Study On The Relationship Between Air Pollution And Daily New Hospital Admissions,Daily Outpatient And Emergency Visits Based On Distributed Lag Non-linear Model

Objective:To clarify the health effect relationship between air pollutant,daily new hospital admissions,daily outpatient and emergency visits in Changsha city,and screen representative pollutants,key diseases and sensitive population.Prepare medical resources and staff for changes in inpatient and emergency visits.Methods:New hospital admissions（hospitalization information includes ICD-10 code of main diagnosis,gender and age）,daily outpatient and emergency visits were collected from a hospital in Changsha from November 1,2016 to December 31,2019.Average daily concentrations of PM_2.5,PM₁₀,SO₂,NO₂,CO,O₃（the maximum 8-hour concentration）and meteorological data in the same period.Spearman rank correlation coefficient was used to quantify the correlation between daily total number of new hospital admissions,daily outpatient and emergency visits,air pollutants and meteorological factors.After controlling confounding factors,DLNM model was used to investigate the lag effect of six kinds of air pollutants on the daily total number of new hospitalizations,daily outpatient and emergency visits,and the differences of health effects among different subgroups and seasons.Results:（1）The main pollutants during the study period were PM_2.5and PM₁₀,and there were significant seasonal differences among air pollutants.（2）Except for diseases of blood system,circulatory system and respiratory system,other system diseases,patients of different genders and ages,total number of daily new inpatients,daily outpatient and emergency visits were higher in cold season than in warm season.SO₂had the greatest influence on daily emergency visits,daily outpatient visits were mainly affected by CO,and daily new inpatients were related to SO₂and CO.（3）DLNM model analysis showed that（1）SO₂had the greatest influence on daily emergency visits,daily outpatient visits were mainly affected by CO,and daily total number of new hospital admissions were related to SO₂and CO.（2）PM_2.5mainly affected the daily new hospitalization of patients with hematological diseases and female dermatological diseases aged16-65 years,while SO₂mainly affected the daily new hospitalization of patients with dermatological diseases aged≥66 years.O₃mainly affected the daily new hospital admissions of musculoskeletal system diseases in0-15 years old,NO₂mainly affected the daily new hospital admissions of endocrine system diseases in 0-15 years old,while CO had an impact on the daily new hospital admissions of endocrine system,nervous system,circulatory system,digestive system and skin system diseases.PM₁₀had no significant effect on the number of daily new hospital admissions in different disease systems and in different genders and ages.（4）Sensitivity analysis shows that the model is still robust when the degree of freedom of confounding factors is changed.Under different seasons,the lag effect of daily new hospital admissions,outpatient and emergency visits and air pollutants was different.Conclusions:（1）The main air pollutants in Changsha during the study period are PM_2.5and PM₁₀.（2）There was significant difference in the health effect relationship between the six kinds of air pollutants and the daily total number of new inpatients,outpatient and emergency visits,and it was affected by season.（3）Diseases of the skin system,circulatory system,musculoskeletal system and endocrine system are the main diseases affected.Women and people aged 16-65 are sensitive groups.（4）Therefore,the lag effect of air pollutants on different diseases and population characteristics should be considered when the relevant departments of Changsha formulate environmental protection policies.