Abstract 71: Refining the CT Angiography Collaterals Scoring System to Better Predict Outcome in Acute Ischemic Stroke

Abstract

Background: Collateral circulation profile is an important determinant of outcome in patients with large artery occlusion (LAO). We sought to refine the collateral score (CS) to better identify patients with potential for good outcome after AIS. Methods: We studied 342 patients presenting to our center with AIS and LAO (MCA or ICA) from 03/05 to 04/13. We modified the CS to a 5 point scale (mCS) (fig 1). We dichotomized the score into unfavorable (0-2A) and favorable (2B-3) profiles. Logistic regression model with good and poor discharge outcome (mRS 0-2 and 4-6, respectively) was used. We performed receiver-operating characteristic (ROC) analysis to compare the mCS with the CS and with ASPECTS. Results: Table 1 shows the baseline characteristics. Patients with favorable mCS had a significantly higher odds of a good outcome (OR 9.61, 95%CI 2.78-33.2, p=0.0003). Moreover, patients with unfavorable profile mCS (0-2A) had greater odds of poor outcome at discharge (4-6), and this association was maintained when using more stringent criteria for poor outcome (mRS 5-6) (table 2). These results persisted after adjustment for CT early ischemic changes (ASPECTS) and stroke severity (NIHSS). The modified scale was more precise than the original CS in predicting patients’ clinical outcomes (table 2). Importantly, patients treated with IV tPA who had good collaterals showed better odds of good outcome (OR 7.07, 95%CI 1.39-35.9, p=0.02). Furthermore, mCS showed more specificity and sensitivity than the original CS and ASPECTS as illustrated on ROCs (AUC: 0.73 compared to CS 0.669 and ASPECTS 0.667) in fig 2. Conclusion: The modified collateral CTA score (mCS) which gives a finer gradation of the collaterals discriminates better those who have potential for good outcome compared with the CS and ASPECTS. A simple score that does not require sophisticated radiology expertise may help physicians triage patients in the acute setting by identifying patients who may achieve a good outcome.