title: A systematic review of how researchers characterize the school environment in determining its effect on student obesity.
abstract: BACKGROUND
  Obesity in early childhood is a robust predictor of obesity later in life. Schools provide unparalleled access to children and have subsequently become major intervention sites. However, empirical evidence supporting the effectiveness of school-based interventions against childhood obesity is of limited scope and unknown quality. The aim of this systematic review is to critically assess how researchers have characterized the school environment in determining its effect on childhood weight status in order to improve the quality and consistency of research in this area. We conducted a narrative review with a systematic search of the literature in line with PRISMA guidelines (2009). Original peer-reviewed research articles in English were searched from Medline, EMBASE, CENTRAL, CINAHL and PsycINFO databases from earliest record to January 2014. We included empirical research that reported at least one measure of the primary/elementary school environment and its relationship with at least one objective adiposity-related variable for students aged 4-12 years. Two authors independently extracted data on study design, school-level factors, student weight status, type of analysis and effect.
  
  
  RESULTS
  Five studies met the inclusion criteria. Each study targeted different parts of the school environment and findings across the studies were not comparable. The instruments used to collect school-level data report no validity or reliability testing.
  
  
  CONCLUSIONS
  Our review shows that researchers have used instruments of unknown quality to test if the school environment is a determinant of childhood obesity, which raises broader questions about the impact that schools can play in obesity prevention.
authors.affiliation: Nuffield Department of Population Health, University of Oxford, Old Road Campus, Roosevelt Drive, Oxford, OX3 7LF United Kingdom ; World Health Organization Collaborating Centre for Population Approaches to Non-Communicable Disease Prevention, University of Oxford, Oxford, UK.
authors.forename: Kyle
authors.initials: K
authors.lastname: Turner
authors.affiliation: Nuffield Department of Population Health, University of Oxford, Old Road Campus, Roosevelt Drive, Oxford, OX3 7LF United Kingdom ; World Health Organization Collaborating Centre for Population Approaches to Non-Communicable Disease Prevention, University of Oxford, Oxford, UK.
authors.forename: Charlie
authors.initials: C
authors.lastname: Foster
authors.affiliation: World Health Organization Collaborating Centre for Obesity Prevention, Deakin University, Burwood, 3125, Victoria Australia.
authors.forename: Steven
authors.initials: S
authors.lastname: Allender
authors.affiliation: Nuffield Department of Population Health, University of Oxford, Old Road Campus, Roosevelt Drive, Oxford, OX3 7LF United Kingdom.
authors.forename: Emma
authors.initials: E
authors.lastname: Plugge
keywords: Childhood obesity; Environmental measurement; School