Comparison of the Chinese ischemic stroke subclassification and Trial of Org 10172 in acute stroke treatment systems in minor stroke

Tan et al. BMC Neurology (2016) 16:162 DOI 10.1186/s12883-016-0688-y RESEARCH ARTICLE Open Access Comparison of the Chinese ischemic stroke subclassification and Trial of Org 10172 in acute stroke treatment systems in minor stroke Sha Tan1†, Lei Zhang2†, Xiaoyu Chen3†, Yanqiang Wang4, Yinyao Lin1, Wei Cai1, Yilong Shan1, Wei Qiu1, Xueqiang Hu1 and Zhengqi Lu1* Abstract Background: The underlying causes of minor stroke are difficult to assess. Here, we evaluate the reliability of the Chinese Ischemic Stroke Subclassification (CISS) system in patients with minor stroke, and compare it to the Trial of Org 10172 in Acute Stroke Treatment (TOAST) system. Methods: A total of 320 patients with minor stroke were retrospectively registered and categorized into different subgroups of the CISS and TOAST by two neurologists. Inter- and intra-rater agreement with the two systems were assessed with kappa statistics. Results: The percentage of undetermined etiology (UE) cases in the CISS system was 77.3 % less than that in the TOAST system, which was statistically significant (P < 0.001). The percentage of large artery atherosclerosis (LAA) in the CISS system was 79.7 % more than that in the TOAST system, which was also statistically significant (P < 0.001). The kappa values for inter-examiner agreement were 0.898 (P = 0.031) and 0.732 (P = 0.022) for the CISS and TOAST systems, respectively. The intra-observer reliability indexes were moderate (0.569 for neurologist A, and 0.487 for neurologist B). Conclusions: The CISS and TOAST systems are both reliable in classifying patients with minor stroke. CISS classified more patients into known etiologic categories without sacrificing reliability. Keywords: Minor stroke, Diffusion weight imaging, Chinese Ischemic Stroke Subclassification, Trial of Org 10172 in Acute Stroke Treatment, Implications for treatment Abbreviation: A-A, Artery-to-artery; CE, Cardioembolism; CISS, Chinese ischemic stroke subclassification; CS, Cardiogenic stroke; CTA, Computed tomography angiography; DWI, Diffusion weight imaging; ECG, Echocardiography; END, Early neurological deterioration; HR-MRI, High-resolution brain magnetic resonance imaging; ICAS, Intracranial atherosclerosis; LAA, Large artery atherosclerosis; MES, Microembolic signals; MRA, Magnetic resonance angiography; NIHSS, National institutes of health stroke scale; OE, Other etiologies; PA, Penetrating artery; PAD, Penetrating artery disease; PFO, Patent foramen ovale; SAO, Small artery occlusion; SOE, Stroke of other determined etiologies; SUE, Stroke of undetermined etiology; TCD, Transcranial doppler; TEE, Transesophageal echocardiography; TIA, Transient ischemic attack; TOAST, Trial of Org 10172 in Acute Stroke Treatment; UE, Undetermined etiology * Correspondence: † Equal contributors 1 Department of Neurology, The Third Affiliated Hospital of Sun Yat-sen University, No 600 Tianhe Road, Guangzhou City, Guangdong, China Full list of author information is available at the end of the article © 2016 The Author(s). Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. Tan et al. BMC Neurology (2016) 16:162 Background Ischemic stroke is a major cause of worldwide neurological morbidity and mortality. Identifying the cause of ischemic stroke is of great value for therapeutic choice and prognostic evaluation [1–4]. The Trial of Org 10172 in Acute Stroke Treatment (TOAST) system is the most widely used classification system [5], but it is of limited utility in cases of “stroke of undetermined etiology (SUE)” and has modest inter-examiner reliability [6]. To overcome these issues, modifications to the original TOAST system have been made. For example, a Korean group proposed a new classification system for brain infarctions in 2007, which enriched the definitions of subtypes of ischemic stroke and proved to have higher reliability than the previous system [7]. The Chinese Ischemic Stroke Subclassification (CISS) system was proposed by Gao et al. in 2011 [8]. Compared with TOAST, CISS removed small artery occlusions (SAO), proposed penetrating artery disease, and further classified the underlying mechanisms of large artery atherosclerosis. These changes would be beneficial for the classification of minor stroke which is receiving increased attention in China. However, the reliability of the CISS categorization system has not been assessed. This study aimed to evaluate the reliability of the CISS in patients with minor stroke and to compare the performance of the CISS and TOAST systems in these patients. Methods Ethics statement This research was approved by the ethics committee of the Third Affiliated Hospital of Sun Yat-sen University and conforms to the relevant regulatory standards. All participants involved in this study provided written informed consent. Patients The cohort was recruited retrospectively from the Department of Neurology of The Third Affiliated Hospital of Sun Yat-Sen University. In total, we screened 3205 consecutive patients with ischemic stroke admitted to our hospital between January 2008 and August 2013. Of these, 320 patients fulfilled the inclusion criteria: (a) onset age ≥18 years, (b) onset time ≤7 days, (c) lesions on diffusion weight imaging (DWI), and (d) National Institutes of Health Stroke Scale (NIHSS) score ≤3 on admission. The inclusion procedure is presented in Fig. 1. All patients underwent echocardiography (ECG) or 24 h ECG (94.4 %), high-resolution brain magnetic resonance imaging (HR-MRI), intracranial magnetic resonance angiography (MRA), DWI, and extra-cranial vascular imaging. Risk factors for stroke were also assessed, including gender, hypertension, diabetes, current cigarette smoking, Page 2 of 8 Fig. 1 Patients inclusion chart. DWI: Diffusion weight imaging; NIHSS, National Institutes of Health Stroke Scale coronary heart disease, previous transient ischemic attack (TIA) or stroke, and peripheral arterial disease. The subtype classification Patients were classified into five etiologic/pathophysiological categories according to the TOAST system: large artery atherosclerosis (LAA), cardioembolism (CE), SAO, stroke of other determined etiologies (SOE), and SUE. To be diagnosed as LAA, patients should have paraclinical brain imaging findings of either significant (>50 %) stenosis or occlusion of large arteries, such as the internal carotid artery, middle cerebral artery, vertebral artery, and basilar artery, or their major (...truncated)