide cohort study. BMJ. 2011;342:d124. doi: 10.1136/bmj.d124.