Impact of bronchitis variability on outcomes of COPD.

Objective: This study aimed to evaluate the impact of serial bronchitic status over two consecutive years on clinical outcomes, including frequency of exacerbation and lung function decline rate.

Methods: We analysed data from 1265 participants enrolled in the Korea COPD Subgroup Study, a nationwide prospective observational chronic obstructive pulmonary disease (COPD) cohort. Bronchitic status was determined using subquestionnaires of the COPD Assessment Test at baseline and after 1 year, classifying patients into three serial bronchitic groups of persistently not bronchitic (NB), intermittently bronchitic (IB) and chronic bronchitis (CB). Annualised exacerbation rates and longitudinal lung function decline rates were analysed.

Results: The NB group consisted of 873 individuals, the IB group contained 272 and the CB group included 120. The analysis of baseline demographics showed a greater prevalence of current smokers in the CB and IB groups compared with the NB group. Patients with CB exhibited the worst baseline symptoms and lung function, while those with IB had worse clinical features compared with those with persistently NB. Patients with CB had the highest rate of moderate-to-severe exacerbations, followed by IB, compared with persistently NB. No significant differences in forced expiratory volume in 1 s or forced vital capacity decline rates were observed among the groups.

Conclusions: Patients with CB and IB exhibit a greater risk of exacerbations than those with NB, whereas lung function decline rates did not significantly differ between groups.