Comparison Study of ASCO and TOAST Classification System in Chinese Minor Stroke Patients

Abstract

Background: Precise subtype classification based on underlying pathophysiology is important to prevent recurrent attack in minor stroke patients. A newly developed Atherosclerosis, Small vessel disease, Cardiac source, Others (ASCO) phenotypic classification system aims to characterize patients using different grades of evidence for stroke subtypes. However, this system has not been specifically applied to minor stroke population. In our study, the impact of using the newer ASCO criteria on minor stroke etiologies was investigated, and compared with that of Trial of ORG 10172 in Acute Stroke Treatment (TOAST) classification.

Methods: Consecutive patients with minor ischemic stroke (NIHSS ≤3) were assessed and subtyped by the ASCO and TOAST systems. Stroke etiologies were presented and compared. The McNemar test and k statistic were used to analyze the difference and concordance between the 2 algorithms, respectively.

Results: A total of 604 first-ever minor stroke patients were analyzed in the present study. Using TOAST classification, large artery atherosclerosis was the most frequent subtype (281, 46.5%), followed by small artery occlusion category (165, 27.3%). When ASCO was applied, 37 different profiles of stroke etiologies were identified. Using grade 1 of evidence, atherosclerosis (A1) was the most frequent subtype (308, 51.0%), followed by small vessel disease (S1, 178, 29.5%). Under consideration of grades 1 and 2, 239 (39.6%) patients were classified into more than 1 category. The ASCO system revealed determined etiologies in 104 of the 137 patients classified to cause undetermined subtype by TOAST classification. Good to very good accordance was observed between ASCO grade 1 and TOAST schemes across etiologic subtypes (κ = 0.719-0.832) except cause undetermined category (κ = 0.470).

Conclusion: Application of ASCO decreased the proportion of patients assigned to cause undermined category compared to TOAST system. Comprehensive characteristics of ASCO system might be helpful in the personalized therapy or secondary prevention for individual patients in the future.

Keywords: ASCO; Etiology; Minor stroke; TOAST.