Frequency and severity of exacerbations reflect COPD severity, but not COPD phenotype as determined by quantitative CT

Abstract

COPD exacerbations worsen lung function, quality of life and prognosis. We investigated the relationship between characteristics of COPD exacerbations and lung pathologic changes as assessed by quantitative CT.

133 COPD outpatients underwent clinical examination, whole pulmonary function and CT scan. Frequency, severity and clinical presentation of exacerbations occurring within the year prior to visit were collected by standardized questionnaire. Hospitalization or access to emergency department indicated more severe events. We considered "frequent exacerbators" patients with ≥2 episodes/year and distinguished exacerbations with only dyspnea and only sputum from those with both symptoms. From original CT scan values of parenchymal destruction (%LAA-950) and airway wall thickness (AWT-Pi10) we derived by principal component analysis two novel parameters, CT1 and CT2, which are the expression of COPD phenotype and severity, respectively (ERJ 2013;42:626-635). Phenotypic characteristics range progressively from airway predominant (CT1-) to emphysema predominant (CT1+). Severity of disease increases progressively from CT2- to CT2+.

Characteristics, frequency and severity of exacerbations did not differ between patients with predominant airway disease (CT1-) and those with predominant emphysema (CT1+). Patients with more severe lung CT changes (CT2+), more severely impaired function, and higher BODE score had more frequent and severe exacerbations. In conclusion, frequency and severity of exacerbations could be a reliable index of COPD severity, but not of the predominant pathophysiologic mechanism of airflow limitation as determined by CT quantitative analysis.