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Am J Respir Crit Care Med. 2016 Aug 15;194(4):429-38. doi: 10.1164/rccm.201510-1932OC.

Progression from Asthma to Chronic Obstructive Pulmonary Disease. Is Air Pollution a Risk Factor?

Author information

1
1 Child Health Evaluative Sciences, The Hospital for Sick Children, Toronto, Ontario, Canada.
2
2 Institute for Clinical Evaluative Sciences, Toronto, Ontario, Canada.
3
3 Dalla Lana School of Public Health, Toronto, Ontario, Canada.
4
4 Institute of Health Policy, Management, and Evaluation and.
5
5 Department of Geography and Planning, University of Toronto, Toronto, Ontario, Canada.
6
6 Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada.
7
7 Department of Medicine, Queen's University, Kingston, Ontario, Canada.
8
8 Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada.
9
9 Public Health Ontario, Toronto, Ontario, Canada.
10
10 CHAIM Research Centre, Carleton University, Ottawa, Ontario, Canada.
11
11 Department of Geography, University of Ottawa, Ottawa, Ontario, Canada.
12
12 Ontario Ministry of the Environment and Climate Change, Toronto, Ontario, Canada; and.
13
13 Institute for Heart and Lung Health, University of British Columbia, Vancouver, British Columbia, Canada.

Abstract

RATIONALE:

Individuals with asthma-chronic obstructive pulmonary disease (COPD) overlap syndrome (ACOS), have more rapid decline in lung function, more frequent exacerbations, and poorer quality of life than those with asthma or COPD alone. Air pollution exposure is a known risk factor for asthma and COPD; however, its role in ACOS is not as well understood.

OBJECTIVES:

To determine if individuals with asthma exposed to higher levels of air pollution have an increased risk of ACOS.

METHODS:

Individuals who resided in Ontario, Canada, aged 18 years or older in 1996 with incident asthma between 1996 and 2009 who participated in the Canadian Community Health Survey were identified and followed until 2014 to determine the development of ACOS. Data on exposures to fine particulate matter (PM2.5) and ozone (O3) were obtained from fixed monitoring sites. Associations between air pollutants and ACOS were evaluated using Cox regression models.

MEASUREMENTS AND MAIN RESULTS:

Of the 6,040 adults with incident asthma who completed the Canadian Community Health Survey, 630 were identified as ACOS cases. Compared with those without ACOS, the ACOS population had later onset of asthma, higher proportion of mortality, and more frequent emergency department visits before COPD diagnosis. The adjusted hazard ratios of ACOS and cumulative exposures to PM2.5 (per 10 μg/m(3)) and O3 (per 10 ppb) were 2.78 (95% confidence interval, 1.62-4.78) and 1.31 (95% confidence interval, 0.71-2.39), respectively.

CONCLUSIONS:

Individuals exposed to higher levels of air pollution had nearly threefold greater odds of developing ACOS. Minimizing exposure to high levels of air pollution may decrease the risk of ACOS.

KEYWORDS:

air pollution; coexisting chronic disease morbidities; environmental exposures

PMID:
26950751
DOI:
10.1164/rccm.201510-1932OC
[Indexed for MEDLINE]

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