Overview (S-000098)
Chronic Obstructive Pulmonary disease (COPD) is a common and serious chronic respiratory disease. Exacerbations of COPD (ECOPDs) are characterized by a sudden worsening of symptoms. The frequency and severity of ECOPDs are associated with higher mortality and carry a significant burden on patients as well as on health systems. The GOLD 2023 ECOPD definition reflects an increasing appreciation of the role of air pollution as a possible exacerbation trigger. The Spring of 2020 was associated with national lockdowns in Canada and around the world in response to the COVID-19 pandemic. The secondary effects on air pollution concentrations during, before and after this period provide a unique opportunity to better understand the association between ambient air pollution concentration and exacerbation frequency, as well as the individual-level risk factors which may affect this association. Objectives: To evaluate ambient air pollution concentration changes in 9 Canadian cities during the COVID-19 pandemic in comparison with the ‘pre-COVID’ and ‘Post-COVID’ periods and their relationship with exacerbation rates among patients with COPD followed in the Canadian cohort obstructive lung disease (CanCOLD) study to determine individual-level risk factors associated with exacerbations around relatively higher air pollutant concentration periods. Methods: Information on baseline demographic/characteristics, spirometry results, blood eosinophil count, and exacerbations (both ‘symptom based’: ≥48 hours of dyspnea/sputum volume/purulence; ‘event based’: ‘symptom based’ plus requiring antibiotics/corticosteroids or healthcare use) will be collected from CanCOLD participants. Data from the CanCOLD ‘COVID-19 Questionnaire’ will also be obtained. The National Air Pollution Surveillance (NAPS) program database will be used to estimate monthly air pollution exposure concentration. Hourly records of fine particulate matter (PM2.5), nitrogen dioxide (NO2), and ozone (O3) over each defined study period will be obtained. Monthly temperature and relative humidity will also be retrieved from open-access databases. Variations in air pollution concentration, variations in monthly exacerbation rates, and the association between these in CanCOLD participants with fixed airflow obstruction will be estimated across pre-lockdown, lockdown, and post-lockdown periods by fitting Poisson regression models with GEE. The effect of individual-level factors (blood eosinophil count, co-morbid asthma, gender, and CANUE-derived socioeconomic neighbourhood status) on these associations will be investigated in separate models. Expected Outcomes and Significance: We hypothesize that the pan-Canadian COVID-19 lockdown period in the Spring of 2020 will be characterized by both significant reductions in monthly NO2 and PM2.5 concentrations and by significant reductions in the rate of monthly exacerbations. Moreover, we postulate that monthly NO2 and PM2.5 exposure will be positively associated with monthly exacerbation rates, even following adjustment for relevant confounders. Finally, we hypothesize that the presence of physician-diagnosed co-morbid asthma, higher peripheral eosinophil level, living in a lower socioeconomic neighbourhood, and female gender may each be associated with more frequent exacerbations of COPD during relatively higher air pollutant concentration periods. This study may inform future ECOPD prevention measures, for example by identifying novel/emerging ‘biomarkers’ for air pollution-associated exacerbation risk such as the blood eosinophil count, or by guiding public health interventions specifically targeting higher-risk demographic groups during periods with transient increases in air pollutant concentration.
Calendar
- Application Date
- 2023-06-05
- Approval Date
- 2023-06-27
Contact Details
- Name
- Dr Bryan Ross
- Institution
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McGill University Health Centre (MUHC) Note: DAR#121459