title: E-cigarettes and smoking cessation: evidence from a systematic review and meta-analysis.
abstract: 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.
  
  
  OBJECTIVE
  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.
  
  
  METHODS
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: The Mary MacKillop Institute for Health Research, Australian Catholic University, Melbourne, Australia; St Vincent's Centre for Nursing Research (SVCNR), Australian Catholic University, Melbourne, Australia; The Cardiovascular Research Centre (CvRC), Australian Catholic University, Melbourne, Australia.
authors.forename: Muhammad Aziz
authors.initials: MA
authors.lastname: Rahman
authors.affiliation: The Cardiovascular Research Centre (CvRC), Australian Catholic University, Melbourne, Australia; The University of Melbourne, Melbourne, Australia.
authors.forename: Nicholas
authors.initials: N
authors.lastname: Hann
authors.affiliation: The Cardiovascular Research Centre (CvRC), Australian Catholic University, Melbourne, Australia; The University of Melbourne, Melbourne, Australia; St Vincent's Hospital, Melbourne, Australia.
authors.forename: Andrew
authors.initials: A
authors.lastname: Wilson
authors.affiliation: School of Allied Health, Faculty of Health Sciences, Australian Catholic University, Melbourne, Australia.
authors.forename: George
authors.initials: G
authors.lastname: Mnatzaganian
authors.affiliation: St Vincent's Centre for Nursing Research (SVCNR), Australian Catholic University, Melbourne, Australia; The Cardiovascular Research Centre (CvRC), Australian Catholic University, Melbourne, Australia; St Vincent's Hospital, Melbourne, Australia.
authors.forename: Linda
authors.initials: L
authors.lastname: Worrall-Carter
mesh_terms: D066300:Electronic Nicotine Delivery Systems; D006801:Humans; D009538:Nicotine / Q000032:analysis; D017063:Outcome Assessment, Health Care; D016540:Smoking Cessation / Q000379:methods*
chemical_list: D009538:Nicotine
references.citation: Eur J Health Law. 2014 Apr;21(2):161-75
references.pmid: 24851651
references.citation: Tob Control. 2014 Mar;23(2):133-9
references.pmid: 23467656
references.citation: BMC Public Health. 2006;6:300
references.pmid: 17156479
references.citation: Eur Respir J. 2011 Nov;38(5):1005-11
references.pmid: 21565921
references.citation: BMJ. 2013;346:f3840
references.pmid: 23771038
references.citation: Addiction. 2014 Sep;109(9):1531-40
references.pmid: 24846453
references.citation: Chest. 2013 Nov;144(5):1609-14
references.pmid: 23868661
references.citation: J Epidemiol Community Health. 1998 Jun;52(6):377-84
references.pmid: 9764259
references.citation: Cochrane Database Syst Rev. 2013;5:CD009329
references.pmid: 23728690
references.citation: Am J Prev Med. 2011 Apr;40(4):472-5
references.pmid: 21406283
references.citation: Yale J Health Policy Law Ethics. 2013 Summer;13(2):326-74
references.pmid: 24340824
references.citation: Control Clin Trials. 1986 Sep;7(3):177-88
references.pmid: 3802833
references.citation: Ther Adv Drug Saf. 2014 Apr;5(2):67-86
references.pmid: 25083263
references.citation: Lancet. 2013 Nov 16;382(9905):1629-37
references.pmid: 24029165
references.citation: Addiction. 2011 Nov;106(11):2017-28
references.pmid: 21592253
references.citation: Intern Emerg Med. 2014 Aug;9(5):537-46
references.pmid: 23873169
references.citation: BMJ. 2003 Sep 6;327(7414):557-60
references.pmid: 12958120
references.citation: PLoS One. 2013;8(6):e66317
references.pmid: 23826093
references.citation: Drug Alcohol Rev. 2013 Mar;32(2):133-40
references.pmid: 22994631
references.citation: Cochrane Database Syst Rev. 2012;10:CD008286
references.pmid: 23076944
references.citation: BMC Public Health. 2011;11:786
references.pmid: 21989407
references.citation: Cochrane Database Syst Rev. 2008;(1):CD006886
references.pmid: 18254119
references.citation: Addict Sci Clin Pract. 2013;8:5
references.pmid: 23497603
references.citation: Int J Environ Res Public Health. 2013 Feb;10(2):446-61
references.pmid: 23358230
references.citation: Harm Reduct J. 2013;10:19
references.pmid: 24090432
references.citation: Clin Rev Allergy Immunol. 2014 Feb;46(1):34-53
references.pmid: 23673789
references.citation: Tob Induc Dis. 2014 Dec 15;12(1):21
references.pmid: 25745382
references.citation: Ther Adv Chronic Dis. 2014 Mar;5(2):50-61
references.pmid: 24587890
references.citation: Addiction. 2005 Aug;100(8):1074-89
references.pmid: 16042638
references.citation: Am J Public Health. 2010 Feb;100(2):341-8
references.pmid: 20019322
references.citation: Nicotine Tob Res. 2009 Nov;11(11):1274-9
references.pmid: 19793786
references.citation: Eur Heart J. 2000 Mar;21(6):438-45
references.pmid: 10681484
references.citation: Monaldi Arch Chest Dis. 2013 Mar;79(1):12-9
references.pmid: 23741941
references.citation: Am J Public Health. 2013 Sep;103(9):e57-62
references.pmid: 23865700
references.citation: Cochrane Database Syst Rev. 2013;5:CD000165
references.pmid: 23728631
references.citation: Addict Behav. 2014 Feb;39(2):491-4
references.pmid: 24229843
references.citation: Nicotine Tob Res. 2006 Aug;8(4):555-64
references.pmid: 16920653
references.citation: Spine (Phila Pa 1976). 2003 Jun 15;28(12):1290-9
references.pmid: 12811274
references.citation: PLoS Med. 2009 Jul 21;6(7):e1000097
references.pmid: 19621072