Davis 2016.

Study characteristics
Methods	Study design: cluster‐RCT Length of follow‐up from baseline: 7 months Unit of allocation: Head Start centres Unit of analysis: child
Participants	Service type: centre‐based (Head Start) Operation: Head Start centres Country (region): USA (New Mexico) Country income classification: high Low‐SES sample: yes Population description: a primarily Hispanic or American Indian student population and a location in a nonmetropolitan community within 150 miles (240 km) of the research centre. Inclusion criteria: Head Start centres were eligible for the study if they had at least 2 classrooms, ≥ 15 3‐year‐old children enrolled, a retention rate of at least 80% over 2 school years, a primarily Hispanic or American Indian student population and a location in a nonmetropolitan community within 150 miles (240 km) of the research centre. Exclusion criteria: Head Start centres housing other prekindergarten programs were excluded. Number of services randomised: 16 centres (8 intervention, 8 control) Number of children randomised: 1898 (945 intervention, 871 control) Characteristics Children Age: 2 years: 1.6%; 3 years: 41.1%; 4 years: 55.4%; 5 years: 1.8% Gender (% female): 47.4% Ethnicity: Hispanic: 57.2%; non‐Hispanic: 42.8% Parents Age (years): not reported Gender (% female): not reported Ethnicity: centre race/ethnicity: American Indian: 40.6%; Hispanic: 59.4% Parent/family SES: not reported Method of recruitment: Head Start centres were recruited by a community engagement specialist on the research team. Missing data/dropout: all ECEC services were retained. 74% of eligible population consented to participate. 99% of consenting participants provided data. Reasons for dropout: graduation or transfer to prekindergarten classes, the difficulty in instituting environmental and policy changes and the large effect size required by the small number of study sites. Characteristics of dropouts: not reported
Interventions	Programme name: CHILE: Child Health Initiatative for Lifelong Eating and Exercise Number of conditions: 1 intervention, 1 control Intervention duration: 2 years Intervention setting: ECEC, home and local community Intervention strategies: Health curriculum Children Education: a nutrition and physical activity curriculum for the Head Start centres provided to children. Each lesson incorporates child's development Head Start domains such as emotional/social, literacy and mathematics. Ethos and environment Children Exposure: children were provided opportunities to try new fruits and vegetables and to participate in physical activity during daily class activities. Menu modification: as new fruits and vegetables were introduced to children, they were incorporated in the school menu. ECEC staff Training: quarterly professional development for Head Start teachers and food service staff. Hands‐on sessions provide staff with information about physical activity and nutrition and technical assistance for implementing the intervention. Service Policy: policy changes were made for the food service to switch to healthier food products. Partnerships Families Resources: take‐home materials about nutrition and physical activity were provided to families. Events: 2 family events reinforcing these messages during the school year. Community Access: increasing availability and visibility of healthier food options in local grocery stores and providing recipes and nutrition‐related information to families while shopping. Healthcare Engagement: local healthcare providers were asked to emphasise healthy eating and physical activity during routine patient visits and health professionals were invited to attend family events to show support for the intervention. Intensity of intervention: nutrition curriculum to be incorporated into Head Start learning domains including literacy, maths or science; addition of 30 min of physical activity to daily class activities; quarterly professional development (8 sessions) for ECEC staff; in‐class nutrition lessons provide children multiple exposures to each novel fruit or vegetable; take home materials for families 2 times/year Intervention delivered by: research team, ECEC staff, healthcare staff Modality: face‐to‐face, written Theoretical basis: Socioecological approach Description of control: usual care
Outcomes	Outcomes relating to child dietary intake: not reported Outcomes relating to child physical measures: Underweight, healthy weight, overweight, obese, adjusted BMI z‐score Number of participants analysed Intervention baseline: 210 Intervention follow‐up: 157 Control baseline: 226 Control follow‐up: 174 Data collection measure: objectively measured (CDC) Data collector: researcher Validity of measures used: not reported Outcome relating to child language and cognitive performance: not reported Outcome relating to child social/emotional measures: not reported Outcome relating to child quality of life: not reported Outcome relating to cost: not reported Outcome relating to adverse consequences: not reported
Notes	Funding source: The National Institute of Diabetes and Digestive and Kidney Diseases (Grant R01 DK72958)
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Head Start centres were stratified by race/ethnicity and average BMI. A random uniform variable was generated for each centre. Centres with smaller values within each stratum were assigned to the intervention group until desired sample sizes were achieved.
Allocation concealment (selection bias)	Low risk	Before allocation, centres were stratified according to the race/ethnicity and average BMI of the centres' population. Randomisation occurred after all centres were recruited.
Blinding of participants and personnel (performance bias) Physical outcomes	Low risk	We assumed that due to the nature of the intervention, ECEC service staff and study personnel delivering the intervention were not blind to the study allocation. However, the outcome is not likely to be influenced by lack of blinding.
Blinding of outcome assessment (detection bias) Physical outcomes	Low risk	Blinding not reported, however children's height and weight were assessed at the centres and were not likely to be influenced by lack of blinding.
Incomplete outcome data (attrition bias) Physical outcomes	High risk	Data were available for 157 (75%) participants in the intervention group and 174 (77%) participants in the control group. Study authors stated that "Limitations of the CHILE study included the drop out of students due to graduation or transfer to prekindergarten classes." Due to the magnitude of missing data over the short‐term and long‐term follow‐up, the risk of bias was assessed as high.
Selective reporting (reporting bias)	Unclear risk	Outcomes are not clearly reported in the trial registration or trial protocol, so it was unclear whether there was selective outcome reporting.
Recruitment bias	Low risk	Individual recruitment occurred prior to cluster randomisation.
Baseline imbalance	Low risk	The intervention and comparison groups did not differ significantly at baseline.
Loss of clusters	Low risk	No loss of clusters
Incorrect analysis	Low risk	Study authors stated that "Analyses accounted for repeated measurements for Head Start centers and children by including random effects for each center and child."
Contamination	Unclear risk	No evidence to make assessment
Other bias	Unclear risk	Study authors stated that "The large effect size required by the small number of study sites, which may have resulted in the study being underpowered." There is insufficient information to assess whether an important risk of bias exists.