Bronchiectasis, Exacerbation Indices, and Inflammation in Chronic Obstructive Pulmonary Disease

TLDR

The link between HRCT findings in COPD and bacterial colonization, airway inflammation, or exacerbation indices is not yet established. The study assessed 54 COPD patients with HRCT to quantify bronchiectasis or emphysema, recorded exacerbation indices from 2‑year diary cards, and performed quantitative sputum bacteriology and cytokine analyses. Half of the patients had lower‑lobe bronchiectasis, which correlated with higher airway inflammatory cytokines, increased sputum IL‑8, lower airway bacterial colonization, and prolonged recovery from exacerbations, although exacerbation frequency was not linked to HRCT changes.

Abstract

Relationships between high-resolution computed tomography (HRCT) findings in chronic obstructive pulmonary disease (COPD) and bacterial colonization, airway inflammation, or exacerbation indices are unknown. Fifty-four patients with COPD (mean [SD]: age, 69 [7] years; FEV(1), 0.96 [0.33] L; FEV(1) [percent predicted], 38.1 [13.9]%; FEV(1)/forced vital capacity [percent predicted], 40.9 [11.8]%; arterial partial pressure of oxygen, 8.77 [1.11] kPa; history of smoking, 50.5 [33.5] smoking pack-years) underwent HRCT scans of the chest to quantify the presence and extent of bronchiectasis or emphysema. Exacerbation indices were determined from diary cards over 2 years. Quantitative sputum bacteriology and cytokine measurements were performed. Twenty-seven of 54 patients (50%) had bronchiectasis on HRCT, most frequently in the lower lobes (18 of 54, 33.3%). Patients with bronchiectasis had higher levels of airway inflammatory cytokines (p = 0.001). Lower lobe bronchiectasis was associated with lower airway bacterial colonization (p = 0.004), higher sputum interleukin-8 levels (p = 0.001), and longer symptom recovery time at exacerbation (p = 0.001). No relationship was seen between exacerbation frequency and HRCT changes. Evidence of moderate lower lobe bronchiectasis on HRCT is common in COPD and is associated with more severe COPD exacerbations, lower airway bacterial colonization, and increased sputum inflammatory markers.