title: Anti-tobacco policy in schools: upcoming preventive strategy or prevention myth? A review of 31 studies.
abstract: OBJECTIVE
  To summarise the evidence on effectiveness of school anti-tobacco policies (exposure) in preventing tobacco use (outcome) among high school students.
  
  
  METHODS
  The search was conducted between 1 September and 30 November 2011 on six electronic databases with keywords: 'policy', 'ban', 'restriction' and 'environment' in combination with 'adolescent' or 'student', 'school' and 'smoking' in titles, abstracts or keywords. Restrictions were made to articles published in English.
  
  
  METHODS
  Studies were included if they targeted the relevant grades/age; reported at least one outcome measure of students' ever or current tobacco use; reported on the effects of exposure to policy separately from other interventions. Inclusion criteria were assessed independently by two of the coauthors. Of 2723 articles initially identified, 31 articles met the inclusion criteria (1.1%).
  
  
  METHODS
  Independent multiple observers extracted the data following the GRADE system guidelines to classify the level of evidence in relation to the review objective.
  
  
  RESULTS
  Studies were very heterogeneous in the definitions of exposure to school anti-tobacco policy and of tobacco use, adjustment for potential confounders and reporting of results, therefore summary quantitative measures of effect were not calculated. Qualitative summary statements were derived by reviewing the results reported in text and tables for distinct policy constructs. Evidence could be classified as low or very low, resting on cross-sectional studies with high risk of bias. Studies were rather consistent in indicating that comprehensive smoking bans, clear rules, strict policy enforcement, availability of education and prevention were associated with decreased smoking prevalence. Formally adopted and written policies, surveillance of students' behaviour and presence/severity of sanctions were not consistently associated to students' tobacco use.
  
  
  CONCLUSIONS
  The evidence concerning the effectiveness of a school policy alone in preventing youth tobacco use is weak and inconclusive. Experimental studies or observational studies with longitudinal design are warranted, employing clear definitions of policy components and careful control for confounding.
authors.affiliation: Department of Public Health Sciences, Karolinska Institutet, Centre for Epidemiology and Community Medicine, Health Care District, Stockholm, Sweden.
authors.forename: Maria Rosaria
authors.initials: MR
authors.lastname: Galanti
authors.affiliation: Department of Translational Medicine, Avogadro University, Novara, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Coppo
authors.affiliation: Department of Public Health Sciences, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Elin
authors.initials: E
authors.lastname: Jonsson
authors.affiliation: Department of Public Health Sciences, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Sven
authors.initials: S
authors.lastname: Bremberg
authors.affiliation: Department of Translational Medicine, Avogadro University, Novara, Italy.
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Faggiano
mesh_terms: D000293:Adolescent; D002648:Child; D003430:Cross-Sectional Studies; D003479:Curriculum; D005260:Female; D006293:Health Promotion / Q000458:organization & administration*; D006801:Humans; D008297:Male; D011322:Primary Prevention / Q000458:organization & administration; D012572:School Health Services / Q000458:organization & administration*; D012574:Schools / Q000458:organization & administration; D016540:Smoking Cessation / Q000379:methods*; D000074606:Smoking Prevention; D013334:Students / Q000706:statistics & numerical data; D014028:Tobacco Smoke Pollution / Q000517:prevention & control*
chemical_list: D014028:Tobacco Smoke Pollution
keywords: Environment; Prevention; Public policy