Association between chronic bronchitis (CB+) and forced expiratory volume in 1 s (FEV1) decline

Model 1Model 2
β (95% CI)p-valueβ (95% CI)p-value
Subjects n270259
COPD CB+−35.2 (−57.9–−12.5)0.002−38.2 (−61.7–−14.6)0.002
Male COPD CB+−42.8 (−77.3–−8.2)0.016−42.8 (−78.1–−7.6)0.018
Female COPD CB+−29.4 (−58.7–−0.05)0.050−36.1 (−67.1–−5.2)0.022

Annual lung function decline (mL·year-1) was calculated by dividing the difference between two FEV1 measurements by the number of years between the two measurements. β-values represent the additional decline of FEV1 in chronic obstructive pulmonary disease (COPD) CB+ subjects compared to COPD subjects without chronic bronchitis. Model 1: age and sex# adjusted; model 2: adjusted for age, sex# and pack-years of cigarette smoking. #: unstratified analyses only.