Association Between Air Pollutants And Psoriasis Daily Outpatients In Hefei City From 2015 To 2019: A Time Series Study

Objective This study quantitatively analyzed the short-term impact of air pollutants in Hefei on the number of psoriasis daily outpatients,and modeled hierarchically according to gender,age and season,in order to provide a scientific basis for disease prevention and control in the region.Methods The number of daily outpatient cases and related data in two large tertiary hospitals in Hefei City from January 1,2015 to December 31,2019 were collected.In this study,the monitoring data of the average daily concentration of atmospheric pollutants(PM_2.5,PM₁₀,CO,O₃,NO₂,SO₂)were collected from the Hefei Environmental Protection Bureau during the same period.Meteorological data was obtained by the Hefei Meteorological Bureau.After controlling long-term trend,day of the week effect（DOW）,holiday effect and common meteorological factors（average temperature,relative humidity,sunshine time）,a distributed lag nonlinear model based on the generalized additive model was used to analyze the exposure response relationship and lag effect between air pollutants and psoriasis daily outpatients.The relative risk（RR）and 95%confidence interval（CI）for each 10μg/m³increase in pollutant concentration were calculated,and subgroup analysis was performed by sex,age and season.Results（1）From 2015 to 2019,the total number of psoriasis outpatients in two large tertiary hospitals in Hefei City was 54 064,with an average of 30 patients per day.In the 5years,there were 5 169 people aged 0-17.The number of people aged 18-39 was the largest,with 26 012 people,accounting for 48.11%.There are 19 261 people aged 40-64,and 3 622people aged 65 or above.（2）The exposure-response relationship between changes in SO₂ concentration and the number of psoriasis outpatients showed an inverted U-shaped relationship.NO₂ showed a U-shaped relationship,and O₃ 8h showed an S-shaped trend.（3）In the single-pollutant model,the lag effect of each 10μg/m³ increase in SO₂ and NO₂concentration on the number of psoriasis outpatients was the most obvious in lag0d,lag0d and lag04d,lag05d.The RR values were 1.027（95%CI:1.009-1.046）,1.013（95%CI:1.007-1.020）,1.079（95%CI:1.021-1.141）and 1.044（95%CI:1.021-1.067）,respectively.The effect of each 10μg/m³ increase in O₃-8h concentration on the number of psoriasis outpatients was most significant at lag0d and lag06d,and the number of daily outpatients was decreased to 0.996（95%CI:0.992-0.999）and 0.983（95%CI:0.971-0.996）.（4）Gender stratification analysis in single pollutant model showed that with the increase of SO₂ and NO₂ concentrations in female psoriasis patients,the risk of daily outpatients increased.Among them,lag0d,lag0d,lag06d and lag05d had the most obvious lag effects.The RR values were 1.040（95%CI:1.012-1.068）,1.021（95%CI:1.011-1.031）,1.151（95%CI:1.045-1.269）and 1.073（95%CI:1.037-1.110）,respectively.In male patients,only O₃ was observed to reduce the risk of psoriasis outpatients.For each 10μg/m³ increase in O₃8h concentration,the RR values of male psoriasis patients at lag0d and lag06d were 0.993（95%CI:0.988-0.997）and 0.972（95%CI:0.957-0.988）.（5）The age stratified analysis results of single pollutant model showed that each 10μg/m³increase of SO₂ and O₃ concentration only had different influenced on psoriasis outpatients aged 18-39.Among them,SO₂ reached the largest effect value in lag0d and lag05d,which were 1.030（95%CI:1.004-1.057）and 1.101（95%CI:1.011-1.198）,respectively.O₃ was the strongest protective factor in lag0d and lag05d,which were 0.994（95%CI:0.989-0.998）and0.976（95%CI:0.960-0.993）.NO₂ had an impact on psoriasis outpatients of all ages.（6）The stratified analysis results of single pollutant model showed that each 10μg/m³increase in the concentration of SO₂ and NO₂ in the cold season had the greatest impact on the number of psoriasis outpatients at lag0d and lag05d,and the RR values were 1.034（95%CI:1.010-1.058）,1.024（95%CI:1.017-1.031）,1.109（95%CI:1.014-1.213）and 1.084（95%CI:1.054-1.114）.The single-day lag effect of O₃ was shown as a protective factor,and the cumulative effect value was shown as a risk factor in lag01d,which turned into a protective factor as time increases.In the warm season,the lag effect of SO₂ of 5 to 7 days（lag5-lag7）was a protective factor,and the cumulative lag of 1 to 5 days（lag01-lag05）was a risk factor.（7）The results of double-pollutant model analysis showed that after SO₂ was included in NO₂and O₃,the risk of psoriasis outpatients was not statistically significant.After the inclusion of SO₂ and O₃,the concentration of NO₂ increased by each 10μg/m³,the risk of psoriasis outpatients increased,and the RR value and its 95%confidence interval were 1.036（95%CI:1.004-1.069）and 1.051（95%CI:1.022-1.080）.When O₃ concentration was controlled,only after the inclusion of NO₂,the risk of psoriasis outpatients was reduced for each 10μg/m³increase.the RR value is 0.982（95%CI:0.969-0.996）,and the inclusion of SO₂ results is not statistically significant.（8）This study explored the stability of the model by adjusting the degrees of freedom of the average temperature,relative humidity,sunshine time（df=3-5）and time（df=5-8）in the model.The results indicated that the model was stable and the fitting effect was ideal.Conclusions From 2015 to 2019,air pollutants in Hefei had a short-term effect on the number of psoriasis outpatients,with hysteresis and cumulative effect.Women and patients aged 18 to 39 years were at higher risk of daily outpatient visits due to exposure to air pollution.The effect of air pollutants on the number of psoriasis outpatients was seasonal.The outpatient risk of SO₂ and NO₂ in cold season is higher than that in warm season.