Characteristics of Current Smokers versus Former Smokers with COPD and Their Associations with Smoking Cessation Within 4.5 Years: Results from COSYCONET

Background: Many patients with chronic obstructive pulmonary disease (COPD) continue smoking. We used data from the real-life COSYCONET COPD cohort to evaluate whether these patients differed from patients with COPD who either had ceased smoking prior to inclusion or ceased during the follow-up time of the study.Methods: The analysis was based on data from visits 1-5 (covering 4.5 years), including all patients with the diagnosis of COPD who were either ex-smokers or smokers and categorized as GOLD 1-4 or the former GOLD 0 category. We compared the characteristics of smokers and ex-smokers at baseline (visit 1), as well as the course of lung function in the follow-up of permanent ex-smokers, permanent smokers and incident ex-smokers (smokers at visit 1 who ceased smoking before visit 5). We also identified baseline factors associated with subsequent smoking cessation.Results: Among 2500 patients who were ever-smokers, 660 were current smokers and 1840 ex-smokers at baseline. Smokers were younger than ex-smokers (mean 61.5 vs 66.0 y), had a longer duration of smoking but fewer pack-years, a lower frequency of asthma, higher forced expiratory volume in 1 sec (FEV1, 59.4 vs 55.2% predicted) and higher functional residual capacity (FRC, 147.7 vs 144.3% predicted). Similar results were obtained for the longitudinal subpopulation, comprising 713 permanent ex-smokers, 175 permanent smokers, and 55 incident ex-smokers. When analyzing the time course of lung function, higher FRC, lower FEV1 and the presence of asthma (p < 0.05 each) were associated with incident cessation prior to visit 5, while less airway obstruction was associated with smoking continuation.Conclusion: These findings, which were consistent in the cross-sectional and longitudinal analyses, suggest that lung hyperinflation was associated with being or becoming ex-smoker. Possibly, it is perceived by patients as one of the factors motivating their attempts to quit smoking, independent from airway obstruction.

Automated summary

This study based on the COSYCONET COPD cohort found that many patients with COPD continue smoking. Smokers were younger, had a longer duration of smoking but fewer pack-years, a lower frequency of asthma, and different lung function compared to ex-smokers. Lung hyperinflation was associated with being or becoming ex-smoker, possibly motivating patients to quit smoking independently of airway obstruction.