Seasonal Variation in Neurological Severity and Clinical Outcomes in Ischemic Stroke Patients　― A 9-Year Study of 5,238 Patients ―

Abstract

and spring. 7 Another study from Japan found no significant correlation between the 1-year clinical outcomes of ischemic stroke and seasonal changes. 8 In a recent study in Saudi Arabia, Alghamdi et al found that weather or seasonal variations had no effect on stroke incidence or outcomes. 9 However, previous studies have only covered short periods of 2-5 years, so in the present study we studied the relationship of season and patterns of neurological severity and outcomes of acute ischemic stroke in a hospital-based study with 9-year cohort data. The findings of this study can provide evidence for the formulation of effective strategies to deal with the adverse consequences of ischemic stroke. Methods Study PopulationThe study population was patients admitted to the Stroke Unit of the Second Hospital of Tianjin Medical University W orldwide, stroke is a leading cause of mortality and disability, 1 and China has a high prevalence and heavy burden of stroke, with ischemic stroke as the most common type, accounting for up to 70%. 2 In addition to the well-known common risk factors, including hypertension, diabetes mellitus, overweight, atrial fibrillation (AF) and smoking, 3 the relationship between meteorological factors and ischemic stroke has attracted the attention of researchers in recent years. 4 Several epidemiological and experimental studies investigated the strong influence of seasonality on stroke incidence, and most found higher stroke incidence during winter and spring and lower incidence during summer and autumn. 5,6In addition, weather changes may lead to severe stroke or worsen the outcome of stroke, which is a public health problem of concern. However, the results of clinical studies differ, and some are even contradictory. A recent study in the USA demonstrated that worse outcomes of ischemic stroke were more frequent in cold seasons including winter