Association Study Between Short-term Air Pollution And Readmission Risk For Rheumatoid Arthritis And Systemic Lupus Erythematosus

ObjectiveRheumatoid arthritis（RA）can cause symmetrical and aggressive joint inflammation in the hands,feet and other joints.Systemic lupus erythematosus（SLE）often involves damages to multiple organs or systems including skin,bones and viscera.Both of them are typical chronic autoimmune diseases（ADs）.As a tractable metric of quality of healthcare,hospital readmissions shortly after discharge has been considered as a sign of poor patient prognosis.It has been shown that air pollution may be related to the etiology of ADs,but its relationship with the readmission risk of RA and SLE has not been determined.This study aimed to describe the time distribution of daily hospital readmissions for RA and SLE in Hefei from 2014 to 2018,explore the short-term effect of exposure to air pollutants on the readmission risk of RA and SLE patients,and further define the high-risk subgroups and susceptible seasons,so as to provide theoretical basis for effective prevention and control of RA and SLE.MethodsIn this ecological study,the daily hospital readmissions data of RA and SLE patients were provided by the Department of Rheumatology,the First Affiliated Hospital of Anhui Medical University and the First Affiliated Hospital of University of Science and Technology of China.Daily data on air pollutants(PM_2.5,PM₁₀,NO₂,SO₂,CO and O₃)and meteorological variables（RH and MT）were obtained from China Environmental Monitoring Station and China Meteorological Data Service Center,respectively.Through the combined use of distributed lag nonlinear models and quasi-Poisson generalized linear regression,RH,MT,long-term trends,DOW and holidays were controlled.The subgroup analysis was further stratified by sex,age and season.The single-day and cumulative lag effects of short-term exposure to high concentrations of air pollutants（P90,90th percentile）on RA and SLE patients were caculated against the lowest risk of readadmissions.In addition,subgroup analysis was conducted by gender（male vs.female）,age（<65 years old vs.≥65 years old）,and season（warm season vs.cold season）to further clarify vulnerable subgroups and seasonal differences.ResultsFrom 2014 to 2018,the main air pollutants exceeding the ambient air quality（AQI）standards in Hefei were PM₁₀,NO₂and PM_2.5.A total of 1153 RA readmissions and1456 SLE readmissions were recorded,most of which were female patients.According to the lowest RA readmissions risk concentration(43μg/m³for PM_2.5),the highest single-day RR appeared at lag1（RR=1.09,95%CI:1.01-1.19）.According to the lowest RA readmissions risk concentration（51μg/m³for NO₂）,the highest single-day RR appeared at lag4（RR=1.11,95%CI:1.05-1.17）.Females and the elderly appeared to be more vulnerable to exposure to high concentrations of PM_2.5and NO₂.High-concentration PM_2.5and NO₂in cold seasons were consistently significantly associated with increased risk of RA readmissions.None of the associations between PM₁₀,SO₂,CO and O₃exposure and the risk of RA readmissions were statistically significant.Referring to the lowest SLE readmissions risk concentration(54μg/m³for PM_2.5),the single-day effect peaked at lag0（RR=1.15,95%CI:1.04-1.26）.Females and the patients aged<65 years were more vulnerable to high-concentration PM_2.5exposure.Referring to the lowest SLE readmissions risk concentration（49μg/m³for NO₂）,the single-day effect peaked at lag2（RR=1.05,95%CI:1.01-1.10）.Females were more vulnerable to high-concentration NO₂exposure.In cold seasons,both of the effects of high-concentration PM_2.5and NO₂were significant.Referring to the lowest SLE readmissions risk concentration（17μg/m³for SO₂）,the single-day effect peaked at lag8（RR=1.03,95%CI:1.01-1.05）.Males and the patients aged<65 years were more vulnerable to high-concentration SO₂exposure.None of the associations between PM₁₀,CO and O₃exposure and the risk of SLE readmissions were statistically significant.ConclusionsFrom 2014 to 2018,the main air pollutants exceeding the AQI standards in Hefei were PM₁₀,NO₂and PM_2.5.Exposure to high concentrations of PM_2.5and NO₂was related to the increased risk of RA readmissions.Women and the elderly were the vulnerable groups,and the adverse effect of NO₂was significant only in the cold season.There were significant associations between exposure to high concentrations of PM_2.5,NO₂,SO₂and the increased risk of SLE readmissions.The adverse effects of PM_2.5and NO₂were significant for women and in cold seasons.On the contrary,the adverse effect of SO₂was more significant for males and exhibited no seasonal differences.