Adverse effects of E-cigarettes or Vapes in otherwise Healthy Young and Middle-aged Adults who have No History of Smoking: A Systematic Review

Abstract : Introduction: The use of Electronic cigarettes and Vapes have been widely accepted as a less-harmful means of smoking when compared to cigarettes. While this is true, the adverse effects and harms of E-cigarettes and Vaping are not inconsequential. Methods: We searched the PubMed database exclusively for Randomized controlled trials, while limiting our search between 2007 – 2023. We initially identified 234 articles from PubMed which were then screened by abstract. Articles were screened for relevance based on the topic of E-cigarettes or Vaping and of adverse effects. Exclusion of 205 studies left 29 full-text articles to assess. Assessing based on our inclusion and exclusion criteria left 6 studies eligible for systematic analysis. Data extraction was performed on each study with focus on baseline demographics and covariates. Using the Jadad-scale, three independent reviewers assessed the methodological quality of each study on a 5 point scale. It was found that 1 study was of poor quality, 4 studies were of moderate quality and 1 study was of good quality. Results: 6 RCTs were included in the analysis with 4 being performed in the United States, 1 in Italy and 1 in Canada. A total of 137 participants were included in the randomized controlled trials published between 2015 and 2021. Acute vaping indicated a positive correlation and dose-response relationship with an increase in CD14, CD16, T-cells, natural killers and monocytes. Furthermore, the findings from the review suggests that EC usage alters expression of the transcriptome in both small airway epithelium (SAE) and alveolar macrophages (AM). However, acute electronic cigarette use does not affect lung and heart functions as long as they do not contain nicotine. Discussion: This systematic review was conducted using Randomized controlled trials, which minimizes bias and adjusts for confounding, with a robust internal validity. Randomization also provides the best means for determining a causal relationship between an intervention and outcome. However the average quality of the included studies are not of good quality and sample size (137 subjects) may be considered quite small and not representative. Database for studies included was limited to only Pubmed. Moreover health-care practitioners must also actively inquire about the recreational use of vapes in youth and adults, as they are becoming popularized due to the misconception of having few harmful effects. Conclusion: Acute use of electronic cigarettes show a significant increase in inflammatory cell and cytokine release, leading to oxidative stress, potential airway remodeling and DNA damage. It was found that acute E-cigarette usage also decreases FEV1, however these changes were not clinically significant towards pulmonary function and cardiac function tests. While this study only assesses the acute effects of electronic cigarette vape usage, further studies must be conducted on the chronic usage of E-cigarettes and their clinical effects.