Association Between Ischemic Stroke Subtype and Stroke Severity: The Atherosclerosis Risk in Communities Study

Area of Science:

• Neurology
• Epidemiology
• Cardiovascular Research

Background:

• Stroke disability varies by ischemic stroke subtype.
• Embolic strokes may be more severe than thrombotic strokes.
• The influence of comorbidities and initial stroke severity on outcomes is unclear.

Purpose of the Study:

• To compare stroke severity and mortality risk between embolic and thrombotic stroke subtypes.
• To investigate if stroke subtype differences are explained by comorbidities or initial severity.
• To examine if race and sex modify the association between stroke subtype and outcomes.

Main Methods:

• Analysis of Atherosclerosis Risk in Communities (ARIC) study participants with ischemic stroke.
• Use of multinomial logistic regression to assess stroke subtype and admission NIH Stroke Scale (NIHSS) severity.
• Application of Cox proportional hazard models to evaluate all-cause mortality, with interaction analysis for race and sex.

Main Results:

• Embolic stroke patients had a higher risk of more severe strokes (NIHSS >5) compared to thrombotic stroke patients.
• This association remained significant after adjusting for atrial fibrillation, though attenuated.
• Stroke severity association with subtype differed by sex, and embolic stroke increased mortality risk (HR 1.66).

Conclusions:

• Embolic stroke is associated with greater initial severity and increased mortality risk compared to thrombotic stroke.
• These differences persist after adjusting for patient-level confounders.
• Sex is a significant modifier of the relationship between stroke subtype and severity.