Association between Low Ambient Temperature and the Severity of Acute Ischemic Stroke

Objective: To explore the relationships among ambient temperature, ischemic stroke severity, and blood pressure. Methods: Meteorological data (2005–2015) were collected from the Guangzhou Meteorological Data Service. Ischemic stroke patients from the Department of Neurology of the First Affiliated Hospital, Sun Yat-sen University were retrospectively evaluated, each winter from 2005 to 2015. Patient demographics, baseline measurements, and National Institute of Health Stroke Scale (NIHSS) score were evaluated. Results: Three hundred sixty-two patients were included. The median latency from symptom onset to admission was 2 d (IQR: 1–3 d). During recruitment, the highest and lowest temperatures were 39℃ and 1.3℃, respectively. Hypertension was the most common comorbidity (75.1%). NIHSS scores at admission and discharge were higher in the cold-exposed group than in the controls regardless of the average temperature at admission. In addition, systolic and diastolic blood pressure values at admission were higher in the cold-exposed group than in the controls. When stratified by hypertensive status, the average and minimum temperatures at admission were negatively associated with systolic and diastolic blood pressure values in hypertensive patients. Reductions in the average and minimum temperatures at symptom onset were associated with more severe stroke. Conclusion: Ischemic stroke patients with symptom onset in winter had higher systolic blood pressure values and more serious neurologic deficits upon admission.