Johnson KM, et al. - Researchers investigated the extent of heterogeneity in symptoms and the factors related to this heterogeneity in patients with mild-to-moderate COPD. Participants included a sample of the general Canadian population ≥40 years with persistent airflow limitation followed for up to 3 years. During visits at 18-month intervals, participants were inquired about occurrence of chronic coughing, phlegm, wheezing, or dyspnea. Mixed-effect logistic regression models were used to assess heterogeneity. There were 968 visits by 449 participants (53% male, mean age 67 years), and 89% of patients reported at least one symptom during follow-up. Findings revealed a marked heterogeneity in the burden of respiratory symptoms between COPD patients. For wheeze and dyspnea, highest heterogeneity was noted. In addition, a difference was noted in the ability of lung function and other commonly measured clinical characteristics to explain this heterogeneity between symptoms.