Effects of temperature on ischemic stroke admissions in Beijing residents based on distributed lag non-linear model

Background Ischemic stroke is one of the major public health issues in China. In recent years, the relationship between temperature and ischemic stroke in general population has been widely concerned. However, the current research results are inconsistent.

Objective This study is conducted to explore the influence of daily temperature on ischemic stroke admissions of residents in Beijing and provide scientific basis for relevant departments to establish comprehensive prevention and treatment strategies against ischemic stroke.

Methods Meteorological data, air pollution data, and ischemic stroke admission data from 11 January 2013 to 31 December 2017 in Beijing were collected and described. The correlation between air pollutants and meteorological factors were analyzed by Spearman rank correlation analysis. The association between daily temperature and hospital admissions for ischemic stroke was estimated using distributed lag nonlinear model (DLNM). Three-dimensional graph for ischemic stroke and lag-response curves for different temperatures were plotted. The association stratified by sex or age (< 65 and ≥ 65 years) was also examined.

Results In total, there were 380 127 ischemic stroke admissions in Beijing from 2013 to 2017, the median number of daily admissions was 209 (interquartile range:138-261). A nonlinear relationship was found between daily mean temperature and ischemic stroke admissions, and the effect was lagged. The effect of temperature on admissions of ischemic stroke appeared since day 10, and declined after reaching the peak since day 13. The largest RR at -3℃ was 1.18 (95% CI:1.05-1.32) at lag 0-21 days. The RRs at 1℃ were 1.08 (95% CI:1.02-1.15) at lag 0-14 days and 1.14 (95% CI:1.06-1.24) at lag 0-21 days, respectively. The results of stratified analysis presented that men and visitors less than 65 years of age were more sensitive to ischemic stroke at low temperature. At lag 0-21 days, the RRs at -3℃ were 1.20 (95% CI:1.05-1.36) for men and 1.20 (95% CI:1.12-1.50) for visitors less than 65 years of age. In addition, the association between hot temperature and ischemic stroke admission was not found.

Conclusion Low temperature could increase the risk of ischemic stroke admissions of residents in Bieijing and there is a cumulative lag effect. The study findings suggest that residents pay attention to the health impact of low temperature and strengthen the prevention against ischemic stroke in cold weather.