Association Of Air Pollution On Hospitalization For Schizophrenia And Disease Burden Assessment

Objective:This study aims to investigate the association between air pollution and hospitalization for schizophrenia from three aspects.First,based on the air pollution data from 2015 to 2019 in Qingdao,the effects of particulate matter with different sizes on schizophrenia hospital re-admissions were quantitatively evaluated.Second,daily excessive concentration hours(DECH)at the hourly scale were used to evaluate the association between fine particulate matter(PM₂.5)and hospital admissions for schizophrenia.Third,we investigated the association between six air pollutants with schizophrenia admissions,and quantified their attributable risk and disease burden.Methods:Daily schizophrenia admission data from January 1,2015 to December 31,2019,were extracted from Qingdao Mental Health Center.Daily maximum 8-h average of O3 and daily 24-h mean concentrations of air pollutants(PM₂.5,PM₁0,SO₂,NO₂ and CO)were acquired from nine national air quality monitoring stations in Qingdao.The concentrations of particles with aerodynamic diameters between 2.5-10?m(PM₂.5-10)are obtained by subtracting the concentration of PM₁0 and PM₂.5.In addition,hourly PM₂.5data from 2016 to 2018 were collected to calculate DECH.Time series design was applied in this study.In the first part,we took the schizophrenia hospital re-admissions from 2015 to 2019 as the research object,and used the distributed lag nonlinear model to analyze the association between particulate matter with different sizes(PM₁0,PM₂.5-10,PM₂.5)and schizophrenia re-admissions;In the second part,the generalized linear modelwas used to compare and analyze the effects of daily mean and five different thresholds(10?g/m~3,15?g/m~3,20?g/m~3,25?g/m~3,35?g/m~3)DECH indexes(DECH-10,DECH-15,DECH-20,Dech-25,DECH-35)on hospital admissions for schizophrenia during the study period(2016-2018);In the third part,we used generalized additive model to analyze the exposure-response association and attributable risk of six air pollutants on schizophrenia hospitalizations,then calculated the economic burden due to the excessive exposure of air pollution by using the cost of illness approach.Results:Part I: The association between different sizes of particulate matters and schizophrenia re-admissions A total of 6,220 schizophrenia hospital re-admissions were included during the study period(2015-2019).The daily mean concentrations of PM₁0,PM₂.5-10 and PM₂.5were 82.43?g/m~3,41.10?g/m~3,41.33?g/m~3,respectively.According to the minimum akaike information criterion(AIC),we selected 6 days as the maximum lag days for different sizes of particulate matters in the model.For an interquartile range(IQR)increase in concentration of PM₂.5,the single-day lag association appeared to be statistically significant from lag1(RR=1.04,95% CI: 1.00–1.08)to lag4(RR=1.04,95%CI: 1.01–1.07),with the maximum effect at lag3(RR=1.05,95% CI: 1.01–1.09).In the cumulative lag association,the significant effects lasted from lag03 to lag06,with the maximum effect at lag06(RR=1.25,95% CI=1.05–1.49).For per IQR increase in concentrations of PM₂.5-10,the single day lag association remained to be statistically significant from lag3 to lag4.But we did not find significant associations for the cumulative lag days.In the PM₁0 model,the lag association appeared to be statistically significant from lag2 to lag4,and lag04 to lag06,with the maximum effect at lag05(RR=1.23,95% CI=1.04–1.46).Subgroup analysis showed that males and younger individuals(<45 years)appeared to be more sensitive to atmospheric particulate matters.Part II: Assessment of fine particulate matter and hospital admissions for schizophrenia based on an hour-scale index: daily excessive concentration hours There were 6,721 hospital admissions for schizophrenia from 2016 to 2018.Using the hourly PM₂.5 data during the study period,five threshold standards were set for DECH calculation,including 10?g/m~3,15?g/m~3,20?g/m~3,25?g/m~3 and 35?g/m~3,which were defined as DECH-10,DECH-15,DECH-20,DECH-25 and DECH-35,respectively.There was a high correlation between daily mean and PM₂.5 DECH(rs>0.9).We got highly similar estimated effects across daily mean and PM₂.5 DECH,with significant effects on schizophrenia observed only at lag5 and lag05.At lag5,for an IQR increase in concentration of daily mean,DECH-10,DECH-15,DECH-20,DECH-25 and DECH-35,the corresponding RR and 95%CI were 1.08(1.03-1.14),1.07(1.02-1.12),1.07(1.02-1.12),1.06(1.01-1.11),1.06(1.01-1.10)and 1.04(1.01-1.07),respectively.At lag05,the corresponding results were 1.12(1.01-1.25),1.12(1.01-1.25),1.12(1.00-1.25),1.11(1.00-1.23),1.10(1.00-1.21)and 1.07(1.00-1.14),respectively.Significant effects of daily mean and PM₂.5DECH on schizophrenia admissions were found only in the cold season,but the difference between seasonal groups was not statistically significant.We also found that the attribution risk of DECH-10,DECH-15,DECH-20,DECH-25 and DECH-35 were 10.49%,8.97%,7.71%,6.64% and 5.00%,which were all slightly higher than that of daily mean at various thresholds: 10.40%,8.84%,7.42%,6.22% and 4.37%,respectively.Part III: Short-term effects and economic burden assessment of ambient air pollution on hospitalizations for schizophrenia A total of 10,893 schizophrenia admissions were collected during the study period2015-2019.Our results showed that for a 10?g/m~3 increase in concentrations of PM₂.5,PM₁0,SO₂ and CO at lag5,the corresponding RR and 95%CI were 1.0160(1.0038-1.0282),1.0097(1.0018-1.0177),1.0738(1.0222-1.01280)and 1.0013(1.0001-1.0026),respectively.However,no significant effects of NO₂ and O3 were found.There were no statistically significant difference between different sex,age and season groups.12.41% of schizophrenia hospitalizations were attributed to exposure to air pollution(PM₂.5,PM₁0 and SO₂)exceeding World Health Organization(WHO)air quality standard,with the total economic burden of 94.11 million RMB during the study period.Among different pollutants,SO₂ brought the largest economic burden,reaching43.03 million RMB,then followed by PM₁0(26.91 million RMB)and PM₂.5(24.16 million RMB)Conclusion:(1)This study showed that short-term exposure to particulate matter with different sizes(PM₁0,PM₂.5-10,PM₂.5)significantly increased the risk of schizophrenia re-admissions.Males and younger people(<45 years old)appeared to be more susceptible to atmospheric particulate matters.(2)By employing daily mean and PM₂.5DECH metrics based on various thresholds as exposure indicators,we got highly similar estimated effects across daily mean and PM₂.5DECH.The results suggested that PM₂.5DECH could be used as a potential proxy for daily mean in the field of mental health.(3)Short-term exposure to PM₂.5,PM₁0,SO₂,and CO significantly increased the risk of hospital admissions for schizophrenia,and excessive exposure to PM₂.5,PM₁0 and SO₂ resulted in huge economic losses,suggesting that the government should continue to take more stringent measures to effectively reduce air pollution levels.