Relationship between airway inflammation, small airway dysfunction, and frequency of acute exacerbations in patients with chronic obstructive pulmonary disease

Context

Recurrent exacerbations in COPD patients are associated with accelerated reduction in lung function. Airway inflammation and small airway dysfunction were recognized for a long time as an essential feature of COPD.

Aim

To study the relationship between neutrophilic airway inflammation, small airway dysfunction, and frequency of acute exacerbations in COPD patients.

Settings and design

This was a cross-sectional study.

Patients and methods

Thirty COPD patients were enrolled and classified into two groups: infrequent exacerbators (IFE) “who developed ≤ 1 exacerbation per year” and frequent exacerbators (FE) “who developed ≥ 2 exacerbations per year” in the last year prior to this study. All patients included in the study underwent clinical evaluation, and assessment of small airway dysfunction by pulmonary function testing (MEF 25–75, RV/TLC, and DLCO) and paired inspiratory and expiratory HRCT-chest to measure the mean lung density (MLD) as well as assessment of neutrophilic airway inflammation by taking BAL via bronchoscopy and examined for differential cell count.

Results

The small airway dysfunction is more severe in the case of the FE COPD group as there were statistically significant differences between FE and IFE COPD groups in %MEF 25–75 and RV/TLC (p = 0.038 and p = 0.030, respectively). The mean value of the BAL neutrophil % was higher in FE than in IFE COPD patients but without a significant statistical difference (p = 0.513). There were statistically significant negative correlations between %FEV1 (p = 0.026), %FVC (p = 0.020), and %MEF25–75 (p = 0.005) and MLD(E/I) in all studied COPD patients.

Conclusion

COPD patients associated with small airway dysfunction and increased BAL neutrophil cell count are more prone to frequent exacerbations.

Trial registration

ClinicalTrials.gov NCT06040931. Registered 18 Sept 2023—Retrospectively registered.