Yeh 2018.

Study characteristics
Methods	Study design: cluster‐RCT Length of follow‐up from baseline: 7 months Unit of allocation: preschool (Head Start programmes) Unit of analysis: child
Participants	Service type: centre‐based (Head Start) Operation: half day program Country (region): USA (Midwestern metropolitan area) Country income classification: high Low‐SES sample: yes Population description: this study took place at the United Children and Family Head Start programmes in a major Midwestern metropolitan area. African American preschool children comprised 95% of the population in the half‐day programme. 6 Head Start programmes, each with a morning and an afternoon session, participated in the study. Inclusion criteria: the participants were preschoolers with ages ranging between 3 and 5 years old. Exclusion criteria: not reported Number of services randomised: 6 (2 intervention 1, 2 intervention 2, 2 control) Number of children randomised: 160 (47 intervention 1, 54 intervention 2, 59 control) Characteristics Children Age: 3‐5 years Gender (% female): Intervention 1: 49% Intervention 2: 41% Control: 44% Ethnicity: not reported Parents Age (years): not reported Gender (% female): not reported Ethnicity: not reported Parent/family SES: not reported Method of recruitment: not reported Missing data/dropout: not reported Reasons for dropout: not reported Characteristics of dropouts: not reported
Interventions	Programme name: Healthy Kids Healthy Lives Number of conditions: 2 interventions, 1 control Intervention duration: 7 months Intervention setting: ECEC Intervention strategies: Intervention 1: Group A Health curriculum Children Education: children received 30‐min nutrition education sessions 2 x/week, for 7 months, provided by dietetic interns under the supervision of a registered dietitian. The content included the introduction of healthy "body building" foods and discussion of food groups. Hand puppets in the form of vegetables or fruits were used to introduce the content. Ethos and environment Children Exposure: fresh fruit and vegetable tastings included in the nutrition education session Service Menu modification: wholegrain products were substituted for products usually made with white flour. Support: researchers worked with the food provider from each centre and purchased the required amount of wholegrain products based on the service menu from local grocery stores. Meetings: before commencement of this study, the researchers met once with the food service provider centres and went over the food substitution plan and encouraged them to use all the wholegrain products provided and follow the recommended menu and recipes/cooking method. Monitoring: researchers emphasised the food substitutions and monitored use of the foods during weekly high‐fibre food delivery. Partnerships Healthcare Delivery: dietetic interns delivered nutrition education. Intervention 2: Group B Health curriculum Children Education: children received 30‐min nutrition education sessions 2 x/week, for 7 months, provided by dietetic interns under the supervision of a registered dietitian. The content included the introduction of healthy "body building" foods and discussion of food groups. Hand puppets in the form of vegetables or fruits were used to introduce the content. Ethos and environment Children Exposure: fresh fruit and vegetable tastings included in the nutrition education session. Service Menu modification: wholegrain products were substituted for products usually made with white flour. Support: researchers worked with the food provider from each centre and purchased the required amount of wholegrain products based on the service menu from local grocery stores. Meetings: before commencement of this study, the researchers met once with the food service provider centres and went over the food substitution plan and encouraged them to use all the wholegrain products provided and follow the recommended menu and recipes/cooking method. Monitoring: researchers emphasised the food substitutions and monitored use of the foods during weekly high‐fibre food delivery. All participants Cultural: the nutrition education was culturally‐appropriate (tailored to the African‐American, Midwest, Head Start‐eligible study population). Partnerships Families Lecture: caregivers received a 1‐h nutrition lecture every month. Classes were taught by dietetic interns and held in the 2 centres. The classes included 20‐min presentation followed by group discussion and interactive activities related to the topic. Healthcare Delivery: dietetic interns delivered family lectures and nutrition education. Intensity of intervention: Intervention 1: 2 x 30‐min child nutrition education/week, over the course of 2 semesters (7 months) Intervention 2: 2 x 30‐min child nutrition education/week, over the course of 2 semesters (7 months); 1‐h caregiver group nutrition classes every month. Intervention delivered by: Intervention 1: research team, ECEC staff, healthcare staff Intervention 2: research team, ECEC staff, healthcare staff Modality: Intervention 1: face‐to‐face, written Intervention 2: face‐to‐face, written Theoretical basis: not reported Description of control: usual care
Outcomes	Outcomes relating to child dietary intake: not reported Outcomes relating to child physical measures: BMI percentile Number of participants analysed: Intervention 1 baseline: 47 Intervention 1 follow‐up: 47 Intervention 2 baseline: 54 Intervention 2 follow‐up: 54 Control baseline: 59 Control follow‐up: 59 Data collection measure: objectively measured (CDC) Data collector: not reported 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: a grant from the Office of the Vice President for Research, Wayne State University.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	The 6 participating schools were randomly assigned to one of 3 groups with 2 schools per group. The sequence generation procedure was not described.
Allocation concealment (selection bias)	Unclear risk	No information on the method of allocation concealment reported.
Blinding of participants and personnel (performance bias) Physical outcomes	Low risk	No blinding of participants and personnel to 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 measured by train graduate students and were not likely to be influenced by lack of blinding.
Incomplete outcome data (attrition bias) Physical outcomes	Unclear risk	Study authors stated that "A convenience sample of 203 preschooleres was recruited at baseline. Post‐intervention data collection occurred 7 months later and included 164 preschoolers who completed the Head Start program during the academic year (80% retention)." Reasons for missing data and differences between treatment groups are not reported. Risk of attrition bias is unclear.
Selective reporting (reporting bias)	Unclear risk	No prospective trial protocol or trial registration so it was unclear whether there was selective outcome reporting.
Recruitment bias	Unclear risk	It is unclear whether individuals were recruited to the study before or after randomisation of clusters.
Baseline imbalance	Unclear risk	Only BMI was considered so there is insufficient information to assess whether bias exists. At baseline, there was no difference in BMI among the 3 groups. The control group had a higher mean BMI percentile than the intervention groups but the difference was nonsignificant (P = 0.067). No significant differences were found when comparing mean BMI and BMI percentiles from baseline to postintervention among the 3 groups.
Loss of clusters	Unclear risk	Not reported
Incorrect analysis	High risk	There was no accounting for clustering of children within Head Start centres.
Contamination	Unclear risk	No evidence to make assessment.
Other bias	Unclear risk	The study may have been underpowered. Study authors stated that "It is speculated that if the sample size is increased, the significant reduction in BMI percentile in group A may become apparent." There is insufficient information to assess whether an important risk of bias exists.