Association Between Air Pollution Exposure And The Risk Of Tuberculosis Admissions

ObjectiveAs one of the top ten causes of death worldwide and the leading cause of death from a single infectious disease,tuberculosis poses a great burden on human health.The purpose of this study was to explore the association between short-term air pollutants exposure and the risk of tuberculosis（TB）admissions in Hefei city.Besides,subgroup analyses were also conducted to identify the susceptibility of different populations to air pollution.It can provide useful information for the policy makers to formulate targeted prevention and control measures for TB.MethodWe collected the admission data from Anhui Institute of Tuberculosis Prevention and Control in Hefei from 2014 to 2018.Besides,the air pollutants（particulate matter,sulfur dioxide,nitrogen dioxide,ozone,carbon monoxide）and meteorological data was obtained from ten fixed meteorological monitoring stations in Hefei.After establishing a time series data set for tuberculosis admissions,we used Spearman rank correlation analysis to explore the correlation between atmospheric pollutants and meteorological factors.A distributed lag nonlinear model（DLNM）combined with time-stratified case-crossover design was used to analyze the correlation between air pollutant exposure and risk of TB admission.The admission day of patients was selected as the case group,and the same days of the other three weeks in the same month of the admission day were used as the control group during the exposure window（January 1,2014 to December 31,2018）.We performed stratified analyses by patients’gender（male,female）,age（0-17 years old,18-64 years old,≥65 years old）and admission season（warm season,cold season）to identified vulnerable subgroups.Finally,we evaluated the stability of the model by establishing a multi-pollutant model,adjusting the degree of freedom（df）of meteorological factors and increasing the concentration of pollutant exposure.Results（1）A total of 23,515 confirmed TB patients were included in this survey,including15,003 males and 8,512 females,with a gender ratio of 1.76.Younger people（0–17years old）,adults（18–64 years old）,and elder people accounted for 3.81%,79.32%and 16.87%of the total admissions,respectively.There was little difference between the number of admissions in the cold season（11,821）and the warm season（11,694）.（2）We observed a statistically significant association between air pollutant exposure and the risk of TB admission in the single-pollutant model except CO.The maximum lag-specific relative risk（RR）of TB outpatient visits were 1.003（95%CI:1.001–1.006,lag 11 day）for each 10μg/m3increase in PM_2.5;1.002（95%CI:1.001–1.004,lag 10 day）for each 10μg/m3increase in PM₁₀;0.852（95%CI:0.765–0.949,lag 14 day）for each 10μg/m3increase in SO₂,1.005（95%CI:1.001–1.010,lag 4 day）for each 10μg/m3increase in NO₂,1.006（95%CI:1.001–1.011,lag 1day）for each 10μg/m3increase in O₃ in the single-pollutant model.（3）Subgroup analyses showed that there was a statistically significant association between the NO₂ and O₃ exposure and the risk of TB admission in male patients（NO₂:RR=1.006,95%CI=1.001,O₃:RR=1.007,95%CI=1.001,1.013）.After stratified by age,we found that the effects of air pollutants exposure varied across age groups except CO exposure.The adverse effects of PM_2.5,PM₁₀and NO₂ exposure were significant in adults（18-64 years old）and elder（≥65 years old）subgroups,and no significant association was found among younger people.Besides,the effects of SO₂and O₃ exposure were associated with the risk of TB admission in younger（0-17years old）and adult（18-64 years old）groups.The results of seasonal subgroup analysis suggested that exposure to PM_2.5,PM₁₀,SO₂,NO₂ and O₃ were associated with the risk of TB admission in cold seasons,while no similar effect was observed in warm season.In contrast,O₃ exposure was statistically associated with an increased risk of TB admission in warm season,and the risk was higher than that in cold season.（4）Sensitivity analysis showed the association between air pollutants exposure and the risk of TB admission changed without statistical significance after fitting the multi-pollutant model,changing the df of meteorological factors and the lag days in the model.ConclusionIn this study,we explored the association between air pollutant exposure and TB admission using distributed lag nonlinear model combined with case-crossover design.The results suggested that exposure to PM_2.5,PM₁₀,NO₂ and O₃ are positively associated with the risk of TB admission,while exposure to SO₂ was negatively correlated with the TB admission.Besides,we did not observe statistically significant association between CO exposure and the risk of TB admission.Therefore,in order to protect TB patients and reduce the burden of disease,it is necessary for government departments to develop targeted publicity and seasonal prevention measures in response to the local air quality conditions.