ABSTRACT
Objective@#To examine the impact of heat waves and cold spells on the incidence of hemorrhagic stroke, so as to provide insights into prevention of hemorrhagic stroke.@*Methods@#Data pertaining to the incidence of hemorrhagic stroke in Zibo City from 2015 to 2019 were collected from Shandong Provincial Management Information System for Chronic Diseases and Cause of Death Surveillance, and the meteorological data during the period from 2015 to 2019 were captured from National Meteorological Information Center of China. The air quality index (AQI) was collected from the National Daily Report of Urban Air Quality in China. Heat wave was defined as the highest daily temperature that was no less than the 90th percentile (P90), P92.5, P95 and P97.5 of the highest daily temperature in the warm season for at least 2, 3 or 4 days, and cold spell was defined as the lowest daily temperature that was no more than the P10, P7.5, P5 and P2.5 of the lowest daily temperature in the cold season for at least 2, 3 or 4 days. The effect of heat waves and cold spells on the incidence of hemorrhagic stroke was evaluated using a generalized additive model and described with relative risk (RR) and its 95%CI.@*Results@#A total of 8 844 case with first-onset hemorrhagic stroke were recorded in Zibo City from 2015 to 2019. The lowest daily temperature that was no more than P10, P7.5 or P5 of the lowest daily temperature in the cold season for at least two days, or that was no more than P10 or P7.5 of the lowest daily temperature for at least 3 days resulted a remarkably increased risk of hemorrhagic stroke (lowest RR=1.187, 95%CI: 1.031-1.366; highest RR=1.242, 95%CI: 1.042-1.480), and after adjusting the effect of daily mean temperature, the lowest daily temperature that was no more than P10 or P7.5 of the lowest daily temperature in the cold season for at least two days, or that was no more than P10 of the lowest daily temperature for at least 3 days resulted a remarkably increased risk of hemorrhagic stroke (lowest RR=1.236, 95%CI: 1.009-1.513; highest RR=1.274, 95%CI: 1.023-1.585). However, there was no significant association between heat waves and the risk of hemorrhagic stroke.@*Conclusion@#Cold spells may increase the risk of hemorrhagic stroke, while no significant association is examined between heat waves and the risk of hemorrhagic stroke.