title: Electronic cigarette, effective or harmful for quitting smoking and respiratory health: A quantitative review papers.
abstract: BACKGROUND
  In recent years, electronic cigarettes (ECs) have been heavily advertised as an alternative smoking device as well as a possible cessation method. We aimed to review all published scientific literature pertaining to ECs and to present a simple conclusion about their effects for quitting smoking and respiratory health.
  
  
  METHODS
  This was a cross-sectional study with a search of PubMed, limited to English publications upto September 2014. The total number of papers which had ECs in its title and their conclusions positive or negative regarding ECs effects were computed. The number of negative papers was subtracted from the number of positive ones to make a score.
  
  
  RESULTS
  Of the 149 articles, 137 (91.9%) were accessible, of which 68 did not have inclusion criteria. In the 69 remaining articles, 24 studies supported ECs and 45 considered these to be harmful. Finally, based on this evidence, the score of ECs (computed result with positive minus negative) was -21.
  
  
  CONCLUSIONS
  Evidence to suggest that ECs may be effective and advisable for quitting smoking or a safe alternative for smoking is lacking and may instead harm the respiratory system. However, further studies are needed.
authors.affiliation: Tobacco Prevention and Control Research Center, National Research Institute of Tuberculosis and Lung Diseases, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Gholamreza
authors.initials: G
authors.lastname: Heydari
authors.affiliation: Department of Community Oral Health, School of Dentistry, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Arezoo Ebn
authors.initials: AE
authors.lastname: Ahmady
authors.affiliation: Department of Library, National Research Institute of Tuberculosis and Lung Diseases, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Fahimeh
authors.initials: F
authors.lastname: Chamyani
authors.affiliation: Chronic Respiratory Research Center, National Research Institute of Tuberculosis and Lung Diseases, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Mohammadreza
authors.initials: M
authors.lastname: Masjedi
authors.affiliation: Telemedicine Research Center, National Research Institute of Tuberculosis and Lung Diseases, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Lida
authors.initials: L
authors.lastname: Fadaizadeh
keywords: Cessation; e-cigarettes; respiration; smoking; tobacco; vaping