This study aimed to evaluate the association between the number of non-cystic fibrosis bronchiectasis (bronchiectasis) exacerbations during baseline and follow-up (objective 1) and to identify longitudinal changes in FEV₁ associated with exacerbation frequency (objective 2).

This was a retrospective cohort study of adult patients enrolled in the US Bronchiectasis and Nontuberculous Mycobacteria Research Registry September 2008 to March 2020. Objective 1 outcome was association between exacerbations during baseline (24 months) and 0-to-24 month and 24-to-48 month follow-up windows. Objective 2 outcomes were change in FEV₁ and FEV₁ % predicted over 24 months stratified by baseline exacerbation frequency.

Objective 1 cohort (N = 520) baseline frequency of any exacerbations was 59.2%. Overall, 71.4% and 75.0% of patients with ≥1 baseline exacerbations had ≥1 exacerbations during the 0-to-24 and 24-to-48 month follow-ups. Having ≥1 exacerbation during baseline was significantly associated with ≥1 exacerbation during the 0-to-24 month (P = 0.0085) and 24-to-48 month follow-ups (P=<0.0001). Objective 2 cohort (N = 431) baseline FEV₁ was significantly lower in patients who had more exacerbations; however, decline in FEV₁ from baseline was not significantly different between patients with 0, 1, and ≥2 exacerbations. In patients with more baseline exacerbations, FEV₁ % predicted was significantly lower at baseline (P < 0.0001) and at 12 (P = 0.0002) and 24 month follow-ups (P < 0.0001).

Patients with frequent bronchiectasis exacerbations may be more likely than those with less frequent exacerbations to experience disease progression based on future exacerbation frequency and lower FEV₁ at baseline, although FEV₁ decline may not differ by baseline exacerbation frequency.