Association between current e-cigarette use and chronic obstructive pulmonary disease: a meta-analysis focusing on exclusive e-cigarette users

Background: While often promoted as a safer alternative to traditional cigarettes, electronic cigarettes (e-cigarettes) are linked to uncertain long-term health effects. Their independent relationship with chronic obstructive pulmonary disease (COPD) remains unclear, mainly due to the confounding effects of traditional cigarette use. This meta-analysis aimed to evaluate the association between current e-cigarette use and the prevalence of COPD. As a key secondary aim, we conducted a subgroup analysis focusing on exclusive e-cigarette users-individuals who currently use e-cigarettes but have never smoked traditional cigarettes-to preliminarily explore the independent association. Methods: A comprehensive literature search was conducted in PubMed, Embase, Web of Science, the Cochrane Library, China National Knowledge Infrastructure, and Wanfang Database for studies published up to 12 November 2025. Eligible observational studies that assessed the association between e-cigarette use and the prevalence of COPD were included, and pooled estimates were calculated using a random-effects model. Results: A total of 15 studies were included in the meta-analysis. Current e-cigarette use was associated with a significantly higher odds of having COPD (pooled odds ratio [OR] = 2.03, 95% confidence interval [CI]: 1.61-2.56). Former e-cigarette users also had an elevated association with COPD (OR = 1.82, 95% CI: 1.38-2.41). Subgroup analyses indicated the prevalence of COPD was higher among exclusive e-cigarette users (OR = 2.09, 95% CI: 1.46-3.00), dual users of e-cigarettes and traditional cigarettes (OR = 3.13, 95% CI: 2.01-4.87), and current e-cigarette users with a smoking history (OR = 2.17, 95% CI: 1.41-3.35). Sensitivity analysis supported the robustness of these findings, and no evidence of publication bias was observed. Conclusion: This meta-analysis suggests that current e-cigarette use is associated with a higher prevalence of COPD. This association remained evident among exclusive e-cigarette users, indicating a potential link independent of traditional smoking history. Systematic review registration: https://www.crd.york.ac.uk/PROSPERO/view/CRD420251218716, identifier (CRD420251218716).