A Study On The Impact Of Weather Changes On Cardiovascular System Diseases

In the background of global climate change, more attention has been paid to the associations between the intensified sudden change in weather and frequent meteorological disasters and human health, which has been one of heat issues in emerging interdisciplinary field of research. Cardiovascular system disease, as the main cause of diseases and death, was found to be affected by the meteorological environment change. In this study, we collected the daily emergency room (ER) admissions, hospital admissions and mortality data for cardiovascular diseases from three key cities in different climate zones, respectively. Meteorological and environmental data were also obtained accordingly. A semi-parametric generalized additive model (GAM) was used to analyze the exposure-effect of average temperature, diurnal temperature range (DTR) and temperature change in 24 hours on the morbidity and mortality of cardiovascular diseases. The symmetric bidirectional case-crossover design was also used to analyze the impact of heat waves and cold waves on the morbidity and mortality of cardiovascular diseases. The aim of this study is to confirm and evaluate the exposure-effect relationship between weather change and cardiovascular disease morbidity and mortality in order to provide the theory basis for the service of medical meteorological forecast for cardiovascular disease in future. The results are as follows.(1) Seasonal peaks in the incidence of ER admissions and hospital admissions for total cardiovascular disease were mainly in spring and autumn. Cerebrovascular disease was the main cause of illness, male and people under the age 65 were the major groups of total admissions. The mortality distribution of total cardiovascular disease showed V-shaped in Nanjing, with the highest mortality in winter and the lowest mortality in summer. Average temperature, DTR and temperature change in 24 hours were found to be related to cardiovascular disease morbidity and mortality, and these associations existed significant lag effect in three key cities.(2) Significant associations were found between average temperature and cardiovascular disease morbidity and mortality in three key cities. The threshold effects of temperature for morbidity and mortality varied by cites. The threshold temperature range of ER admissions in Beijing was from 7 to 14℃, the threshold temperature range of hospital admissions in Lanzhou was from 6 to 17℃, the threshold temperature of mortality in Nanjing was 25℃. The effect estimates of temperature on cardiovascular disease morbidity increased above the threshold temperature greater than below the threshold temperature, the result for cardiovascular disease mortality was just the opposite. In summer, the risk of cardiovascular disease incidence in female and people aged 75 years and older was decreased as the temperature increase, and the risk was increased in male and people under the age 65 as the temperature increase in winter.(3) Diurnal temperature range (DTR) was significantly associated with cardiovascular disease mortality and morbidity in this study. Generally, a 1 ℃ increase in the greatest lag-day of DTR corresponded to an increase of 0.57%-0.98% in ER admissions for cardiovascular disease in Beijing, and 0.97%-2.25% in hospital admissions for cardiovascular disease in Lanzhou, and 1.06% in mortality in Nanjing, respectively. Male and people aged 65 years and older were associated more strongly with DTR than female and people under aged 65. DTR which is considered as an important index of climate change and variability has a certain reference value for changes of human living environment and human health.(4) A significant change in temperature between neighboring days has an adverse impact on cardiovascular disease morbidity and mortality. The increase in temperature between neighboring days has greater effect on cardiovascular disease morbidity and mortality than the decrease in temperature between neighboring days. In total, a 1 ℃ increase in temperature between neighboring days was associated with the greatest lag-day percentage change of risk of 0.66% -1.21%,0.73% -1.53% and 0.74% for ER admissions in Beijing, hospital admissions in Lanzhou and mortality in Nanjing, respectively. For those 65 years and older, the effect of temperature change in 24 hours on cardiovascular disease morbidity was greater than in those aged under 65 years.(5) In our study, both heat wave and cold spell were associated with increased risk of cardiovascular disease mortality and morbidity. The results showed that the hot effect decreased gradually with lag days, with the greatest effect at current day, while the cold effect increased gradually with lag days, with the highest effect at lag 0-3 day. There were different effects of heat wave on gender and age groups between in Beijing and in Lanzhou. The cold spell had a larger impact on cardiovascular disease morbidity among those 65 years and older than the impact among younger. Other meteorological factors and air pollutants had the effect modifier of extreme temperature to enhance the impact of heat wave and cold spell on cardiovascular disease mortality and morbidity.(6) The modifying effects of season and demographic characteristics on temperature, DTR and temperature change in 24 hours were observed in this study.In a word, weather pattern transformations and sudden change of meteorological factors have the significant impact on cardiovascular disease mortality and morbidity. In particular, the effects on patients with cardiovascular diseases and the elderly were significant with the percentage change of mortality and morbidity. In this study, we used advanced statistical methods to analyze the impact of extreme temperature and weather change on cardiovascular disease morbidity and mortality in three key cities in different climate zones. We found the changes in temperature and the extents of variation were significantly associated with cardiovascular disease compared with respiratory disease, the seasonal peaks in incidence and mortality of cardiovascular disease also occurred mainly in those months with active cold and warm air in spring and autumn. These important conclusions of this study could not only provide the theory basis and technical support for the service of medical meteorological forecast, but also provide the scientific basis for helping increase our public awareness and built an integral warning and forecasting system in order to minimize the risk of extreme temperature and weather change on cardiovascular disease morbidity and mortality.