Chronic bronchitis is a condition characterized by the inflammation and irritation of bronchial tubes. The condition is often associated with long-term cigarette smoking among young adults. However, the health outcomes of nonobstructive chronic bronchitis remain uncertain. This study aims to examine the adverse health outcomes associated with nonobstructive chronic bronchitis is ever smokers and never smokers.

In this prospective cohort study, a total of 22,325 adults without initial airflow obstruction or asthma at baseline were included. The health outcomes of patients with nonobstructive chronic bronchitis were identified. The primary outcome of the study was lung function among patients with nonobstructive chronic bronchitis.

Out of 22,325 participants, 11,082(49.6%) were ever smokers. During 99,869 years of follow-up with ever smokers, participants with nonobstructive chronic bronchitis (300) had higher declines in FEV1 levels, increased risk of chronic lower respiratory disease, higher respiratory disease-related mortality, and all-cause mortality, as compared with ever smokers without nonobstructive chronic bronchitis. Among 11,243 never smokers and 120,004 person-years of follow-up, participants with nonobstructive chronic bronchitis (151) had increased rates of chronic lower respiratory disease and mortality, as compared with never smokers without nonobstructive chronic bronchitis.

The research concluded that nonobstructive chronic bronchitis in both ever and never smokers was associated with an increased risk of adverse respiratory health outcomes.