Setting: Frequent exacerbation is an important phenotype in chronic obstructive pulmonary disease (COPD), while emphysema is associated with many comorbidities and lung function decline.
Objective: To investigate unique features of frequent exacerbators and test the hypothesis that emphysematous phenotype is associated with frequent exacerbations of COPD.
Methods: A total of 380 COPD patients were recruited from 16 hospitals in Korea from June 2005 to April 2012 for analysis. We searched for independent predictors of frequent exacerbators in comparison with non-exacerbators.
Results: As the severity of emphysema increased, forced expiratory volume in 1 s (FEV₁), and FEV₁/FVC (forced volume capacity) worsened; hyperinflationary features characterised by higher total lung capacity (TLC) were observed (P < 0.05). Frequent exacerbators had lower body mass index (BMI), higher St George's Respiratory Questionnaire (SGRQ) scores, higher residual volume (RV)/TLC, more severe airflow limitation (lower FEV₁ and FEV₁/FVC), lower carbon monoxide diffusion capacity, lower serum protein levels and a higher emphysema index than non-exacerbators (P < 0.05). In multivariate analysis, frequent exacerbators were independently associated with a higher emphysema index, lower serum protein levels and higher RV/TLC (P < 0.05).
Conclusion: Our data show that the severity of emphysema, severe static hyperinflation and serum lower protein levels are independent predictors of frequent exacerbations in COPD patients.