Chronic bronchitis before age 50 years predicts incident airflow limitation and mortality risk

Background:Previous studies on the relationship of chronic bronchitis to incident airflow limitation and all-cause mortality have provided conflicting results, with positive findings reported mainly by studies that included populations of young adults. This study sought to determine whether having chronic cough and sputum production in the absence of airflow limitation is associated with onset of airflow limitation, all-cause mortality and serum levels of C-reactive protein (CRP) and interleukin-8 (IL-8), and whether subjects’ age influences these relationships.Methods:1412 participants in the long-term Tucson Epidemiological Study of Airway Obstructive Disease who at enrolment (1972–1973) were 21–80 years old and had FEV1/FVC (forced expiratory volume in 1 s/forced vital capacity) ⩾70% and no asthma were identified. Chronic bronchitis was defined as cough and phlegm production on most days for ⩾3 months in two or more consecutive years. Incidence of airflow limitation was defined as the first follow-up survey with FEV1/FVC