E-cigarette switching in COPD: reduced cardiovascular events without improvement in respiratory outcomes

Abstract

Background: The impact of switching to e-cigarettes in smokers after a chronic obstructive pulmonary disease (COPD) diagnosis on long-term health outcomes has not been widely evaluated. Methods: This nationwide cohort included 23,262 adults aged 40–80 years who were current smokers at the time of COPD diagnosis between 2016 and 2023. Based on follow-up health screening data, patients were categorized as continued smokers, quitters, or e-cigarette users (including dual users). The outcomes included lung cancer, COPD exacerbations, major adverse cardiac and cerebrovascular events (MACCE), and all-cause mortality. Adjusted hazard ratios (aHRs) with 95% confidence intervals (CIs) were estimated using Cox proportional hazards model. Results: Among 23,262 patients with COPD, 14,899 (64.0%) continued smoking, 7,047 (30.3%) quit, and 1,316 (5.7%) switched to e-cigarettes. During follow-up, quitters had significantly lower risks of lung cancer (adjusted HR [aHR], 0.85; 95% CI, 0.72–0.99), COPD exacerbations (aHR, 0.90; 95% CI, 0.84–0.97), MACCE (aHR, 0.85; 95% CI, 0.79–0.93), and all-cause mortality (aHR, 0.90; 95% CI, 0.82–0.99) compared with continued smokers. Switching to e-cigarettes was not associated with a lower risk of lung cancer (aHR, 0.94; 95% CI, 0.65–1.37) or COPD exacerbations (aHR, 0.98; 95% CI, 0.84–1.14) but was associated with a reduced risk of MACCE (aHR, 0.80; 95% CI, 0.66–0.97). Conclusions: Complete smoking cessation was associated with lower risks of lung cancer, COPD exacerbations, MACCE, and all-cause mortality. In contrast, switching to e-cigarettes was associated with a reduced risk of MACCE but did not provide comparable respiratory benefits. © The Author(s) 2026.