, according to the authors of a retrospective study in the Journal of Allergy and Clinical Immunology: In Practice. While bronchiectasis is known to worsen the clinical and functional outcomes in patients with asthma, data regarding the long-term effects of bronchiectasis on the clinical course of asthma have been limited, stated corresponding author Jung-Kyu Lee, MD, division of pulmonary and critical care medicine, Seoul (Republic of Korea) Metropolitan Government – Seoul National University.
Moderate to severe acute clinical deterioration risks were increased among the 251 patients (mean age 66.6 years, 77.2% men) with bronchiectasis out of 667 asthma patients included in the study. All studied patients underwent chest computed tomography and pulmonary function tests from 2013 to 2019 at two tertiary hospitals in Seoul. The primary outcome, annual incidence of moderate to severe acute exacerbations requiring additional treatment (systemic steroids, antibiotics, or both), was significantly higher in patients with bronchiectasis after a mean follow-up period of 3.96 years. Compared with patients who did not exhibit bronchiectasis, the annual rates of severe exacerbations (0.15 ± 0.43 vs. 0.08 ± 0.27; P = .010), moderate to severe (0.47 ± 0.79 vs. 0.34 ± 0.63; P = .018), and acute exacerbations during the follow-up period (49.8% vs. 39.4%; P = .009) were all significantly higher. There was no difference in the proportion of frequent exacerbators between the two groups, however. Severe acute exacerbations leading to hospitalizations, also, were more frequent in the group with bronchiectasis.
Risk factors explored
Significant factors conferring greater risk of severe and moderate to severe acute exacerbations in multivariable analysis included low body mass index, low baseline forced expiratory volume in 1 second (FEV1), high use of inhaled corticosteroids, high medication possession, and high neutrophil/lymphocyte ratios. The existence of bronchiectasis remained an independent risk factor for severe and moderate to severe acute exacerbations despite adjustment for all other factors. While bronchiectasis score showed no association with annual rate of acute exacerbation, progression of bronchiectasis confirmed on follow-up CT was associated with increased risks of severe and moderate to severe acute exacerbation.
Included patients had a diagnosis of asthma confirmed by variable expiratory airflow limitation with pulmonary function tests (that is, positive bronchodilator response, positive bronchial provocation test, or excessive variation in lung function between visits). Past histories of tuberculosis and nontuberculous mycobacterial lung disease, lower absolute and predicted values of both baseline FEV1 and forced vital capacity were more common among patients with bronchiectasis.
Dividing the study population into a group that had at least one moderate to severe acute exacerbation during the follow-up period and a group that did not, the researchers identified characteristics shared by exacerbators: a greater proportion were women, they had lower forced vital capacity and lung-diffusing capacity for carbon monoxide, higher blood FVC and blood neutrophil/lymphocyte ratio, and more medication use (inhaled corticosteroids, long-acting antimuscarinic agent, leukotriene-receptor antagonist, and methylxanthine), compared with the nonexacerbators. More bronchiectasis, more severe bronchiectasis (higher bronchiectasis score), and more progression of bronchiectasis were common among the exacerbators.
Higher acute exacerbation risks accompanied bronchiectasis, at 1.47-fold for moderate, 1.72-fold for severe, and 1.50-fold for moderate to severe exacerbations. Higher risk for severe and moderate to severe exacerbations was conferred by bronchiectasis progression, also.
The researchers pointed to contradictory effects of inhaled corticosteroid use, noting both corticosteroids’ essential role in controlling airway inflammation and hyperresponsiveness, exacerbations, and lung-function decline in asthma patients and that longer or greater inhaled corticosteroid use is associated with both clinical deterioration in asthma and bronchiectasis, and exacerbation history. For bronchiectasis, however, inhaled corticosteroid use offers no benefit while increasing susceptibility to infection and its risks through partial immunosuppression.
“Considering these contradictory effects of inhaled corticosteroid use, further research is needed regarding its risks and benefits in asthma patients with bronchiectasis, including differences in the benefit of inhaled corticosteroid use according to patient phenotype,” Dr. Kim and his colleagues concluded.