Antiplatelet therapy plays a critical role in the treatment and prevention of noncardiac ischemic stroke or transient ischemic attack (TIA), and is recommended by guidelines worldwidely [1], [2]. However, even after standard antiplatelet therapy, about 3.8% ∼ 9.7% of patients with ischemic stroke or TIA still experience recurrent stroke within one year [3]. The latest study reveals that the risk of stroke recurrence after the first incident stroke within 5 years in China is as high as 40% [4]. Clopidogrel is a commonly used antiplatelet agent for secondary prevention in ischemic stroke or TIA patients. High platelet reactivity (HPR) on clopidogrel, also known as clopidogrel resistance (CR), was defined as failure to biologically inhibit platelet activation and aggregation after treatment with clopidogrel, and has attracted particular attention as a potential factor related to adverse clinical outcomes including ischemic events and deaths in ischemic stroke or TIA patients [5], [6].

Multiple experimental methods have been used to detect CR, including VerifyNow System, Multiplate, thromboelastography (TEG), Multiplate, light transmission aggregometry, etc. Until now, a sensitive and widely applicable method for CR detection has not yet been determined [7], [8]. The ABCD-GENE score is a novel risk model for CR detection in patients underwent percutaneous coronary intervention (PCI) [9]. It is increasingly being used to identify patients at high-risk of adverse clinical outcomes following PCI [9]. However, for the patients with ischemic stroke or TIA, the diagnostic ability of the ABCD-GENE score for CR and adverse clinical outcomes needs to be identified.

Many previous studies reported the association between CR and adverse clinical outcomes in acute ischemic stroke or TIA patients. In these studies, the observation time generally began within 48 hours of onset or earlier; the follow-up time varied from 10 days to 3 months [10], [11], [12]. However, whether CR affects long-term (after 3 months of onset) [13] clinical prognosis in ischemic stroke or TIA patients is still unclarified. Considering that the risk of adverse clinical outcomes tended to be decreased and stable after 3 months of onset [14], the association between CR and long-term clinical prognosis needs to be investigated. Therefore, the present study was conducted to (1) analyze the diagnostic ability of the ABCD-GENE score for CR in ischemic stroke or TIA patients, and (2) investigate the association between CR and long-term clinical prognosis in patients with ischemic stroke or TIA.