Effect of air-pollutants and environmental factors on COPD
exacerbations: time series analysis stratified by age and concentration
of pollutants
Abstract
Background: Chronic obstructive pulmonary disease (COPD) exacerbation
(CE) is characterized by the rapid deterioration of respiratory symptoms
caused by air pollution, but there have been no comprehensive studies
with regard to the age-stratified effect of air pollution. We
investigate the short-term effects of air pollution and environmental
factors on CE. Methods: By merging the individualized environmental data
and Korea’s National Health Insurance cohort, we conducted Quasi-Poisson
analysis to evaluate the effects of air pollutants and environmental
factors on CE. Results: From January 2007 to December 2012, a total of
15110 CE events occurred, which showed seasonal dynamics in CE events,
air pollutants (particulate matter less than 10 µm (PM10), NO2, SO2) and
environmental factors (wind speed (WS), solar sunshine (SS)). The only
factor affecting CE was PM10, and this occurred on lag days 4, 5, and 6
and had a peak hazard ratio (HR) of 1.0404 on lag day 5. PM10 also had a
lag-cumulative effect on CE risk from lag day 6 to lag day 10. In
subgroup analysis on age and level of parameters, each factor had a
different significant effect on CE on different lag days. Conclusions:
PM10 uniquely affects CE at lag-specific day 5 (from lag day 4 to lag
day 6). PM10 also had a lag-cumulative effect on CE risk which showed a
pattern proportional to the concentration of PM10. Considering the
subgroup analysis, we need to devise different strategies for air
pollutants and age for patients with COPD exacerbation.