Study On The Correlation Between Major Air Pollutants And Hospitalization Risk Of Cardiovascular Disease In Lanzhou

Objective:With the continuous advancement of urbanization,air pollution is becoming more and more serious.The correlation between air pollution and human health has naturally become one of the hot issues in the research of experts and scholars.Existing studies have shown that air pollution has a great impact on human cardiovascular system,but most of the studies focus on the impact of air pollution on residential cardiovascular disease outpatient or death cases,and relatively few studies on its impact on the number of hospitalizations.By understanding the concentration changes of major air pollutants(PM_2.5,PM₁₀,SO₂,NO₂,O₃8h,CO)and the fluctuation of hospitalizations for cardiovascular diseases in Lanzhou,this study analyzed the correlation between the number of hospitalizations for cardiovascular diseases and the concentration of air pollutants,and study the air pollutants that induce the occurrence and development of cardiovascular diseases and their delayed effects on the number of hospitalizations for cardiovascular diseases,so as to provide scientific basis for Lanzhou Municipal government to formulate effective air pollution control measures and prevent the occurrence of cardiovascular diseases.Methods:To collect hospitalization data of patients with cardiovascular diseases（including hypertension,ischemic heart disease and stroke）from 7 large general hospitals in Lanzhou during 2013-2020,as well as daily concentration of major air pollutants and meteorological data in Lanzhou during the same period,and carry out the following work:（1）Descriptive analysis was made on air pollutant concentration,meteorological factors and hospitalizations of cardiovascular diseases in Lanzhou during the target period,and Spearman rank correlation method was used to analyze the correlation between air pollutants and meteorological factors.（2）Distributed Lag Nonlinear Model（DLNM）is used to quantitatively evaluate the expose-response-lag relationship between air pollutants and cardiovascular disease inpatients,and to investigate the influence of gender,age,season and other factors on the number of hospitalizations of common cardiovascular diseases.（3）Establish the dual pollutant model and the sensitivity analysis method of changing time degree of freedom to test the stability of the model results.Results:（1）Descriptive analysis1)From 2013 to 2020,a total of 309,561 patients were hospitalized due to cardiovascular diseases in 7 large general hospitals in Lanzhou,with an average of106 hospitalizations per day.The male to female ratio is about 1.44 to 1.More than half of the hospitalized patients were<65 years old,accounting for 55.94%.In terms of disease groups,patients with hypertension,ischemic heart disease and stroke accounted for 71.79%of the hospitalized patients with cardiovascular diseases.2)From 2013 to 2020,the average daily temperature was 11.13℃and the average daily relative humidity was 51.19%.The average concentrations of PM_2.5,PM₁₀,SO₂,NO₂,O₃8h and CO were 49.78μg/m³,114.69μg/m³,21.65μg/m³,45.91μg/m³,83.76μg/m³and 1.16 mg/m³,respectively.Did not exceed the"National ambient air Quality standards"in the secondary standard limit.The concentrations of PM_2.5,PM₁₀,SO₂and CO showed a seasonal trend of higher in winter and spring and lower in summer and autumn,while the concentration of O₃8h showed an opposite seasonal trend.（2）Correlation analysis between air pollutants and meteorological factorsDuring the study period,O₃8h concentration was negatively correlated with PM_2.5,PM₁₀,SO₂and CO concentration,but positively correlated with air temperature,and had no correlation with NO₂concentration.Except O₃8h,the other five air pollutants were positively correlated,and the correlation between PM_2.5and PM₁₀was the strongest,with correlation coefficient r=0.850.Air temperature was negatively correlated with the concentration of other pollutants except O₃8h.Relative humidity was negatively correlated with PM_2.5,PM₁₀,SO₂and NO₂concentrations,but had no obvious correlation with CO concentration and air temperature.（3）Effects of changes in air pollutant concentration on hospitalizations for common cardiovascular diseasesThere is a lag effect and a certain exposure-response relationship between the change of air pollutant concentration and the hospitalizations of common cardiovascular diseases in Lanzhou City:1)The analysis of total hospitalizations for cardiovascular diseases showed that when PM_2.5（lag03）,SO₂（lag3）,NO₂（lag03）and CO（lag03）concentrations increased by 10μg/m³（CO was 1 mg/m³）,the Relative Risk（RR）of hospitalizations for cardiovascular disease was 1.0013（95%CI:1.0003,1.0023）,1.0032（95%CI:1.0008,1.0056）,1.0037（95%CI:1.0024,1.0057）and 1.0909（95%CI:1.0366,1.1479）,respectively;PM₁₀and O₃8h had no significant harmful effect on the total number of hospitalizations for cardiovascular diseases during the lag period.2)Analysis of hospitalizations for hypertension showed that when the concentration of SO₂（lag3）,NO₂（lag03）and CO（lag3）increased by 10μg/m³（CO was 1 mg/m³）,the RR values of hypertension hospitalizations were 1.0044（95%CI:1.0013,1.0074）,1.0042（95%CI:1.0019,1.0064）and 1.0986（95%CI:1.0350,1.1661）,respectively.PM_2.5,PM₁₀and O₃8h had no significant harmful effect on the number of hypertension inpatients in the whole lag period.3)The analysis results of hospitalization for ischemic heart disease showed that except O₃8h,the other five pollutants had harmful effects on hospitalization for ischemic heart disease,every increase of PM_2.5（lag03）,PM₁₀（lag3）,SO₂（lag3）,NO₂（lag04）and CO（lag03）concentration was 10μg/m³（CO was 1 mg/m³）,RR values for ischemic heart disease were 1.0019（95%CI:1.0007,1.0030）,1.0003（95%CI:1.0001,1.0006）,1.0053（95%CI:1.0026,1.0080）,1.0049（95%CI:1.0031,1.0068）and1.1397（95%CI:1.0074,1.2055）.4)Analysis of hospitalizations for stroke showed that NO₂（lag03）concentration increased by 10μg/m³,the RR value of stroke hospitalizations was1.0024（95%CI:1.0008,1.0040）.PM_2.5,PM₁₀,SO₂,O₃8h and CO had no harmful effect on the number of stroke hospitalizations in the whole lag period.（4）Effects of air pollutants on hospitalizations of common cardiovascular diseases in different sexes and age groupsThe results showed that there were age and sex differences in the effects of air pollutant concentration changes on total hospitalizations for cardiovascular diseases,hypertension,ischemic heart disease,and stroke.1)The analysis results of total hospitalizations for cardiovascular diseases showed that PM₁₀and NO₂had a more significant harmful effect on women,that is,with the increase of pollutant concentration,women’s risk of hospitalization increases;PM_2.5,SO₂and CO have significant effects on males,and the risk of hospitalization increases with the increase of pollutant concentration.PM_2.5,NO₂and CO have more significant harm effect on<65 years old,PM₁₀and SO₂are more likely to harm≥65years old.O₃8h had no significant harmful effect on total hospital admissions for cardiovascular diseases in different sexes and age groups during the lag period.2)The results of the analysis of hypertension hospitalizations showed that PM₁₀and NO₂had more obvious harmful effect on males,SO₂and CO more easily affected females,and PM_2.5and O₃8h had no significant harmful effect on the hospitalizations of hypertension of different genders in the whole lag period.NO₂and CO have more significant harmful effect on<65 years old,while SO₂is more likely to affect≥65years old.PM_2.5,PM₁₀and O₃8h have no significant harmful effect on the number of hypertension hospitalizations in different age groups in the whole lag period.3)The results showed that PM_2.5,PM₁₀,SO₂,NO₂and CO had more significant harmful effects on women.PM_2.5and PM₁₀have a more significant harmful effect on people<65 years old,SO₂,NO₂and CO are more likely to harm people≥65 years old.O₃8h had no significant harmful effect on the number of hospitalizations for ischemic heart disease in different sex and age groups during the lag period.4)The analysis results of stroke hospitalizations showed that PM_2.5had a greater impact on women than men,NO₂had a more significant harmful effect on men,and the two pollutants were more likely to affect the group of<65 years old,and the other four pollutants had no harmful effect on stroke hospitalizations of different genders and age groups in the whole lag period.（5）Effects of air pollutants on hospital admissions for common cardiovascular diseases in different seasonsHospitalizations for cardiovascular disease,hypertension,ischemic heart disease,and stroke caused by air pollutants were associated with the season.1)Analysis results of total hospitalizations for cardiovascular diseases showed that NO₂and CO had harmful effects at lag02～05 days in cold season and at lag3 and lag03～04 days in cold season,while only O₃8h had an effect at lag4 days in warm season.No harmful effect of PM_2.5,PM₁₀and SO₂on the total hospitalization of cardiovascular diseases was observed in the whole lag period,regardless of the warm season and cold season.2)Analysis results of hypertension hospitalizations showed that SO₂had harmful effects at lag3 days,NO₂and CO had harmful effects at lag3 and lag03～lag04days in cold season,and other pollutants had no effect on hypertension hospitalizations during the whole lag period.In the warm season,the six pollutants had no significant harmful effect on the number of hypertension hospitalizations in the whole lag period.3)The results of hospitalization for ischemic heart disease showed that SO₂had harmful effects at lag3 and lag03～lag05 days,NO₂at lag01～lag07 days,and CO at lag3 and lag03～lag07 days in cold season.In warm season,PM₁₀only has influence when lag3 days;No harmful effects of PM_2.5and O₃8h were observed on hospitalizations of ischemic heart disease in the whole lag period,regardless of the warm and cold seasons.4)The analysis of hospitalizations for stroke showed that NO₂and CO had harmful effects at lag03～lag04 days in cold season;In warm season,only PM_2.5has harmful effect when lag03 days;PM₁₀,SO₂and O₃8h had no harmful effect on the number of hospitalizations of stroke in the whole lag period regardless of the warm season and cold season.Exposure response curves of air pollutants and hospitalization risk of common cardiovascular diseases.（6）Exposure response curves of air pollutants and hospitalization risk of common cardiovascular diseasesWhen the pollutant concentration with the strongest lag days was selected as the air pollutant exposure level for the number of inpatients with cardiovascular disease,hypertension,ischemic heart disease and stroke,the exposion-response curve of the six pollutants in Lanzhou on the inpatients with common cardiovascular disease was approximately linear,without threshold effect.With the increase of PM_2.5,PM₁₀,SO₂,NO₂and CO concentrations,RR values corresponding to hospitalizations for common cardiovascular diseases showed an increasing trend.（7）Sensitivity analysisBy building a dual pollutant model and changing the degree of freedom of time variable（df=6～10）,the sensitivity analysis showed that the relative risk RR value did not change much,which proved that the model had a certain stability and the results were credible.Conclusions:（1）From 2013 to 2020,the air quality of Lanzhou continued to improve,and the concentration of pollutants decreased year by year.The average daily concentration of six kinds of air pollutants did not exceed the national secondary standards.PM_2.5,PM₁₀,SO₂and CO concentrations showed a seasonal trend of high in winter and spring and low in summer and autumn,while O₃8h showed an opposite seasonal trend.（2）Short-term exposure to PM_2.5,PM₁₀,SO₂,NO₂and CO increased hospitalization risk of cardiovascular disease,hypertension,ischemic heart disease and stroke in Lanzhou residents.There are also differences in the influence of gender and age on the number of hospitalizations for common cardiovascular diseases.1)Analysis of cardiovascular diseases showed that PM₁₀and NO₂had a greater impact on women,while PM_2.5,SO₂and CO had the opposite effect.PM_2.5,NO₂and CO had a greater impact on hospitalization in the<65 age group,while PM₁₀and SO₂were more likely to affect the≥65 age group.2)Analysis of hypertension showed that short-term exposure to SO₂and CO was associated with a higher risk of hospitalization in hypertensive women than in men,while PM₁₀and SO₂increased the risk of hospitalization in men.SO₂has a greater effect on hospitalization in hypertensive patients≥65 years old,while CO and NO₂are more likely to affect hypertensive patients<65 years old.3)Analysis of ischemic heart disease showed that female patients had a higher risk of hospitalization than male patients with increased concentrations of PM_2.5,PM₁₀,SO₂,NO₂,and CO.PM_2.5and PM₁₀had a greater impact on hospitalization in patients with ischemic heart disease in the<65 age group,while SO₂,NO₂and CO were more likely to affect the≥65 age group.4)The analysis results of stroke showed that PM_2.5had a higher risk of hospitalization in female stroke patients than in male patients,while NO₂had a greater impact on male patients,and both pollutants had a greater impact on hospitalization in stroke patients<65 years old.（3）There was a certain seasonal pattern between air pollutants and total hospitalizations of cardiovascular diseases,hypertension,ischemic heart disease and stroke in Lanzhou,and most of them showed a strong harmful effect in the cold season.（4）The effects of the six pollutants on hospitalization risk of common cardiovascular diseases were approximately linear with no threshold effect.Except O₃8h,RR values increased with the increase of the concentration of each pollutant.