Comparison of the effects of air pollution on outpatient and inpatient visits for asthma: a population-based study in Taiwan.
BACKGROUND
A nationwide asthma survey on the effects of air pollution is lacking in Taiwan. The purpose of this study was to evaluate the time trend and the relationship between air pollution and health care services for asthma in Taiwan.


METHODS
Health care services for asthma and ambient air pollution data were obtained from the National Health Insurance Research database and Environmental Protection Administration from 2000 through 2009, respectively. Health care services, including those related to the outpatient and inpatient visits were compared according to the concentration of air pollutants.


RESULTS
The number of asthma-patient visits to health-care facilities continue to increase in Taiwan. Relative to the respective lowest quartile of air pollutants, the adjusted relative risks (RRs) of the outpatient visits in the highest quartile were 1.10 (P-trend  = 0.013) for carbon monoxide (CO), 1.10 (P-trend  = 0.015) for nitrogen dioxide (NO2), and 1.20 (P-trend <0.0001) for particulate matter with an aerodynamic diameter ≦ 10 µm (PM10) in the child group (aged 0-18). For adults aged 19-44, the RRs of outpatient visits were 1.13 (P-trend = 0.078) for CO, 1.17 (P-trend = 0.002) for NO2, and 1.13 (P-trend <0.0001) for PM10. For adults aged 45-64, the RRs of outpatient visits were 1.15 (P-trend = 0.003) for CO, 1.19 (P-trend = 0.0002) for NO2, and 1.10 (P-trend = 0.001) for PM10. For the elderly (aged ≥ 65), the RRs of outpatient visits in were 1.12 (P-trend  = 0.003) for NO2 and 1.10 (P-trend  = 0.006) for PM10. For inpatient visits, the RRs across quartiles of CO level were 1.00, 1.70, 1.92, and 1.86 (P-trend  = 0.0001) in the child group. There were no significant linear associations between inpatient visits and air pollutants in other groups.


CONCLUSIONS
There were positive associations between CO levels and childhood inpatient visits as well as NO2, CO and PM10 and outpatient visits.
Department of Pediatrics, Chung Shan Medical University Hospital, Taichung City, Taiwan R.O.C; School of Medicine, Chung Shan Medical University, Taichung City, Taiwan R.O.C.
Hui-Hsien
HH
Pan
Department of Pediatrics, Chung Shan Medical University Hospital, Taichung City, Taiwan R.O.C; Department of Health Policy and Management, Chung Shan Medical University, Taichung City, Taiwan R.O.C.
Chun-Tzu
CT
Chen
Department of Pediatrics, Chung Shan Medical University Hospital, Taichung City, Taiwan R.O.C; School of Medicine, Chung Shan Medical University, Taichung City, Taiwan R.O.C.
Hai-Lun
HL
Sun
Department of Pediatrics, Chung Shan Medical University Hospital, Taichung City, Taiwan R.O.C; School of Medicine, Chung Shan Medical University, Taichung City, Taiwan R.O.C.
Min-Sho
MS
Ku
Department of Pediatrics, Chung Shan Medical University Hospital, Taichung City, Taiwan R.O.C.
Pei-Fen
PF
Liao
School of Medicine, Chung Shan Medical University, Taichung City, Taiwan R.O.C.
Ko-Hsiu
KH
Lu
Department of Pediatrics, Chung Shan Medical University Hospital, Taichung City, Taiwan R.O.C; School of Medicine, Chung Shan Medical University, Taichung City, Taiwan R.O.C.
Ji-Nan
JN
Sheu
Institute of Public Health, Department of Public Health, Chung Shan Medical University, Taichung City, Taiwan R.O.C.
Jing-Yang
JY
Huang
Department of Health Policy and Management, Chung Shan Medical University, Taichung City, Taiwan R.O.C.
Jar-Yuan
JY
Pai
Department of Pediatrics, Chung Shan Medical University Hospital, Taichung City, Taiwan R.O.C; School of Medicine, Chung Shan Medical University, Taichung City, Taiwan R.O.C.
Ko-Huang
KH
Lue
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000393:Air Pollutants / Q000009:adverse effects / Q000032:analysis*; D000397:Air Pollution / Q000009:adverse effects / Q000032:analysis*; D001249:Asthma / Q000453:epidemiology* / Q000209:etiology; D002648:Child; D002675:Child, Preschool; D004784:Environmental Monitoring; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007297:Inpatients; D008297:Male; D008875:Middle Aged; D010045:Outpatients; D013624:Taiwan / Q000453:epidemiology; D055815:Young Adult
D000393:Air Pollutants