Foster 2008.

Study characteristics
Methods	Study design: cluster‐RCT Intervention period: 2 years Follow‐up period (post‐intervention): nil Differences in baseline characteristics: reported Reliable outcomes: reported (anthropometry, dietary intake, PA and sedentary behaviour) Protection against contamination: all schools were under the direction of the district's Food Service Division, which agreed to make the necessary changes in intervention schools, while making no changes to the control schools. Unit of allocation: school Unit of analysis: individual Study authors imputed missing data using the multiple imputation procedure with the Markov chain Monte Carlo algorithm as well as the LOCF method for comparison
Participants	N (controls baseline) = 600 N (controls follow‐up) = 365 N (interventions baseline) = 749 N (interventions follow‐up) = 479 Setting (and number by study group): schools (N = 5 intervention, N = 5 control) Recruitment: within schools, written parental consent and child assent required Geographic region: Philadelphia, USA Percentage of eligible population enrolled: school level: 83%. Across participating schools, consent rate was 70% ± 15% Mean age: intervention, 11.13 ± 1 years; control, 11.2 ± 1 years Sex: intervention, 52% female; control: 55% female
Interventions	SNPI‐School Nutrition Policy Initiative ‐ 5 components School self assessment Assessed environments using the CDC School Health Index School formed a Nutrition Advisory Group to guide assessment Schools subsequently developed an action plan for change with a variety of strategies, e.g. limiting use of food as reward/punishment, fundraising etc Nutrition education 50 h of food and nutrition education/student/school year based on National Center for Education Statistics guidelines Integrated into classroom subjects; integrative and interdisciplinary Nutrition policy All food sold and served in the schools was changed to meet the nutritional standards based on dietary guidelines for Americans Social marketing Several techniques: raffle tickets; slogan and character development Family/parent outreach Home and school association meetings, report card nights, parent education meetings, weekly nutrition workshops. Parent challenges re PA and healthy eating. Schools encouraged parents to send healthy foods and discouraged unhealthy foods Staff training All school staff offered ~10 hours/year of training in nutrition education to receive curricula and supporting materials e.g. Planet Health and Know your body, and curriculum lesson packets etc Combined effects of dietary interventions and PA interventions vs control
Outcomes	Incidence of overweight and obesity Prevalence and remission of overweight and obesity Dietary intake and PA Sedentary behaviours Potential adverse effects Process evaluation: NR
Implementation‐related factors	Theoretical basis: settings‐based approach; CDC Guidelines to Promote Lifelong Healthy Eating and PA Resources for intervention implementation (e.g. funding needed or staff hours required): NR Who delivered the intervention: reported PROGRESS categories assessed at baseline: reported (race, gender, SES) PROGRESS categories analysed at outcome: reported (race, gender) Outcomes relating to harms/unintended effects: reported Intervention included strategies to address diversity or disadvantage: NR Economic evaluation: NR
Notes	Funding: this study was supported by grants from the CDC (R06/CCR321534‐01) and the US Department of Agriculture/Food and Nutrition Service through the Pennsylvania Nutrition Education Program as part of Food Stamp Nutrition Education
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	NR Quote: "the schools were randomly assigned as intervention or control schools."
Allocation concealment (selection bias)	Unclear risk	NR Quote: "Schools within each cluster were approached to participate in a predetermined, random order. When 2 schools in each cluster agreed to participate, the schools were randomly assigned as intervention or control schools."
Blinding (performance bias and detection bias) All outcomes	Unclear risk	Heights and weights were measured annually on a digital scale and wall‐mounted stadiometer by a trained research team with a standardised protocol. The team was not blinded to treatment condition.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Clusters not lost and individual dropout NR but they did imputations and sensitivity analysis. Quote: "To account for attrition at the student level, we imputed missing data at year 2 using the multiple imputation (MI) procedure with the Markov chain Monte Carlo algorithm.....In addition, to assess the consistency of our findings, data were analysed using the more conventional baseline carried forward and last observation carried forward methods."
Selective reporting (reporting bias)	Unclear risk	Protocol/trial registration document were unavailable
Other bias	Low risk	No additional threats to validity.
Other bias‐ timing of recruitment of clusters	Low risk	Recruitment happened before randomisation. Quote: "Schools within each cluster were approached to participate in a predetermined, random order. When 2 schools in each cluster agreed to participate, the schools were randomly assigned as intervention or control schools."