10 Year Follow-up of Lung Function, Respiratory Symptoms, and Functional Capacity in the COPDGene Study.

RATIONALE The course of lung function, respiratory symptoms, and functional status over time in people who smoke cigarettes is still incompletely understood. The Genetic Epidemiology of COPD (COPDGene) study provides a unique cohort to examine these trajectories, and now 10 year follow-up data are available. OBJECTIVES This study aims to provide insight into the progression of spirometric parameters, respiratory symptoms, and functional capacity over 10 years in current and former cigarette smokers. METHODS We analyzed available longitudinal data for COPDGene participants who did not change smoking status over 3 visits spanning approximately 10 years of follow-up. Change in post-bronchodilator forced expiratory volume in one second (FEV1), St. George's Respiratory Questionnaire (SGRQ), and six-minute walk distance (6MWD) from Phase 1 to Phase 3 were examined using linear mixed models. Terms were included in the models to estimate mean progression separately for current and former cigarette smokers. Models were stratified by baseline GOLD spirometry stages as well as by new 2019 COPDGene Classification. RESULTS Mean age at enrollment of the 9,103 participants in this analysis was 59.8 years (SD=9.2 years); 46.4% were women, and 32.6% were African American. In all GOLD COPD groups, including participants with normal spirometry, as well as all groups categorized by 2019 COPDGene Classification, FEV1 decreased, SGRQ increased (indicating higher symptom burden), and 6MWD decreased over the 10 year follow-up period. Current smokers exhibited a greater mean loss of FEV1 over the study period than former smokers for all groups except those with preserved ratio impaired spirometry (PRISm). For both SGRQ and 6MWD, rates of progression tended to be similar for former and current smokers except for 6MWD in the highest severity groups, where former smokers had greater progression. However, this could be impacted by some current smokers with faster progression that had quit smoking and were dropped from analyses. CONCLUSIONS Progression in FEV1, SGRQ, and 6MWD overall appears to be slow, and the change over time in groups traditionally characterized as not having disease closely mirrors that of the groups with COPD at all GOLD stages. Current cigarette smokers had greater loss of FEV1 than former smokers, while SGRQ and 6MWD changes were more similar between current and former cigarette smokers.