Usefulness of CHADS-VASc Score to Predict Stroke Risk Independent of Atrial Fibrillation.

The CHADS-VASc score is used to predict stroke risk among patients with atrial fibrillation (AF). We examined whether a CHADS-VASc score predicts stroke risk among individuals without hospital-diagnosed AF and quantified the magnitude of the association in comparison to AF patients. We used data from population-based medical registries (1995 to 2005) covering all Danish hospitals to identify patients diagnosed with AF (n = 122,980). We matched ≤5 non-AF individuals (n = 612,723) to each AF patient on the individual risk factors included in the CHADS-VASc score. We calculated 10-year absolute risk of ischemic and all-cause stroke in AF and non-AF individuals and compared the stroke risk between cohorts within strata of CHADS-VASc scores using Cox regression. The 10-year risk of ischemic/all-cause stroke was 4.4%/8.8% among non-AF individuals and 6.2%/12% in AF patients, corresponding to a risk difference of 1.8% for ischemic stroke and 3.3% for all-cause stroke. In both cohorts, the stroke risk correlated with increasing CHADS-VASc scores. However, in individuals with CHADS-VASc scores ≥5 who were <75 years or male, the absolute risk of ischemic stroke in individuals without AF exceeded the risk in AF patients. In the same subgroups, the hazard ratio approached unity. Similar results were observed for all-cause stroke. The CHADS-VASc score was associated with 10-year stroke risk also among individuals without hospital-diagnosed AF. In conclusion, primary prophylactic anticoagulation therapy may be relevant in male and younger non-AF individuals with CHADS-VASc scores ≥5. These findings should be confirmed in clinical trials.