Abstract 80: Application of the ABCD2 Score to Assess the Risk of Stroke in Dizzy Patients Presenting to 19 Emergency Departments
Background: Dizziness is a very common Emergency Department (ED) complaint and can be a harbinger of stroke, yet there is no consensus on how to reliably and efficiently assess this risk. The ABCD2 score was originally developed to predict the short-term risk of stroke after transient ischemic attack and has showed promise when applied to dizzy patients presenting to a single tertiary care center ED. We sought to further validate the performance of the ABCD2 score by applying it across dizzy patients presenting to multiple community-based EDs.
Methods: We conducted a nested-case control study within a cohort of all adults who presented to 19 EDs of a large Northern California integrated health program with a primary triage complaint of dizziness over a one-year period. Cases were defined as patients with an ischemic or hemorrhagic stroke at presentation or within 7 days and were identified using systematic search of electronic health records and medical record review by a vascular neurologist. An equal number of controls were randomly selected from among the remaining dizzy patients without stroke. Components of the ABCD2 score (age, blood pressure, clinical features, and diabetes) were collected from medical records by a trained medical record abstractor masked to the study outcomes. As in a prior study, since the duration of symptoms was not readily available, all patients were assumed to have had symptoms for greater than one hour. We calculated descriptive statistics, compared scores among cases and controls using the Wilcoxon rank-sum test, and assessed the discrimination performance of the ABCD2 score for stroke using ROC curves and the c-statistic. We used the sampling fraction to extrapolate these results to the cohort at large.
Results: In a cohort of 9,566 ED patients with dizziness, 147 (1.54%) had a stroke. The mean ABCD2 score was 4.72 (SD 1.2) in cases and 3.66 (SD 1.1) in controls (p<0.001). The c-statistic for the ABCD2 score as a predictor of stroke was 0.73 (95% CI 0.67-0.79)_slightly lower than the previously reported experience from a single academic center ED of 0.79 (95% CI 0.73-0.85). Extrapolating these data to the entire cohort, those with the lowest score had a predicted risk of stroke of less than one in 500 (0.17%) whereas those with the highest score had a risk of stroke of 11.0%.
Conclusion: The ABCD2 score holds promise as a way to stratify the risk of stroke in ED patients with dizziness when applied across multiple EDs and identifies low-risk group where neuroimaging may not be warranted. However, formal evaluation of other clinical predictors and prospective validation is required before applying this score at the bedside to better target neuroimaging studies to the most appropriate patients without adversely impacting outcomes.
- © 2012 by American Heart Association, Inc.