The phenotype of concurrent chronic bronchitis and frequent exacerbations in patients with severe COPD attending Swedish secondary care units

BACKGROUND: Chronic bronchitis and previous exacerbations are both well-known risk factors for new exacerbations, impaired health-related quality of life, and increased mortality in COPD. The aim of the study was to characterize the phenotype of concurrent chronic bronchitis and frequent exacerbation in severe COPD. METHODS: Information on patient characteristics, comorbidity, and exacerbations from the previous year (total number and number requiring hospitalization) was collected from 373 patients with stage III and IV COPD attending 27 secondary care respiratory units in Sweden. Logistic regression used chronic bronchitis and frequent exacerbations (≥2 exacerbations or ≥1 hospitalized exacerbations in the previous year) as response variables. Stratification and interaction analyses examined effect modification by sex. RESULTS: Chronic bronchitis was associated with current smoking (adjusted odds ratio [OR] [95% CI], 2.75 [1.54–4.91]; P=0.001), frequent exacerbations (OR [95% CI], 1.93 [1.24–3.01]; P=0.004), and musculoskeletal symptoms (OR [95% CI], 1.74 [1.05–2.86]; P=0.031), while frequent exacerbations were associated with lung function (forced expiratory volume in 1 second as a percentage of predicted value [FEV(1)% pred]) (OR [95% CI] 0.96 [0.94–0.98]; P=0.001) and chronic bronchitis (OR [95% CI] 1.73 [1.11–2.68]; P=0.015). The phenotype with both chronic bronchitis and frequent exacerbations was associated with FEV(1)% pred (OR [95% CI] 0.95 [0.92–0.98]; P=0.002) and musculoskeletal symptoms (OR [95% CI] 2.55 [1.31–4.99]; P=0.006). The association of smoking with the phenotype of chronic bronchitis and exacerbations was stronger in women than in men (interaction, P=0.040). CONCLUSION: Musculoskeletal symptoms and low lung function are associated with the phenotype of combined chronic bronchitis and frequent exacerbations in severe COPD. In women, current smoking is of specific importance for this phenotype. This should be considered in clinical COPD care.