Etiologic subtype predicts outcome in mild stroke: prospective data from a hospital stroke registry

Due to this is an observational study that will only assess outcomes in participants, all participants or their designated relatives provided verbal informed consent for obtaining relative prognostic information. This research project was approved by the Scientific Research Department of West China Hospital, which conformed to the local ethic criteria for human researches. We included acute ischemic stroke admitted consecutively to neurological wards of the West China Hospital, Sichuan University within 30 days of symptom onset between September. 01, 2009 to August. 31, 2011. All patients had a clinical diagnosis of stroke according to World Health Organization (WHO) criteria and intracranial hemorrhage were further excluded by CT or MRI scan in the hospital [12]. Patients with National Institute of Health Stroke Scale (NIHSS)≦3 were included [13] in this study.

Details of patient demographies, vascular risk factors, Blood pressure (BP) on admission, laboratory test, brain image data and complications were recorded at the time of assessment using a standardized structured form. Vascular risk factors included hypertension (HTN), diabetes, dyslipidemia, coronary heart disease (CHD), history of stroke, status of smoking and alcohol. Severity of stroke was assessed using the NIHSS score. Medical complications include respiratory infection, urinary tract infection, electrolyte disturbances, hemorrhage of digestive tract and epilepsy. Determination of ischemic stroke etiology was according to the Trial of Org 10172 in Acute Stroke Treatment (TOAST) criteria: large-artery atherosclerosis (LAA); small artery occlusion (SAO); cardioembolism (CE); stroke of other determined cause (OC); and stroke of undetermined cause (UND) [14].

The main outcomes were death and disability at 3 month after onset. Death was all-cause case fatality. Disability was defined as modified Rankin Scale (mRS) > 2 [15]. Patients were followed-up by telephone call, clinic interview or letter inquiry. To ensure the quality of information collection, all investigators received training in the beginning according to our standard operational manual. All data were recorded in a structured data sheet. The outcome assessors were blinded to the information of patients. The poor outcome defined as death or disability (mRS >2) at 3 months.

Differences between two groups were tested using t test, Mann–Whitney U test or Chi-Square test where appropriate. Variables that were identified as significant in the univariate analyses (P <0.10) were entered into multivariate logistic regression analyses. The multivariate logistical regression was used to analyze association between different etiologic subtype and clinical outcomes, adjusting for all potential confounders including age, sex, NIHSS on admission, vascular risk factors and complications et al. Data are reported with Relative Risk (RR) and 95% confidence intervals (CI). All statistical analyses were performed with SPSS for Windows, Version 16.0 (SPSS Inc.).

We included 1655 patients with acute ischemic stroke within 30 days of symptom onset. Of them, patients with mild stroke accounted for 41.1% (680/1655). The mean age was 62.54 ± 13.51 years (18–97 years). Males accounted for 65.4% (445/680). The median time of symptoms onset to admission was 72 hours (2–270 hours). The median of NIHSS on admission is 2(1–3). Of these patients, 21.5% large-artery atherosclerosis, 40.6% small-vessel disease, 7.5% cardioembolisms, 2.2% other causes and 28.2% undetermined causes. 3.8% (26/680) of cases admitted within 3 hours and 4.7% (32/680) admitted within 4.5 hours. However, no patient received rt-PA treatment. The common complications were 7.7% respiratory tract infection, 2.0% urinary tract infection, 2.2% electrolyte imbalances, 0.9% gastrointestinal bleeding and 0.4% secondary epilepsy. The proportion of case fatality and death/disability was 2.2% and 10.1% respectively at 3 months. In order to analyze the effect of specific etiology on prognosis of minor stroke, such as cardioembolisms, large-artery atherosclerosis, small-vessel disease, the patients with undetermined etiology were excluded from the following analysis. In addition, other causes were also excluded due to few patients were included in our study. So we keep a total of 453 cases for further analysis. Compared to patients without death or disability, patients with poor outcome were younger, had higher proportions of large-artery atherosclerosis or cardioembolisms and had high rate of complications of respiratory and urinary tract infection. Baseline characteristics of this cohort were described in Table 1.

After adjustment of potential confounders, such as age, sex, NIHSS on admission and vascular risk factors et al., cardioembolism was the independent predictor of death or disability at 3rdmonth (RR = 3.395;95%CI 1.257 ~ 9.170) (Table 2). Small vessel occlusion also was the independent predictor of good outcome at 3rd month (RR = 0.412;95%CI 0.202 ~ 0.842) (Table 3). Large-artery atherosclerosis was not the independent predictor of death or disability, but had a trend of increasing death/disability (RR = 1.497; 95%CI 0.723 ~ 3.102) (data not shown). In addition, age, history of intracerebral hemorrhage and complications were independent predictive factor for death or disability at 3rd month across different etiologic subtype analysis.