The Canadian Lung Outcomes in Users of Vaping Devices Study

The Canadian Lung Outcomes in Users of Vaping Devices (CLOUD) Study

Vaping is increasingly popular with both adolescent and adult Canadians, but the long-term health impacts remain unknown. We believe that the tools we currently have to detect lung disease in people who vape may be insufficient and propose new ways to find lung injuries that may impact them over the course of their lives. These include exercise testing, new imaging techniques, and new breathing tests that will demonstrate how vaping may harm their lungs. We will use these tools in both adolescent and adult Canadians to give Canadians who vape important information on the consequences of vaping.

Promoted as a safer method of inhaling nicotine compared to cigarettes and as smoking cessation tools, e-cigarettes have substantially grown in popularity with rates of uptake now exceeding those of cigarette smoking. In Canada, 6% of Canadians aged 15 years and older have vaped in the past 30 days. Younger Canadians appear to be the most susceptible to these habits, with 14% of those aged 15-19 years and 18% of those aged 20-24 years reporting past 30 day use. Indigenous populations are also disproportionately affected by the spread of vaping which may place them at higher risk for potential downstream respiratory complications. As Canadians increasingly reach for e-cigarettes, especially at younger ages and not just for the purposes of smoking cessation, greater clarity into the pulmonary toxicities vaping is urgently needed.

The Canadian Lung Outcomes in Users of Vaping Devices (CLOUD) Study is a pan-Canadian, multicentre, multidisciplinary, and longitudinal approach to studying vaping from cell to society. The characterization of e-cigarettes' respiratory effects remains superficial and a more comprehensive phenotyping of vaping-exposed lungs across the lifespan using novel imaging and pulmonary function techniques, dynamic exercise testing, and airway cell sequencing would significantly enhance our understanding of the potential harms. As with combustible cigarette smoking, the small airways (characterized by a diameter <2mm) may be particularly vulnerable during vaping given their high degree of exposure to particulate matter. These regions of the lung may harbour the earliest signs of injury, ultimately setting the stage for future obstructive airways disease.

Objectives

The objective of the CLOUD Study is to characterize small airway injury in adolescent and adult Canadians who use e-cigarettes. Specifically, our goals are to:

1. Characterize the structural and functional disruptions associated with e-cigarette use using oscillometry, multiple breath washout, chest computed tomography, hyperpolarized 129-xenon magnetic resonance imaging, cardiopulmonary exercise testing, and bronchoscopy.
2. Determine the association between e-cigarette use and respiratory outcomes, including symptom burdens, exacerbation-like respiratory events, and school and work absences.
3. Characterize the epigenetic and transcriptomic disruptions associated with e-cigarette use in blood, sputum, airway epithelium, and lung immune cells.

Methods Our observational, longitudinal cohort study encompasses six academic hospital centres across Canada (the University of British Columbia, the University of Alberta, McMaster University, the University of Ottawa, the University of Toronto, and the Université de Sherbrooke). Participants (n=100 ages >12 and <19 years and n=400 ages ≥19 years) will be followed over 3 years, undergoing repeat demographic and respiratory symptom questionnaires, oscillometry, pulmonary function testing, and exercise testing. Adolescent participants will additionally undergo multiple breath washout and induced sputum collection and adult participants will undergo chest CT imaging and bronchoscopy. A substudy of adolescent and adult participants undergoing pulmonary hyperpolarized 129-xenon gas magnetic resonance imaging will also be performed. Induced sputum and bronchoscopy-derived airway epithelial and bronchoalveolar lavage samples will be sequenced for methylation and transcriptomics.

Inclusion Criteria:

Adolescent arm:

• Aged ≥12 and <19 years old
• Either 1) use neither combustible cigarettes nor e-cigarettes or 2) use e-cigarettes exclusively

Adult arm:

• Aged ≥19 years old
• Fall into one of the following categories: 1) use neither combustible cigarettes nor e-cigarettes; 2) use combustible cigarettes exclusively, never using e-cigarettes; 3) use e-cigarettes exclusively, never using combustible cigarettes; or 4) use both combustible cigarettes and e-cigarettes currently

Exclusion Criteria:

Adolescent arm:

• Contraindication to pulmonary function testing and cardiopulmonary exercise testing
• Have smoked combustible cannabis within the last month and/or have a combustible cannabis smoking history of >1 joint-year
• Have smoked combustible cigarettes within the last 6 months
• Have a physician-diagnosed chronic lung disease (such as asthma, cystic fibrosis, or bronchopulmonary dysplasia)
• Inability to provide written informed consent

Adult arm:

• Contraindication to pulmonary function testing and cardiopulmonary exercise testing
• Have smoked combustible cannabis within the last month and/or have a combustible cannabis smoking history of >1 joint-year
• Currently undergoing treatment for lung cancer
• Inability to provide written informed consent

No limitations will be placed on the type of e-liquids used by participants; e.g., e-cigarette users of nicotine, tetrahydrocannabinol, and cannabidiol will be all enrolled.