Asthma and Chronic Obstructive Pulmonary Disease (COPD) are the two most common chronic lung diseases worldwide (1) and both involve a limitation of airflow through the airways and lungs (2). Asthma and COPD may develop through multiple pathways and manifest with some variation in symptomology and severity. The heterogeneity of asthma and COPD likely reflects the complex interactions of genetic, environmental and socio-cultural factors through which they are produced. Despite their similarities there are important distinctions in the underlying mechanisms and treatment of asthma and COPD (2).
What is Asthma?
Asthma is the chronic inflammation of the airways with episodic symptoms (exacerbations or flare-ups) in response to a variety of triggers. Triggers include allergens like dust and pollen, air pollutants such as constituents of tobacco and biomass smoke, vehicle exhaust, or even innocuous changes like physical exertion and cold air (3-4). The main symptoms of asthma are: shortness of breath, wheezing, coughing, and chest tightness (3, 5). Asthma is the most common non-communicable disease in children and affects over 335 million people worldwide (4), including an estimated 3.8 million Canadians 1 year and older (3). In Canada, the total cost for asthma treatment exceeded $2.2 billion in 2010, with projections of $4.2 billion by 2030 (6). The causes of asthma are only partially understood and cure is rare once the window of prevention is missed. Irreversible lung damage incurred during asthma exacerbations may lead to COPD later in life (1-2).
What is COPD?
COPD is a progressive, lung disease characterized by obstruction to exhaling air and loss of lung tissue (2). Unlike asthma, COPD typically appears in middle adulthood or later, with shortness of breath, coughing, and mucus production being the main symptoms. Acute exacerbations of COPD are life-threatening with COPD accounting for approximately 3 million deaths worldwide each year (1). Approximately 2 million Canadians 35 years and older have been diagnosed with COPD (3) which is the top medical condition causing hospitalizations in Canada (7). Hospitalizations due to COPD in Canada cost over $1.5 billion annually (8). COPD is caused primarily by inhaled toxicants. Tobacco smoke has historically been the major culprit (2) but pollution including that from fuel combustion both outdoor and indoor [burning of biomass (eg coal, dung, wood)] has now been recognized to cause more than 50% of COPD worldwide. Once prevention fails, COPD is currently an incurable disease.
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Under-diagnosis of asthma and COPD elevates the human and economic burdens of these diseases (2, 5). Early diagnosis and adherence to an evidence-based, personalised treatment, and self-management plan are currently the most effective ways of controlling asthma and COPD (1-2). In smokers with asthma and COPD, such plans include smoking cessation to slow the progression of lung damage and ameliorate symptoms (1-2). Indeed, without a cure for asthma and COPD, population-wide measures to reduce exposures to smoke and other air pollutants become indispensable to public health (2-3).
Forum of International Respiratory Societies, European Respiratory Society. The Global Impact of Respiratory Disease.; 2017.
Public Health Agency of Canada. Report from the Canadian Chronic Disease Surveillance System: Asthma and Chronic Obstructive Pulmonary Disease (Copd) in Canada, 2018. Public Health Agency of Canada; 2018. Accessed November 12, 2020. https://www.deslibris.ca/ID/10096543
Diette GB, Accinelli RA, Balmes JR, et al. Obstructive lung disease and exposure to burning biomass fuel in the indoor environment. Global Heart. 2012;7(3):265. doi:10.1016/j.gheart.2012.06.016
Mittmann N, Kuramoto L, Seung SJ, Haddon JM, Bradley-Kennedy C, FitzGerald JM. The cost of moderate and severe COPD exacerbations to the Canadian healthcare system. Respiratory Medicine. 2008;102(3):413-421. doi:10.1016/j.rmed.2007.10.010
Landrigen et al. The Lancet Commission on pollution and health. The Lancet 391:462-512. DOI: 10.1016/S0140-6736(17)32345-)