The Relationship Between Meteorological Factors And Cardiovascular Disease In Changchun City

With the increase of climate change and air pollution,the number of cardiovascular diseases patients is increasing quickly.Changchun is located in the northeast of China.There is a lack of research on meteorological factors affecting cardiovascular diseases in this area.In the current study,the cardiovascular disease data from January 1,2009 to December 31,2012 and daily meteorological observation data of the corresponding year in Changchun City were collected.firstly,we use descriptive statistics to analyze the time distribution characteristics of the number of patients and meteorological factors,and use the methods of stepwise regression and multiple regression to derive the forecasting equations of meteorological factors affecting the incidence of cardiovascular diseases in Changchun City.Using GAM(generalized additive model)model to study the effects of temperature and relative humidity on the Relative Risk(RR)of cardiovascular disease,considering the lagged effects of meteorological factors on the disease for 1-7 days and stratifing age and gender.The main results are as follows:(1)The effect of temperature on the total number of cardiovascular diseases in Changchun City showed a “U” shape.As the temperature gradually rises,the RR value decreases first and then increases,having a minimum point which is the optimum temperature.When the three temperature indicators were below their optimum temperatures,the daily maximum temperature had no significant effect on the number of cardiovascular diseases.The daily average temperature had no lag effec while the daily minimum temperature had the significant lag effect;when the three temperature indicators were higher than their optimum temperature,the daily average temperature and the daily maximum temperature had no lag effects,and the daily minimum temperature had the significant lag effect.The cold effect is greater than the warm effect in Changchun City.(2)The effect of daily average temperature to different groups of patients is not obvious.Daily maximum temperature and the daily minimum temperature have significant lagging effect.When the temperature is below the optimal temperature,the daily average temperature has a greater impact on the non-elderly patients than the elderly patients.When the temperature is above the optimal temperature,the impact on non-elderly people is smaller than that the elderly.The effect of the daily average temperature was stronger on females than on males;the daily maximum temperature has more influence on females than males and it has more influence on the elderly patients than the non-elderly;the daily minimum temperature have more influence on the elderly patients than the non-elderly;when temperature is below the optimal temperature,the daily minimum temperature has less influence on females than males.When temperature is above the optimal temperature,the minimum daily temperature has less influence on females is less than that of males.(3)Daily average temperature and daily minimum temperature have obvious lag effects on different groups in warm season than cold season,while the daily maximum temperature have no consistent influence.The influence of daily average temperature to the total number of patients is stronger in the cold season than that in warm season,and stronger on the elderly patientsin warm season than cold season;The influence of daily average temperature to non-elderly patients is stronger in warm season than in cold season;and effect on females was more pronounced in warm season than in cold season.The effect of daily maximum temperature change on different cardiovascular patients,when the maximum temperature below the optimal temperature maximum temperature have more influence on total number of patients,the elderly and the non-elderly patients in warm season than in cold season,and to females there is an opposite result.The effect of daily minimum temperature change on different cardiovascular patients,when the minimum temperature is below the optimal temperature,minimum temperature have more influence on total number of patients and elderly patients in cold season than in warm season.when the minimum temperature is above the optimal temperature,minimum temperature have more influence in warm season than in cold season,and for females and non-elderly patients,there is an opposite result.(4)The response curve of relative humidity and cardiovascular diseaseshowed an inverted “U” shape.The impact of relative humidity on different groups of cardiovascular diseases,extremum points generally is about 70 of relative humidity.On the left side of the extremum point,the maximum RR that relative humidity affects the number of females is 1.010,and men is 1.007.On the right side of the extremum point,the minimum RR relative humidity on femalesis 0.992,and males is 0.993.The response of relative humidity changes to males is more sensitive than to females.On the left side of the extremum point,the maximum RR that relative humidity affects the number of elderly is 1.007,and is non-elderly also1.007;On the right side of the extremum point,the minimum RR that relative humidity affects the number of elderly people is 0.992,and non-elderly people is 0.993.Therefore,the effect relative humidity to different groups have no much difference.(5)The synergistic effect of daily average temperature,daily maximum temperature with daily average relative humidity in Changchun City have significant impacts on all the number of cardiovascular diseases and females.The synergistic effect of the daily minimum temperature with daily average relative humidity have significant impact on the number of elderly people,females and all the number of cardiovascular diseases.Analysis the Smooth surface map of meteorological factors and temperature influences the number of cardiovascular diseases in ChangChong,we found at high temperature-low humidity,the synergistic effect of the daily average temperature and relative humidity have significant effect on the number of patients;high temperature 、low temperature and near 70 % of relative humidity,the synergistic effect of daily maximum temperature 、daily minimum temperature and relative humidity have significant effect on the number of number of patients.(6)We established stepwise regression equations for meteorological factors and cardiovascular diseases in Changchun City and used historical data to to check the forecasting results.After comparing the proportion that passed the test we found that a smooth stepwise regression equation had the best forecast effect.