Electronic cigarettes and health outcomes: umbrella and systematic review of the global evidence.

Introduction:
This text provides a comprehensive summary of a systematic review conducted to examine the relationship between e-cigarette use and health outcomes. The review integrates an umbrella review of evidence from major independent reviews with a top-up systematic review, following PRISMA guidelines. The review aimed to provide an up-to-date overview of the evidence regarding the health effects of nicotine and non-nicotine e-cigarettes.

Key Points:

* The review identified four hundred eligible publications, including 112 from the NASEM review, 189 from the top-up review search, and 99 further publications cited by other reviews.
* The review found conclusive evidence linking e-cigarette use with poisoning, immediate inhalation toxicity, and e-cigarette or vaping product use-associated lung injury (EVALI).
* Substantial evidence was found that nicotine e-cigarettes can cause dependence or addiction in non-smokers.
* Young non-smokers who use e-cigarettes are more likely than non-users to initiate smoking and become regular smokers.
* There is limited evidence that freebase nicotine e-cigarettes used with clinical support are efficacious aids for smoking cessation.
* Evidence regarding effects on other clinical outcomes, including cardiovascular disease, cancer, development, and mental and reproductive health, is insufficient or unavailable.
* The review rated the certainty of the integrated body of evidence for each health outcome derived from the umbrella and top-up reviews using the GRADE approach.
* The review prioritized study designs most useful for assessing causal effects with respect to the health outcome, in the order: randomized controlled trials, prospective cohort studies, case-control studies, and non-randomized intervention studies.

Main Message:
The main message of this text is that e-cigarettes can be harmful to health, particularly for non-smokers and children, adolescents, and young adults. While e-cigarettes may be beneficial for smokers who use them to completely and promptly quit smoking, their effects on many important health outcomes are uncertain. Better quality evidence is needed regarding the health impact of e-cigarette use, their safety and efficacy for smoking cessation, and effective regulation.

Banks E, Yazidjoglou A, Brown S, et al. Electronic cigarettes and health outcomes: umbrella and systematic review of the global evidence. The Medical journal of Australia. 2023;218(6):267-275. doi:10.5694/mja2.51890