Long-Term Effects of Bronchiectasis on Clinical Course of Asthma

The presence and progression of bronchiectasis are associated with greater risk for moderate to severe acute clinical deterioration among patients with asthma, according to study results recently published in The Journal of Allergy and Clinical Immunology: In Practice.

The effects of bronchiectasis on the clinical course of asthma has been unclear. To clarify this relationship, study authors conducted a retrospective study to evaluate longitudinal clinical outcomes of patients with asthma according to bronchiectasis status at 2 tertiary care hospitals in South Korea between January 1, 2013, and December 31, 2019.

Study inclusion criteria were (1) diagnosis of asthma confirmed by variable expiratory flow limitation with pulmonary function tests (PFTs); (2) radiologic assessment with at least 1 chest computed tomography (CT) scan; and (3) at least 2 pulmonary function tests during the follow-up period. The spirometric criteria for asthma were in accordance with the definition of the Global Initiative for Asthma (GINA) in place at the time of the analysis. In each patient, the Charlson Comorbidity Index was calculated to estimate the severity of all underlying comorbidities.

The primary study outcome was annual incidence of moderate to severe acute exacerbations in patients with asthma — with or without bronchiectasis. The Investigators defined an exacerbation as “an episode characterized by changes from the patient’s previous status, which required additional treatment.”

Bronchiectasis was diagnosed per chest CT scan as follows: (1) lack of bronchial tapering; (2) bronchial dilation when the internal diameter was larger than the diameter of the adjacent pulmonary artery; or (3) visualization of peripheral bronchi within 1 cm of the costal pleural surface or adjacent mediastinal pleural surface. The annual incidence of episodes of moderate to severe acute clinical deterioration (ie, exacerbations) and longitudinal changes in lung function were assessed.

A total of 667 patients with asthma were included in the study, 37.6% (251 of 667) of whom had bronchiectasis and 62.4% (416 of 667) of whom did not have bronchiectasis. Overall, 77.2% of the participants were men. The mean patient age was 66.6 years, and the mean follow-up time was 3.96 years.

Those participants with bronchiectasis had a significantly increased prior history of tuberculosis and non-TB mycobacterial lung disease, as well as lower absolute and predicted values of baseline forced expiratory volume in 1 second (FEV₁) and forced vital capacity (FVC) than did those without bronchiectasis. Additionally, although the cohort with bronchiectasis included a higher percentage of never-smokers compared with the cohort without bronchiectasis, no difference was reported in the smoking intensity (as measured by pack/years) according to bronchiectasis status.

Results of the study showed that patients with bronchiectasis vs those without the condition exhibited significantly higher annual rates of severe acute exacerbations (0.15±0.43 vs 0.08±0.27, respectively; P =.010), as well as higher annual rates of moderate to severe acute exacerbations (0.47±0.79 s 0.34±0.63, respectively; P =.018). Further, the group with bronchiectasis included a greater proportion of patients who experienced acute exacerbations during the follow-up period vs with those without bronchiectasis (49.8% vs 39.4%, respectively; P =.009).

The current analysis has several limitations. Because it was a retrospective cohort study, the level of evidence was moderate. Additionally, the patients evaluated in this study were undergoing chest CT and PFTs while receiving active treatment at tertiary hospitals, which might have led to selection bias.

Overall, although the presence and progression of bronchiectasis were associated with an increased risk for moderate to severe acute exacerbations of asthma, these factors were not related to longitudinal changes in pulmonary function, said study authors. Nevertheless, they added, “This study suggests that it is necessary to evaluate the presence and severity of bronchiectasis in asthma patients with frequent clinical deteriorations.”

Reference  

Kim NY, Lee CH, Jin KN, et al. Clinical deterioration and lung function change in patients with concomitant asthma and bronchiectasis. J Allergy Clin Immunol Pract. Published online June 8, 2022. doi:10.1016/j.jaip.2022.05.026