Williamson 2012.

Study characteristics
Methods	Study name: LA health study Study design: cluster‐RCT Intervention period: 28 months Follow‐up period (post‐intervention): nil Differences in baseline characteristics: reported Reliable outcomes: reported Protection against contamination: NR Unit of allocation: school clusters Unit of analysis: individual accounting for clustering
Participants	N (controls baseline) = 587 N (controls follow‐up) = 18 months: 421, 28 months: 447 N (primary prevention (PP) baseline) = 713 N (PP follow‐up) = 18 months: 584, 28 months: 489 N (combination PP + secondary prevention (SP) baseline) = 760 N (combination PP + SP follow‐up) = 18 months: 614, 28 months: 553 Setting (and number by study group): 17 school clusters (each cluster described as an exclusive set of elementary schools and the middle or junior high school into which they feed): primary prevention (5 clusters), combination of primary prevention and secondary prevention (6 clusters) and control (6 clusters) Recruitment: top‐down approach, i.e. first sought the support of the highest levels of school administration and progressively sought support at lower levels. Students were recruited in the school environment by a variety of methods, including presentations to students and parents, fliers, and word of mouth. Geographic region: Louisiana, USA Percentage of eligible population enrolled: 74% school clusters; 42% participants Mean age: PP: 10.5 ± 1.2; SP: 10.5 ± 1.2; control: 10.6 ± 1.2 Sex: PP: 58.8% female; SP: 57.2%; control: 60% female
Interventions	Aim: to test the efficacy of PP programme and a combination of PP and a SP programme in comparison to a control group for prevention of weight/fat gain in the entire sample and overweight children Name: LA health study Intervention: PP Modification of the school environment to promote healthy nutrition and PA with 3 primary objectives: modify environmental cues related to healthy eating and activity modify the cafeteria food service programme modify the PE programmes as described in the SPARK study (reference 24) and to reduce sedentary behaviour. The programme used an environmental approach that was developed and tested in the 'Wise mind' study. Recommendations from the American Academy of Pediatrics were followed. The contents of vending machines were modified to meet dietary guideline criteria and activity goals set 60 min of moderate to vigorous activity per day and < 2 h/day of TV viewing and video gaming Intervention: PP + SP Combination of PP (identical to above) and SP. SP employed a classroom instruction component combined with an internet‐based approach. The internet intervention of this study was delivered as part of regular classroom instruction, combined with synchronous (online) internet counselling and asynchronous (email) communications for children and their parents. Tailoring: the website was programmed to recognise whether a participant was overweight or obese at baseline and slightly different programs were presented to overweight and non‐overweight children, which was effective for minimising the potential for stigmatising overweight children. Control The control group for the RCT received none of the prevention components that are hypothesised to yield weight gain prevention. Teachers received information about the LA health project, instruction on modelling and implementing content standards as they relate to LA health, and technology training critical to project implementation. Treatment‐specific training began after random assignment of schools, and was held at locations convenient for the teachers Diet and PA with and without added classroom and internet education component vs control
Outcomes	Outcome measures Primary outcome: zBMI, % body fat Secondary outcomes: PA, energy intake Process evaluation: reported (integrity)
Implementation‐related factors	Theoretical basis: Social Learning theory Resources for intervention implementation: reported Who delivered the intervention: reported PROGRESS categories assessed at baseline: gender, race/ethnicity, SES (enrolment in the free or reduced‐cost lunch programme) PROGRESS categories analysed at outcome: gender, race/ethnicity Outcomes relating to harms/unintended effects: NR Intervention included strategies to address diversity or disadvantage: NR however 81.7% of participants described as being low SES at baseline Economic evaluation: NR
Notes	NCT00289315 Funding: this project was supported by the National Institute for Child Health and Human Development of the NIH (R01 HD048483) and the U.S. Department of Agriculture (58‐6435‐4‐90). In addition, this work was partially supported by the NORC Center Grant #1P30 DK072476 entitled “Nutritional Programming: Environmental and Molecular Interactions” sponsored by NIDDK, and C. Martin was supported by NIH grant K23 DK068052 (PI: C. Martin)
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	17 school clusters were randomly assigned to 1/3 study arms
Allocation concealment (selection bias)	Unclear risk	NR
Blinding (performance bias and detection bias) All outcomes	Low risk	Quote: "measurements were conducted by two independent assessment teams who travelled together"
Incomplete outcome data (attrition bias) All outcomes	Low risk	Attrition rate was 14%, 16% and 24% in PP, SP and control respectively at end of study Quote: "The results were compared with results from a last observation carried forward (LOCF) intent‐to‐treat approach to evaluate the reliability of the findings and the same results were found"
Selective reporting (reporting bias)	Unclear risk	Protocol/trial registration document seen. All outcomes reported. However both intervention arms were combined and compared with control as no significant difference between groups at follow‐up for primary outcomes
Other bias	Low risk	None identified
Other bias‐ timing of recruitment of clusters	Low risk	Figure and text both indicate recruitment happened prior to randomisation