A History of the TOAST Classification
Adams, HP Jr, Bendixenb BH, Kappelle LJ, Biller J, Love BB, Gordon DL, and Marsh EE, 3rd. Classification of subtype of acute ischemic stroke. Definitions for use in a multicenter clinical trial. TOAST. Trial of Org 10172 in Acute Stroke Treatment. Stroke. 2015
The TOAST Classification system was developed to be able to better classify ischemic strokes that patients had suffered on the basis of etiology as this had an impact on the patient’s prognosis and risk of stroke recurrence. Additionally, the TOAST classification system has been used by different research trials to be able to report the stroke subtype population that their study encountered and by using the same system across different studies, the populations could be better compared with one another.
The article by Drs. Adams and Biller emphasizes the history of the TOAST (or the obviously more convenient name Trial of Org 10172 in Acute Stroke Treatment) classification system, specifically how and why it was developed, and the idea behind which stroke etiologies should be included in the five broad categories (Large artery, small artery, cardioembolic, other, undetermined). An example is how it was intended for large artery strokes to specifically mean strokes related to large artery atherosclerotic disease, and that these patients should usually have evidence of symptomatic atherosclerotic disease elsewhere i.e. coronary or peripheral arteries. They clearly defined that the “other” category included patients that had an established cause of stroke but could not be categorized in the large artery, small artery, or cardioembolic categories, such as non-atherosclerotic vasculopathies, dissections, hypercoagulable states, etc. The reason for inclusion in the “undetermined” group was three-fold as this category included patients for which no etiology was found due to complete but negative workup, incomplete workup, or multifactorial etiologies possible for stroke.
The TOAST scale is easy to use and has good inter-rater agreement and intra-rater reproducibility. The authors recognize the limitations and criticisms of the TOAST scale including how it cannot be applied to pediatric stroke, the plea for dissection-related strokes to be a separate category, and the varying prognosis of different cardioembolic disorders. They also mention how a full workup is always needed for patients to not be put in the undetermined category, so the application of the scale may not be omnipresent. The scale has undergone numerous modifications but the idea has endured the test of time and it is the basis for which new scales are being developed. The TOAST Scale original paper has been cited >4800 times making it one of the most commonly cited contributions to the Stroke journal. The TOAST scale has helped define the thought process that stroke neurologists around the world use when working up a stroke patient and its contribution to our field is invaluable.