E-cigarettes and smoking cessation: evidence from a systematic review and meta-analysis.

BACKGROUND: E-cigarettes are currently being debated regarding their possible role in smoking cessation and as they are becoming increasingly popular, the research to date requires investigation. OBJECTIVES: To investigate whether the use of e-cigarettes is associated with smoking cessation or reduction, and whether there is any difference in efficacy of e-cigarettes with and without nicotine on smoking cessation. DATA SOURCES: A systematic review of articles with no limit on publication date was conducted by searching PubMed, Web of Knowledge and Scopus databases. METHODS: Published studies, those reported smoking abstinence or reduction in cigarette consumption after the use of e-cigarettes, were included. Studies were systematically reviewed, and meta-analyses were conducted using Mantel-Haenszel fixed-effect and random-effects models. Degree of heterogeneity among studies and quality of the selected studies were evaluated. RESULTS: Six studies were included involving 7,551 participants. Meta-analyses included 1,242 participants who had complete data on smoking cessation. Nicotine filled e-cigarettes were more effective for cessation than those without nicotine (pooled Risk Ratio 2.29, 95%CI 1.05-4.97). Amongst 1,242 smokers, 224 (18%) reported smoking cessation after using nicotine-enriched e-cigarettes for a minimum period of six months. Use of such e-cigarettes was positively associated with smoking cessation with a pooled Effect Size of 0.20 (95%CI 0.11-0.28). Use of e-cigarettes was also associated with a reduction in the number of cigarettes used. LIMITATIONS: Included studies were heterogeneous, due to different study designs and gender variation. Whilst we were able to comment on the efficacy of nicotine vs. non-nicotine e-cigarettes for smoking cessation, we were unable to comment on the efficacy of e-cigarettes vs. other interventions for cessation, given the lack of comparator groups in the studies included in this meta-analysis. CONCLUSIONS: Use of e-cigarettes is associated with smoking cessation and reduction. More randomised controlled trials are needed to assess effectiveness against other cessation methods.

Electronic cigarettes: patterns of use, health effects, use in smoking cessation and regulatory issues.

BACKGROUND: Electronic cigarettes (e-cigarettes) are battery-powered devices that vaporize a liquid solution to deliver a dose of inhaled nicotine to the user. There is ongoing debate regarding their regulation. OBJECTIVES: This comprehensive narrative review aimed to discuss key issues including usage patterns, health effects, efficacy in smoking cessation and regulatory concerns with a view to informing future regulation and research agendas. METHODS: PubMed, Scopus and Web of Science databases were searched using the terms (electronic cigarettes OR e-cigarettes) for articles in English, relevant to humans and published during January 2009-January 2014. RESULTS: The literature search revealed 37 relevant articles. Findings suggest that e-cigarettes are mostly used by middle-aged current smokers, particularly males, to help them for quitting or for recreation. E-cigarettes contain very low levels of multiple toxic substances such as formaldehyde and acrolein, but these levels are many times lower than those found in cigarettes. They were found to have effectiveness in aiding smoking cessation to a limited degree. Debate continues regarding regulating their use for cessation versus heavy restrictions to control recreational use on the basis that it perpetuates nicotine addiction. CONCLUSIONS: The cytotoxicity and long term health effects of e-cigarettes are unknown. Nevertheless the e-cigarette market continues to expand, largely driven by middle-aged smokers who claim to be using e-cigarettes in an attempt to reduce or quit smoking. E-cigarettes may have some potential as smoking cessation aids and, in the researchers' view, should therefore be subject to further research and regulation similar to other nicotine replacement therapies.