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Découvertes

Nos Principales Découvertes

CanCOLD approfondit notre compréhension de la MPOC légère à modérée et aide à identifier de nouveaux facteurs de risque, des diagnostics fiables pour la détection précoce de la MPOC, et nous aide à quantifier de manière appropriée la prévalence de la MPOC. La recherche utilisant les données de CanCOLD fait progresser les guides de pratique clinique et les politiques de santé au profit des patients atteints de MPOC.

Ci-dessous figurent certaines des principales découvertes liées à la MPOC que l’étude CanCOLD a permis de réaliser.

Ambient Air Pollution and Dysanapsis: Associations with Lung Function and COPD in the CanCOLD Study

Background: Long-term exposure to ambient air pollution has been linked to reduced lung function growth in children, as well as lung function decline and increased chronic obstructive pulmonary disease (COPD) prevalence and incidence in adults. Recent studies show that a mismatch between airway tree calibre and lung size (i.e., dysanaptic lungs) is associated with a higher risk of COPD, even among individuals who have never smoked. Few studies

of the impact of air pollution exposure on lung function and COPD have been conducted in locations with relatively low pollution levels such as Canada, and little is known on how host factors such as developmental abnormalities of airways and lung growth affect the relationship between air pollution and lung health.

What this study adds: This is the first study in Canada to examine associations of long-term ambient air pollution exposure with lung function and spirometrically-confirmed COPD. This study shows statistically and clinically significant effects of ambient air pollution exposure on lung function, even at low concentrations compared to many countries around the world. For the first time, this study also shows that individuals with dysanaptic lungs may be more susceptible to the long-term effects of air pollution exposure on lung function and COPD.

Undiagnosed Chronic Obstructive Pulmonary Disease Contributes to the Burden of Health Care Use

Background: Chronic obstructive pulmonary disease (COPD) exacerbations represent an important determinant of the overall burden of COPD and contribute greatly to the increasing cost of the disease. These episodes of acute symptom worsening are associated with accelerated lung function decline, impaired health status, increased hospitalization, and increased mortality. The incidence and impact of exacerbation events in persons with undiagnosed COPD within

the general population is unknown.

What this study adds: This study shows for the first time that despite experiencing fewer exacerbations, health care use to treat exacerbation-like events in undiagnosed individuals with COPD is similar to that of diagnosed individuals. Consequently, COPD exacerbation events contribute much more than previously thought to the overall burden of COPD. Considering that a significant number of people remain undiagnosed with COPD, the exacerbation-like events they experience are being treated as isolated incidences without awareness of the need for future management of underlying COPD.

Granularity of SERPINA1 alleles by DNA sequencing in CanCOLD

Background: Alpha-1 antitrypsin (AAT) deficiency (AATD) is an inherited condition characterized by low AAT serum concentrations and is associated with an accelerated rate of lung function decline, early onset emphysema and an increased risk of Chronic Obstructive Pulmonary Disease (COPD). AATD is caused by genetic mutations in the SERPINA1 gene. DNA sequencing provides a complete assessment of the mutated gene by detecting its

conventional mutated alleles and its rare and novel genetic variants. Little is known about how common these deficient alleles are in the Canadian population and their individual and cumulative impacts on COPD phenotypes including lung function decline and emphysema.

What this study adds: This study shows that 15.5% of individuals of the CanCOLD cohort were carriers of at least one deficient allele affecting AAT serum levels. CanCOLD participants with genotypes resulting in severe AATD were more susceptible to develop airway obstruction, as demonstrated by lower lung function and greater emphysema. This study also shows the feasibility of DNA sequencing on a large scale to provide an accurate and definitive diagnosis for AATD. Results emphasize the advantages of genotype screening, which include allowing clinicians to make more informed treatment decisions based on more personalized risk prediction and helping to reduce the reported under-diagnosing of alpha-1-antitrypsin deficiency.

The effects of marijuana smoking on lung function in older people

Background: Marijuana is the second most common substance smoked worldwide after tobacco. Previous studies have associated marijuana exposure with increased respiratory symptoms and chronic bronchitis among long-term cannabis smokers. However, the long-term effects of marijuana smoking on lung function remain unclear.

What this study adds: This study reveals that the combined harmful effects of prolonged heavy tobacco and heavy marijuana smoking increases the risk of COPD and accelerates FEV1 decline (lung function) beyond the effects of tobacco alone. These results address a major gap in marijuana research by demonstrating that marijuana smoking amplifies the harmful effects of tobacco smoking on risk of COPD and lung function decline over time.

Work productivity loss in mild to moderate COPD, lessons learned from the CanCOLD study

Background: The impact of Chronic Obstructive Pulmonary Disease (COPD) on overall quality of life goes beyond the physical and mental strain it represents as the disease has an important economic impact on individuals and society. Little attention has been given to the impact of COPD on work productivity loss.

What this study adds: COPD patients with high symptom burden were shown to have an increased likelihood of experiencing work productivity loss (i.e. absenteeism and/or presenteeism), even among individuals with mild to moderate COPD. This study thereby shows that the burden of COPD goes beyond its impact on the health care system. Strategies to reduce the societal burden of COPD should include those that prevent both hospitalisations and work-related outcomes by optimizing medication use, self-management interventions and pulmonary rehabilitation.

Association of Dysanapsis With Chronic Obstructive Pulmonary Disease Among Older Adults

Background: Chronic Obstructive Pulmonary Disease (COPD) develops in some people but not others. Tobacco smoking is a well-known risk factor for COPD, but only a minority of smokers develop COPD, and COPD is not uncommon among never smokers. This study investigated whether the way lung develops might be an important contributor to COPD later in life.

What this study adds: This study found that a mismatch between airway tree and lung size is quite common in the general population. It also found that people with smaller airway tree relative to lung size were at much higher risk of developing COPD later in life. These findings suggest that lung development plays an important role in whether someone will develop COPD or not.