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CanCOLD deepens our understanding of mild-to-moderate COPD and helps identify novel risk factors, reliable diagnostics for early detection of COPD, and helps us appropriately quantify COPD prevalence. Research using CanCOLD data advances clinical practice guidelines and health policies for the benefit of COPD patients.

Below are some of the key discoveries related to COPD that the CanCOLD study has facilitated.

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

What is known on the topic: Long-term exposure to outdoor air pollution has been linked to reduced lung growth in children, as well as lung function decline and increased risk of Chronic Obstructive Pulmonary Disease (COPD) in adults. Recent studies show that individuals with smaller airways relative to lung size also have a higher risk of developing COPD. Few studies on lung function (the ability of lungs to exchange gases) and COPD have been conducted in

areas with relatively low pollution concentrations, such as Canada. No study to date has examined the relationships between air pollution, lung structure, and lung function in adults.

What this study adds: 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 smaller airways 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

What is known on the topic: Chronic Obstructive Pulmonary Disease (COPD) exacerbations, or sudden symptom worsenings, are important indicators of the overall burden of COPD and contribute greatly to the increasing cost of the disease. These flare-ups are associated with accelerated decrease in breathing ability, impaired health status, increased risk of hospitalization, and increased

mortality. The frequency and impact of exacerbation events in individuals with undiagnosed COPD within the general population is unknown. The amount of hospital resources consumed as a result also remains unclear.

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

Granularity of SERPINA1 alleles by DNA sequencing in CanCOLD

What is known on the topic: Alpha-1 antitrypsin deficiency (AATD) is an inherited condition associated with an accelerated decrease in lung function, early onset emphysema and an increased risk of Chronic Obstructive Pulmonary Disease (COPD). The alpha-1 antitrypsin protein (AAT) is produced by the liver and released in the bloodstream to protect the lungs from damage. AATD is caused by genetic

mutations in the SERPINA1 gene that lead to abnormal or low production of the alpha-1 antitrypsin protein, thereby rendering the lungs vulnerable to damage. The type of mutation, whether rare or common, severe or mild, can be assessed through a method called DNA sequencing. Little is known about how common these genetic variants are in the Canadian population. Their individual and cumulative impacts on COPD characteristics such as lower lung function and emphysema also remains unknown.

What this study adds: This study shows that 15.5% of individuals of the CanCOLD cohort have at least one genetic mutation affecting AAT levels in the bloodstream. CanCOLD participants with variants resulting in severe AATD are more susceptible to develop airway obstruction. This study also shows the feasibility of using DNA sequencing on a large population to provide an accurate and definitive diagnosis for AATD. Results emphasize the advantages of this method, which include allowing clinicians to make more informed treatment decisions based on more personalized risk assessments and helping to reduce the under-diagnosis of AATD.

The effects of marijuana smoking on lung function in older people

What is known on the topic: Marijuana is the second most common substance smoked worldwide after tobacco, and the most common illicit drug used by the older population in the United States. Most studies have associated marijuana exposure with increased respiratory symptoms such as coughing or wheezing among long-term cannabis smokers. However, the long-term effects of marijuana

smoking on lung function, or the ability of lungs to exchange gases, remain unclear. Measuring lung function helps determine the risk of developing Chronic Obstructive Pulmonary Disease (COPD), a group of diseases that limit airflow due to inflammation.

What this study adds: This study reveals that the combined harmful effects of prolonged heavy tobacco and heavy marijuana smoking (over 20 pack-years and 20 joint-years respectively) 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

What is known on the topic: Individuals with COPD are at risk of reduced working hours, absenteeism, presenteeism and early retirement. Little attention has been given to the impact of COPD on work productivity loss, especially for those living with mild COPD and/or those who are yet to be diagnosed. This study measures work productivity loss via absenteeism, the health-related absence from

work, and/or presenteeism, the act of attending work while sick between individuals with mild to moderate COPD and those without COPD.

What this study adds: COPD patients with high symptom burden were shown to have an increased likelihood of experiencing work productivity loss, 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 hospitalizations and work-related outcomes by optimizing medication use, self-management interventions and pulmonary rehabilitation. This could further translate into the allocation of health management programs in the workplace.

Association of Dysanapsis With Chronic Obstructive Pulmonary Disease Among Older Adults

What is known on the topic: 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.