The impact of electronic cigarette use on chronic obstructive pulmonary disease: A systematic review and meta-analysis

Objectives: Electronic cigarette (or e-cigarette) use is increasing globally. To date, there are limited pooled estimates regarding the impact of e-cigarette use on chronic obstructive pulmonary disease (COPD). The present meta-analysis of large-scale population-based observational studies evaluates the impact of e-cigarette use on COPD. Methods: A systematic search of observational studies published between 1/2020-1/2024 was conducted in MEDLINE and Scopus based on PRISMA Guidelines. Results: Of 3670 originally retrieved papers, 7 observational studies (including 4 cross-sectional studies and 3 prospective cohort studies) fulfilled all search criteria and were used for the present meta-analysis which encompassed in total, 3,552,424 participants, including 138,698 cases with COPD. The findings from the random-effects meta-analysis (I² = 22 %, Cochran Q (6) = 7.19, p = 0.307) suggested that use of e-cigarette among non-cigarette users was associated with (pooled Relative Risk, pRR) 1.50-times higher likelihood of COPD (95 % Confidence Interval (CI): 1.27, 1.73). Sensitivity analysis by leave-one-out analysis confirmed the aforementioned results (range of pRR values: 1.46 to 1.61, all p < 0.001). Stratified pooled effect estimates of cross-sectional studies only (pOR = 1.55, 95 % CI: 1.26, 1.84) and of prospective cohort studies only (pRR = 1.52, 95 % CI: 0.98–2.06), revealed that the e-cigarette users exhibit between 52 % and 55 % significantly higher likelihood of COPD. Conclusions: The current meta-analysis highlights that e-cigarette users face an increased risk of developing COPD. Therefore, public health interventions aimed at diminishing e-cigarette are necessary for preventing COPD.