The ASPIRE approach for TIA risk stratification

The risk of stroke after transient ischemic attack (TIA) is elevated in the days to weeks after TIA. A variety of prediction rules to predict stroke risk have been suggested. In Alberta a triage algorithm to facilitate urgent access based on risk level was agreed upon for the province. Patients with ABCD2 score ≥ 4, or motor or speech symptoms lasting greater than five minutes, or with atrial fibrillation were considered high risk (the ASPIRE approach). We assessed the ability of the ASPIRE approach to identify patients at risk for stroke.

We retrospectively reviewed charts from 573 consecutive patients diagnosed with TIA in Foothills Hospital emergency room from 2002 through 2005. We recorded clinical and event details and identified the risk of stroke at three months.

Among 573 patients the 90-day risk of stroke was 4.7% (95% CI 3.0%, 6.4%). 78% of the patients were identified as high risk using this approach. In patients defined as high risk on the ASPIRE approach there was a 6.3% (95% CI 4.2%, 8.9%) risk of stroke. In patients defined as low risk using the ASPIRE approach there were no recurrent strokes (100% negative predictive value). In contrast, two patients with low ABCD2 scores (ABCD2 score < 4) suffered recurrent strokes.

The ASPIRE approach has a perfect negative predictive value in the population in predicting stroke. However, this high sensitivity comes at a cost of identifying most patients as high risk.