Value of utilizing both ASPECTS and CT angiography collateral score for outcome prediction in acute ischemic stroke

Background: Alberta Stroke Program Early CT Score (ASPECTS) represents the extent of irreversibly damaged tissue; while CT angiography collateral score (CTA-CS) denotes the degree of collaterals. Aims: We investigated whether there is cumulative value in using both ASPECTS and CTA-CS for outcome prediction and attempted to determine the specific subgroup of patients who could benefit from successful reperfusion using these scores. Methods: This is a retrospective observational study of stroke patients treated with intra-arterial reperfusion therapy for unilateral arterial occlusion in the anterior circulation. A favorable outcome was defined as modified Rankin Scale≤2 at three-months. Receiver operating characteristic comparison analysis was performed to decide whether outcome predictability increases when ASPECTS and CTA-CS are used together. Classification and regression tree (CART) analysis was done to identify the variables that best predict outcome and define the specific subgroup of patients who could benefit from successful reperfusion. Results: A total of 91 consecutive patients were included. Outcome predictability of ASPECTS with CTA-CS was better than that of ASPECTS (P=0·088) or that of CTA-CS (P=0·049). CART analysis revealed that ASPECTS>5 was the primary determinant of favorable outcome, followed by CTA-CS>1. Among 19 patients with ASPECTS≤5, none had a favorable outcome. Successful reperfusion was associated significantly with favorable outcome in the 51 patients with ASPECTS>5 and CTA-CS>1, but not in the 21 patients with ASPECTS>5 and CTA-CS≤1. Conclusions: Outcome predictability improves when using ASPECTS and CTA-CS together.