Objective: To investigate the effects of extreme high and low temperatures on admission risk of acute ischemic stroke (AIS) and its etiology subtypes. Methods: From January 1, 2016 to December 31, 2017, the data of inpatients with AIS from Zhongnan Hospital of Wuhan University and the meteorological data and air pollution data from China Meteorological Data Network in the same period were collected continuously. According to TOAST etiology criteria, the patients were divided into large artery atherosclerosis (LAA), small vessel occlusion (SVO), cardioembolism (CE), and stroke of other etiology (SOE). A time series analysis of the distributed lag model was used to investigate the effects of extreme high and low temperatures on the admission of patients with AIS and its etiology subtype, and air pollution, air pressure, humidity, and wind speed were used as confounding factors to exclude interference. Results: A total of 1 413 patients with AIS were enrolled, including 906 men (64.4%), age 67.7±12.8 years. The thresholds of extreme low temperature (1%, 5% and 10% of the average temperature) were 0.7 ℃, 3.3 ℃, and 4.9 ℃. The thresholds of extreme high temperature (90%, 95% and 99% of the average temperature) were 29.2 ℃, 31.6 ℃, and 32.9 ℃. Extreme high temperature increased the risk of hospitalization in patients with AIS (lag 0 day; relative risk [RR] 1.54, 95% confidence interval [CI] 1.01-2.34). It was mainly related to the increased risk of hospitalization in patients with CE subtype (lag 0 day; RR 7.64, 95% CI 1.19-49.09). There was no significant correlation between the extreme low temperature and the risk of hospitalization of AIS (lag 2 days; RR 0.99, 95% CI 0.71-1.37), but it significantly increased the risk of hospitalization in patients with LAA subtypes (lag 2 days; RR 3.04, 95% CI 1.33-6.95), and it was still statistically significant at lag 3 days (RR 2.87, 95% CI 1.57-5.25) and lag 4 days (RR 2.19, 95% CI 1.15-4.15). Conclusion Extreme high temperature may increase the risk of hospitalization in patients with AIS and CE subtypes, while extreme low temperature may increase the risk of hospitalization in patients with LAA subtypes.

Objective To investigate the effect of short-term environmental ozone (O3) exposure on hospitalization risk of acute ischemic stroke (AIS) and its subtypes.Methods From January 1,2016 to December 31,2017,the hospitalization data of patients with AIS from Zhongnan Hospital of Wuhan University,air pollutant data published by China Air Quality Online Monitoring and Analysis Plafform,and the meteorological data published by China Meteorological Data Network were collectcd.According to TOAST etiological classification criteria,the patients with AIS were divided into large-artery atherosclerosis (LAA),small-artery occlusion (SVO),cardioembolism (CE),and stroke of other etiology (SOE).The effect of short-term O3 exposure on the hospitalization risk of AIS and its subtypes was analyzed retrospectively using a distributed lag non-linear model of time series analysis.Results A total of 1 413 patients with AIS were enrolled,including 910 males (64.4％),aged 67.7± 12.8 years (range,18-99 years).Short-term O3 exposure increased the overall hospitalization risk of AIS [relative risk (RR) 1.06,95％ confidence interval (CI) 0.99-1.13],mainly caused by increased hospitalization risks of LAA (RR 1.17,95％ CI 1.02-1.34;lag 5 d) and SVO (RR 1.24,95％ CI 1.06-1.45;lag 3 d).After introducing double pollutant (O3 + other pollutants) model its RR did not have significant changes.A stratified analysis based on demographic characteristics and vascular risk factors showed that the different populations had different sensitivities to the acute hazard effects of O3.Conclusion Short-term exposure to O3 could significantly increase the hospitalization risks of LAA and SVO.