Factors for short-term outcomes in patients with a minor stroke: results from China National Stroke Registry

Stroke recurrence and dependency in patients with an initial non-disabling stroke is one of the most depressing medical situations worldwide. Stroke has been the leading cause of death and acquired adult disability in China [1, 2], furthermore, where the incidence rate of ischemic stroke increased by 8.7 % annually on average from 1984 to 2004 [3]. Increasing evidences have suggested that a significant minority of patients with an acute non-disabling stroke become disabled or dead due to recurrent strokes or neurological deterioration within first few hours or days [4‐6]. A population-based study showed that the true risk of recurrent stroke after minor stroke is up to about 18 % at 3 months [7]. As for stroke-related disability, it is relatively common among the patients with mild or rapid improving symptom who were not treated with the intravenous thrombolysis [5, 6, 8, 9].

Considering the variable clinical course in the immediate aftermath of a minor stroke, it will become more important to assess risk factors for detecting patients with a poorer clinical outcome, for whom aggressive prevention treatment like dual or triple antiplatelet is urgently needed. At present, majority of studies have been focusing on the early risk of recurrent stroke after transient ischemic attack (TIA) and a minor stroke [10‐13], but data about the short-term risk of poor functional outcome and subsequent stroke assessed in patients with minor stroke was limited, and even not available in China. Using China National Stroke Registry (CNSR), we aimed to identify factors associated with early stroke recurrence, stroke disability and all-cause death after an initial minor stroke during a 90-day follow-up period.

In the largest sample of Chinese stroke adults to date, the present study found that a significant minority of patients with the minor stroke experienced permanent neurological deficits or death and the recurrent stroke during the 3-month follow-up period. Nevertheless, patients at earlier phase after minor stroke were more likely to have high risk of stroke recurrence and poor functional outcome at 3 months after stroke onset.

Our data showed a 3-month recurrence rate of 9.8 % in patients with a minor stroke. The short-term risk of stroke recurrence was consistent to about 10 % at 3 months after TIA [10, 11], but lower than the range between 14 and 18 % found in two previous studies of patients with a minor stroke [7, 21]. The early risk of sequent stroke is commonly underestimated with the reason that patients were usually enrolled several days after a minor stroke and any patient who had a major stroke before the recruitment was not included. We also detected that hypertension, diabetes mellitus and previous stroke were predictors of early recurrent stroke, as was suggested in previous studies [10, 11]. Atrial fibrillation was independently associated with the risk of early recurrent stroke, which was not confirmed in population from western countries [11, 21]. The possible explanation is that in clinical practice of China, unlike North America and Europe, only 14.3 % stroke patients with atrial fibrillation receive oral anticoagulation in real clinical practice [22]. Of those patients who developed recurrent stroke in our study, 7.5 % patients with atrial fibrillation received anticoagulation, which was lower than the early study. Previous studies had reported that coronary artery disease was strongly associated with stroke [23, 24]. Carotid atherosclerosis and stroke of carotid origin are coronary artery disease risk equivalents [25], thus coronary artery disease and cerebrovascular diseases are highly correlated. Our present study found that coronary artery disease was significantly associated with the risk of stroke recurrence at 3 months after adjusting other risk factors, so coronary artery disease can be regarded as an independent risk factor. The impact of time after a minor stroke for stroke recurrence was also dissected out in multivariate model analysis. It presented that the patients at the earlier phase of minor stroke were more likely to experience subsequent stroke (OR 1.22; 95 % CI, 0.99-1.51; p = 0.06).

The clinical functional outcomes of patients with minor stroke is not invariably benign. The rate of patients with stroke disability at 3 months in this study was up to 14.5 %. The multivariable-adjusted analysis revealed that patients at earlier phase of minor stroke (≤24 h) were about 1.5 times more likely to have a stroke disability at 3 months, and tended to have all-cause death at 3 months. The reason was unknown, but it was reported in a previous study [26] that patients with more severe stroke immediately contacted emergency services after stroke onset to avoid disability and death. Therefore, it’s likely that the time from onset to admission was a proxy for stroke severity even in minor strokes.

The study had some limitations. First, the participating hospitals were selected by convenience in nature. The majority of hospitals selected were tertiary hospitals that may not represent the status quo of stroke in rural and smaller community hospitals. Second, unavoidable delays before the inclusion of patients in the study led to the underestimation of the recurrent stroke risk and poor functional outcomes. The reason was that a portion of patients with minor stroke prior to study enrollment were not categorized into the group of minor stroke due to recurrent stroke or worsening of their presenting events. Third, it would be helpful if the abnormality on the imaging metric could be taken into as part of multivariate analysis for neurological deterioration. However, the detailed information about imaging was unavailable and the analysis couldn’t be performed. Furthermore, as we mainly focus on the impact of risk factors before admission on outcomes, the other potentially significant factors including treatments and therapies variables during hospitalization and at discharge were not included in the analysis.

Our study indicated the short-term risk of early recurrent stroke and poor functional outcome in Chinese patients with a minor stroke was substantial. Therefore, patients with a minor stroke should be given expeditious assessment and urgent aggressive intervention.