Characteristics of subjects susceptible to exacerbation-like respiratory events in a population-based cohort: Canadian cohort obstructive lung disease (CanCOLD) study

Rationale: There is no information on the characteristics of subjects sampled from the general population with mild to moderate COPD who are susceptible to exacerbation-like respiratory events. Objective: Assess in a population-based sample, if there are differences between the characteristics of subjects with COPD who report exacerbation-like events and those who do not. Methods: Canadian Cohort Obstructive Lung Disease (CanCOLD) is a longitudinal, multi-center study, 1400 subjects, ≥40 years old, identified by random digit dialling from the general population. Subjects are sex- and age-matched, and grouped:1) COPD moderate+ (GOLD≥2); 2) COPD mild (GOLD1); 3) at risk (ever smoker); 4) healthy (never smoker, no obstruction). An exacerbation questionnaire is administered at baseline and every 3 months to detect changes in respiratory symptoms, medication, work and health service use. Results: In a preliminary analysis of 372 subjects with COPD, 73 reported having an exacerbation-like event during a 6-month follow-up, 299 did not. Subjects who reported at least 1 event had greater BODE scores, a 2-fold increase in respiratory medication, and decreased lung function and health status. Smoking, MRC dyspnea score and co-morbidities were not associated with exacerbation events. Frequency of exacerbations increased with disease severity. Conclusions: From a population-sampling based cohort that mirrors the population of COPD patients at large,exacerbation-like respiratory events are associated with worsening disease manifestation in subjects with mild or moderate COPD. Longitudinal evaluation will allow for phenotype analysis.