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Interrater reliability of an etiologic classification of ischemic stroke
C J Johnson1, S J Kittner, R J McCarter
1Department of Neurology, Johns Hopkins Bayview, Baltimore, MD 21224.
Insights
Developing an etiology-specific ischemic stroke classification improves accuracy for research. This system demonstrated fair to good reliability, aiding epidemiological and pathophysiological studies of stroke causes.
Area of Science:
- Neurology
- Epidemiology
- Medical Informatics
Background:
- Accurate stroke cause identification is vital for research and clinical practice.
- Existing ischemic stroke classifications show significant variability.
- An etiology-specific classification system was developed to address this need.
Purpose of the Study:
- To develop and implement an etiology-specific classification for ischemic stroke.
- To evaluate the interrater reliability of this new classification system.
Main Methods:
- Reviewed 160 ischemic stroke cases in young adults.
- Paired neurologists assigned cases to prioritized etiological categories.
- Interrater agreement was assessed using kappa statistics.
Main Results:
- Kappa values indicated fair to good reliability for most stroke causes.
- Lacunar stroke showed the greatest pair-to-pair variation (kappa = 0.31).
- Strokes of undetermined or hematologic cause had borderline fair reliability.
Conclusions:
- The utility of a stroke classification depends on its application.
- An etiologic classification is valuable for stroke epidemiology and pathophysiology research.
- Explicit criteria can achieve fair to good reliability for stroke etiology classification.
Background And Purpose:
Precise identification of the cause of stroke is critical to research and clinical practice. Published series of ischemic stroke show considerable variation in the proportion of cases classified as atherosclerotic large-vessel disease, lacunar infarct, cardioembolic stroke, stroke of other known cause, and stroke of undetermined etiology. We describe the development and use of an etiology-specific classification of ischemic stroke. The interrater reliability of the classification is then evaluated.
Methods:
A total of 160 cases of ischemic strokes in young adults were reviewed by paired neurologists who assigned cases to prioritized categories. The results of paired ratings were evaluated for each of the potential causes. Interrater agreement was assessed by means of kappa, which is the chance-adjusted percent agreement.
Results:
For standard pairs, kappa was fair to good for all causes except lacunar stroke (kappa = 0.31); however, pair-to-pair variation was greatest for lacunar strokes. Strokes of undetermined cause and hematologic/other cause were of borderline fair reliability.
Conclusions:
The utility of a stroke classification system is dependent on its intended use. An etiologic classification is useful in studies of the epidemiology and pathophysiological basis of stroke. Fair to good reliability for an etiologic classification of stroke can be obtained when criteria are explicit.