Reliability and Utility of the Alberta Stroke Program Early Computed Tomography Score in Hyperacute Stroke

Area of Science:

• Neurology
• Radiology
• Stroke Medicine

Background:

• The Alberta Stroke Program Early Computed Tomography Score (ASPECTS) assesses early ischemic changes on non-contrast computed tomography (NCCT).
• ASPECTS's accuracy depends on the visibility of these changes, which can vary with time since stroke onset.

Purpose of the Study:

• To investigate how the time from ischemic stroke onset to initial NCCT impacts the inter-rater variability of ASPECTS.
• To evaluate the influence of this time window on the prognostic accuracy of ASPECTS for 3-month functional outcomes.

Main Methods:

• Retrospective analysis of ischemic stroke patients treated with IV-tPA (2007-2014).
• Two independent raters assessed ASPECTS, with agreement measured by weighted kappa.
• Onset-to-CT time was dichotomized (≤100 and >100 minutes).
• Prognostic utility assessed using logistic regression and ROC analysis.

Main Results:

• Lower inter-rater agreement for ASPECTS was observed in the early time period (kappa = .75 vs .92, P < .001).
• Significant differences in absolute inter-rater ASPECTS differences were found between early and later time periods (P = .03).
• A trend towards reduced prognostic accuracy was noted in earlier time periods (AUC ≤100 min = .57 vs >100 min = .66, P = .055).

Conclusions:

• ASPECTS demonstrates significantly lower inter-rater agreement in early time windows after ischemic stroke.
• There is a trend towards reduced prognostic accuracy of ASPECTS for functional outcomes when assessed earlier.
• The reliability of ASPECTS for selecting patients for revascularization in early time windows may be questionable.