Value of Stroke Risk Scores for Recurrent Stroke
What is the predictive ability of two stroke risk scores (CHA2DS2-VASc and Essen Stroke Risk Score) for recurrent stroke in patients without atrial fibrillation?
Using a nationwide registry, patients with incident ischemic stroke and no history of atrial fibrillation were identified. Patients were stratified by the CHA2DS2-VASc and Essen Stroke Risk scores and then followed until stroke recurrence or death. Kaplan-Meier and Cox proportional hazards models were developed to estimate incidence rates, hazard ratios, and cumulative risks.
The registry identified 42,182 patients with incidence ischemic stroke and no atrial fibrillation. One-year incidence of recurrent stroke, death, or cardiovascular events was 3.6%, 10.5%, and 6.7%, respectively. The incidence rates, hazard ratios, and cumulative risk of all outcomes increased with increasing risk scores. Both risk scores had modest predictive ability for 1-year recurrent stroke (0.52 for CHA2DS2-VASc and 0.54 for Essen Stroke Risk Score) and cardiovascular events (0.53 for CHA2DS2-VASc and 0.55 for Essen Stroke Risk Score), but better predictive ability for 1-year death (0.68 for CHA2DS2-VASc and 0.65 for Essen Stroke Risk Score).
The authors concluded that increasing CHA2DS2-VASc and Essen Stroke Risk scores are associated with increasing risk of recurrent stroke, death, and cardiovascular events. However, the authors also note that the discriminatory performance of these two scores was modest, questioning their clinical role.
This study highlights the risk of recurrent stroke, cardiovascular events, and death in a population of ischemic stroke patients without known atrial fibrillation. While it is not surprising that patients with more comorbid illness experience higher rates of all three events, the clinical utility of the CHA2DS2-VASc and Essen Stroke Risk Score is limited. However, most studies have noted the predictive ability of the CHA2DS2-VASc for stroke in atrial fibrillation patients to be modest as well (C-statistics 0.61 in the derivation cohort [Lip GY, et al., Chest 2010;137:263-72] and 0.69 in at least one validation study [Larsen TB, et al., Circ Cardiovasc Qual Outcomes 2012;5:335-42]). Clinicians should remember the inherent limitations of any risk prediction model when counseling individual patients about prognosis or treatment choices.
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