title: Electronic nicotine delivery systems and/or electronic non-nicotine delivery systems for tobacco smoking cessation or reduction: a systematic review and meta-analysis.
abstract: A systematic review and meta-analysis to investigate the impact of electronic nicotine delivery systems (ENDS) and/or electronic non-nicotine delivery systems (ENNDS) versus no smoking cessation aid, or alternative smoking cessation aids, in cigarette smokers on long-term tobacco use.
  
  
  
  Searches of MEDLINE, EMBASE, PsycInfo, CINAHL, CENTRAL and Web of Science up to December 2015.
  
  
  
  Randomised controlled trials (RCTs) and prospective cohort studies.
  
  
  
  Three pairs of reviewers independently screened potentially eligible articles, extracted data from included studies on populations, interventions and outcomes and assessed their risk of bias. We used the Grading of Recommendations Assessment, Development and Evaluation approach to rate overall certainty of the evidence by outcome.
  
  
  
  Three randomised trials including 1007 participants and nine cohorts including 13 115 participants proved eligible. Results provided by only two RCTs suggest a possible increase in tobacco smoking cessation with ENDS in comparison with ENNDS (RR 2.03, 95% CI 0.94 to 4.38; p=0.07; I2=0%, risk difference (RD) 64/1000 over 6 to 12 months, low-certainty evidence). Results from cohort studies suggested a possible reduction in quit rates with use of ENDS compared with no use of ENDS (OR 0.74, 95% CI 0.55 to 1.00; p=0.051; I2=56%, very low certainty).
  
  
  
  There is very limited evidence regarding the impact of ENDS or ENNDS on tobacco smoking cessation, reduction or adverse effects: data from RCTs are of low certainty and observational studies of very low certainty. The limitations of the cohort studies led us to a rating of very low-certainty evidence from which no credible inferences can be drawn. Lack of usefulness with regard to address the question of e-cigarettes' efficacy on smoking reduction and cessation was largely due to poor reporting. This review underlines the need to conduct well-designed trials measuring biochemically validated outcomes and adverse effects.
authors.affiliation: Department of Anaesthesiology, Botucatu Medical School, UNESP-Univ Estadual Paulista, São Paulo, Brazil.|McMaster Institute of Urology, McMaster University, Hamilton, Ontario, Canada.|Institute of Science and Technology, Department of Biosciences and Oral Diagnosis, Unesp-Univ Estadual Paulista, São José dos Campos, Brazil.
authors.forename: Regina
authors.initials: R
authors.lastname: El Dib
authors.affiliation: Research Institute-Hospital do Coração (HCor), São Paulo, Brazil.
authors.forename: Erica A
authors.initials: EA
authors.lastname: Suzumura
authors.affiliation: Department of Internal Medicine, Clinical Research Institute (CRI), Center for Systematic Reviews in Health Policy and Systems Research (SPARK), American University of Beirut, Beirut, Lebanon.|Department of Clinical Epidemiology & Biostatistics, McMaster University, Hamilton, Ontario, Canada.
authors.forename: Elie A
authors.initials: EA
authors.lastname: Akl
authors.affiliation: Department of Pharmacy, Tanta Chest Hospital, Tanta, Egypt.
authors.forename: Huda
authors.initials: H
authors.lastname: Gomaa
authors.affiliation: Department of Clinical Epidemiology & Biostatistics, McMaster University, Hamilton, Ontario, Canada.|Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Arnav
authors.identifier: 0000-0002-0931-7851
authors.initials: A
authors.lastname: Agarwal
authors.affiliation: Department of Clinical Epidemiology & Biostatistics, McMaster University, Hamilton, Ontario, Canada.
authors.forename: Yaping
authors.initials: Y
authors.lastname: Chang
authors.affiliation: Department of Community Medicine, Postgraduate Institute of Medical Sciences, Rohtak, Haryana, India.
authors.forename: Manya
authors.initials: M
authors.lastname: Prasad
authors.affiliation: Department of Clinical Epidemiology & Biostatistics, McMaster University, Hamilton, Ontario, Canada.|Isfahan Medical Education Research Centre, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Vahid
authors.initials: V
authors.lastname: Ashoorion
authors.affiliation: Department of Clinical Epidemiology & Biostatistics, McMaster University, Hamilton, Ontario, Canada.
authors.forename: Diane
authors.initials: D
authors.lastname: Heels-Ansdell
authors.affiliation: Department of Epidemiology, Robert Stempel College of Public Health and Social Work, Florida International University, Miami, Florida, USA.
authors.forename: Wasim
authors.initials: W
authors.lastname: Maziak
authors.affiliation: Department of Clinical Epidemiology & Biostatistics, McMaster University, Hamilton, Ontario, Canada.|Department of Medicine, McMaster University, Hamilton, Ontario, Canada.
authors.forename: Gordon
authors.initials: G
authors.lastname: Guyatt
mesh_terms: D001521:Behavior Therapy; D066300:Electronic Nicotine Delivery Systems; D006801:Humans; D018722:Nicotinic Agonists / Q000008:administration & dosage; D016032:Randomized Controlled Trials as Topic; D016540:Smoking Cessation / Q000379:methods*; D000073869:Tobacco Smoking / Q000628:therapy*; D061485:Tobacco Use Cessation Devices
chemical_list: D018722:Nicotinic Agonists
keywords: ENDS; GRADE; electronic cigarettes; smoking cessation; systematic review