Table 3. TOAST and ASCOD/ASCO Stroke Etiology Classification Studies Conducted Internationally.

TOAST: Trial of Org 10172 in Acute Stroke Treatment; CE: cardioembolism; LAA: large artery atherosclerosis; SVO: small vessel occlusion; ASCOD: atherothrombosis (A), small vessel disease (S), cardiac pathology (C), other causes (O), and dissection (D).

Author Name and Year of the Study	Study Population	Observation
Gökçal et al. 2017 [13]	151 patients	Using the TOAST classification, patient stroke etiology was classified into undetermined (41.1%), CE (19.2%), LAA (13.2%), SVO (11.3%), and other causes (15.2%). Compared to the TOAST classification, ASCO classification assigned fewer patients to undetermined etiology subtype (26.5%, p<0.001) and SVO category (21.9%, p<0.001). ASCO also assigned more patients to the LAA group (16.6%).
Arsava et al. 2017 [14]	1,816 patients	The classification systems were different in their ability to assign stroke etiologies to known subtypes; the size of the undetermined category was 53% per the TOAST classification and 42% per the ASCO classification (p < 0.001 for all binary comparisons).
Markaki et al. 2013 [15]	101 patients, 84 with ischemic stroke and 17 with a TIA	There was a moderately high agreement between the TOAST and ASCO classifications in all subtypes. Along with the classification, the one- and four-year mortality rates were observed during a mean observation period of 28 months, during which 26 patients died. The one- and four-year mortality rates, respectively, were 0% and 4% in LAA, 23% and 36% in CE, 0% in SVO, 63% and 100% in unknown etiology, and 12% and 29% in the cryptogenic subtype. For the ASCO classification, the one-year and four-year mortality rates, respectively, were 0% and 6% in LAA, 25% and 36% in CE, 0% in SVO, 0% and 14% in LAA + CE, 16% and 36% in SVO + CE, and 56% and 100% in the undetermined etiology despite complete workup.
Shang et al. 2012 [16]	425 patients with first time ischemic stroke	There was a moderately high agreement between the TOAST and ASCO classification in all subtypes except the “undetermined” etiology subtype (16.2% vs. 15.5 %, p = 0.795).
Wolf et al. 2012 [17]	103 patients	There was a high agreement between the ASCO and TOAST classifications. With ASCO, grades 1-3 were identified in 60.19% A, 75.73% S, 49.51% C, and 3.88% O. Around 68.93% of the patients were classified in more than one category, and only 3.88% remained completely undetermined. With the TOAST classification, the distribution was 9.71% in A, 23.30% in S, 34.95% in C, 1.94% in O, and 30.10% in the undetermined subtype.