Prognostic Significance of Mild Exacerbations or One Moderate Exacerbation in COPD: A Prospective Community-Based Cohort Study.

Abstract

The association between frequent chronic obstructive pulmonary disease (COPD) exacerbations and poor respiratory health outcomes is well established, but the associations of only mild exacerbations and only one moderate exacerbation with prognosis remain controversial, especially among community participants with COPD. Are mild exacerbations and one moderate exacerbation associated with worse respiratory health outcomes in participants with COPD? We analyzed data from a multicenter, prospective, community-based cohort study. Moderate exacerbation was defined as new onset or worsening of respiratory symptoms requiring outpatient visit and antibiotic or oral corticosteroid treatment. Mild exacerbation was defined as new onset or worsening of respiratory symptoms requiring only home treatment with medications. The study outcomes included exacerbations and lung function decline over the 3-year follow-up. Of the 915 participants with COPD, 52 (6%) experienced frequent exacerbations, 45 (5%) experienced only one moderate exacerbation, 41 (4%) experienced only mild exacerbations, and 777 (85%) had no exacerbations in the previous year. Participants experiencing only mild exacerbations had severe emphysema, and participants experiencing only one moderate exacerbation had more severe air trapping than those without any exacerbations. Participants with mild exacerbations (rate ratio [RR]=1.67, 95% confidence interval [CI]: 1.11-2.51, P=0.014; RR=1.76, 95%CI: 1.13-2.73, P=0.012; respectively) or one moderate exacerbation (RR=1.89, 95%CI: 1.31-2.73, P<0.001; RR=2.29, 95%CI: 1.55-3.38, P<0.001; respectively) had higher incidence of total exacerbation and moderate-to-severe exacerbation than those without exacerbations. There was no significant difference in the annual rate of lung function decline among these participants. Among community-based participants with COPD, even with a low exacerbation burden, mild exacerbations and a single moderate exacerbation in the year prior to enrollment were associated with more severe computed tomography-defined lung structural abnormalities and a higher incidence of subsequent exacerbations over 3 years of follow-up.