Johnston 2013

Methods	Study design: Cluster‐randomised controlled trial Unit of randomisation: Schools N schools: 7 (4 intervention schools, 3 control schools) Duration of intervention: 2 years Follow‐up: Immediately after intervention Unit of analysis: Child Setting: Texas, USA Exclusion criteria: Not reported Classification of weight status: Data tables provided by the CDC Start date: Fall 2008 End date: Fall 2010
Participants	N (randomly assigned): 321 (N intervention 186, N control 135) N (followed): 253 (N intervention 153, N control 100) Age: 7 ‐ 9 years, mean age: 7.8 ± 0.4 (intervention group), 7.7 ± 0.4 (control group) Sex: Intervention group 38.2% female, control group 45.9% female Ethnicity: intervention group Hispanic 27.4%, black 26.9%, Asian 24.3%, white 21.5% Control group Hispanic 29.6%, black 26.7%, Asian 16.3%, white 27.4% Reasons for attrition: Absent at follow‐up (N intervention 14, N control 11), no longer at school (N intervention 19, N control 24) Attrition: 21% (68/321)
Interventions	Comparison: Lifestyle education versus standard practice Intervention: Whole‐school lifestyle education programme facilitated by a health professional involving curriculum material taught by trained teachers, school meal modification and nutrition counselling. Compliance with the intervention was assessed through direct weekly observation of teachers by the health professional and verbal self‐report from teachers 1. Nutrition/Diet: Modification of school meals towards nutrient‐dense food. Nutrition counselling was provided on an informal basis by a school nurse 2. Health lifestyle education: Teachers were provided with 50 integrated lessons‐worth of curriculum material aiming to improve healthy diet (increased fruit and vegetable, breakfast, healthy snack, water consumption) and increase physical activity. Teachers were encouraged to teach lifestyle integrated lessons once a week, to conduct health‐related activities every 2 weeks and to hold a school‐wide health event once a semester. The intervention component included provision of additional health information at school functions by health professionals and involvement of school libraries, computers, art, music and physical education in delivery/complementation of lifestyle education. Standard practice: "Even though intervention material was provided to control schools, teachers reported using the material once a month or less often."
Outcomes	Outcome 1: School achievement: End‐of‐year final grades for reading, mathematics and science summarised as the GPA obtained from school records. The grade scale comprises scores between 0 and 100 points for each participant Outcome 2: Obesity indices: Age‐ and gender‐specific BMI percentiles and BMI z‐scores obtained from measured weight and height and by using formulas and data tables provided by the CDC. Overweight was defined as a BMI ≥ 85th percentile
Notes	Authors were contacted No sample size calculation was reported. This study might therefore be at risk of a type two error Funding source: Not disclosed
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "7 schools were randomized using a random number generator"
Allocation concealment (selection bias)	Unclear risk	Judgement comment: No information provided
Blinding of participants and personnel (performance bias) All outcomes	High risk	Judgement comment: Blinding is not possible in lifestyle interventions. Unclear whether participants and personnel were blinded to the purpose of the study (in relation to the outcome of school achievement)
Blinding of outcome assessment (detection bias) All outcomes	High risk	Quote: "Student year‐end final grades for reading, math, and science were obtained from the school." Judgement comment: Teachers in the school were aware of the group allocation
Incomplete outcome data (attrition bias) All outcomes	Low risk	Quote: "Models were developed for both completers and intention‐to‐treat using the last observation carried forward (LOCF) method"
Selective reporting (reporting bias)	Unclear risk	Judgement comment: No information provided
Comparability of baseline groups	Low risk	Quote: "No differences were found between conditions with respect to baseline demographic or anthropometric variables" Judgement comment: Baseline GPA of intervention and control groups indicated no statistically significant differences between experimental groups
Cross‐contamination	Unclear risk	Quote: "All elementary schools (N=41 schools) from a large suburban independent school district located southwest of Houston, TX were recruited to participate in the study." Judgement comment: The geographic proximity of the schools is unclear
Other bias	Low risk	Judgement comment: None detected