Association between ICS Use and Exacerbations in Bronchiectasis with Mycobacterial History

Background The role of inhaled corticosteroids (ICSs) in bronchiectasis is controversial, especially in patients with prior tuberculosis or nontuberculous mycobacterial infection. This study aimed to examine the association between ICS use and the risk of acute exacerbations (AEs) in this population. Methods We analysed 370 patients with bronchiectasis and prior mycobacterial infection from the Korean Multicentre Bronchiectasis Audit and Research Collaboration (KMBARC) registry. Patients were classified by ICS use at enrolment. The primary outcome was the annual rate of any AEs; secondary outcomes were severe AEs and mortality. Associations between ICS use and AE rates were evaluated using negative binomial regression adjusted for confounders. Results The rate of any AEs was higher in ICS users (n=62, 16.8%) than in non-users (n=308, 83.2%, 43.01 versus 27.81 events per 100 person-years, p=0.036). In multivariable analysis, ICS use was associated with a higher rate of any AEs (adjusted IRR 1.91, 95% CI 1.08–3.41, p=0.027). For severe AEs, rates were 12.37 versus 9.63 events per 100 person-years (p=0.687); the adjusted IRR was 1.48 (95% CI, 0.52–4.20; p=0.458), showing a similar but non-significant trend. Mortality rates were comparable between groups (1.08 versus 0.97 deaths per 100 person-years, p=0.525). Subgroup analyses showed a consistent trend toward higher AE rates with ICS use, regardless of eosinophil count, prior AE frequency, or asthma. Conclusions ICS use was associated with a higher risk of AEs in patients with bronchiectasis and prior mycobacterial infection, warranting caution.