O'Connell 2012

Methods	Study design: Cluster‐randomised controlled trial – cross over Funding: “Financial support was provided by the Rudd Foundation.”
Participants	Description: Children aged 3 to 6 years attending 2 private preschools in a small north‐eastern city N (Randomised): 2 preschools (number of children not specified, 96 children recruited) Age: “Age ranged from 3 to 6 years old, but most (85%) children were 4 or 5 years old.” % Female: 44% SES and ethnicity: “These preschools primarily serve highly educated households; nearly all (93%) of the children had at least one parent with a bachelor’s degree and 75% had at least one parent with a graduate or professional degree.” “Race/ethnicity was white (69%), Asian (8%), African American (5%), Hispanic (6%), and other (12%).” Inclusion/exclusion criteria: Not specified Recruitment: Not specified Recruitment rate: Unknown Region: New Haven (USA)
Interventions	Number of experimental conditions: 2 Number of participants (analysed): Intervention = 43, control = 53 Description of intervention: “During the intervention, the children at Preschool A were served one of the new vegetables every day for 30 days in a 3‐day cycle (e.g., Monday, cauliflower; Tuesday, snow peas; Wednesday, green pepper) until they had received each vegetable a total of 10 times.” Duration: 6 weeks Number of contacts: 30 (1 per day for 30 days) Setting: Preschool Modality: Face‐to‐face Interventionist: Teachers Integrity: No information provided Date of study: 2007 Description of control: Control/delayed intervention (Preschool B). “ "Preschool B continued routine practices during the first 6 weeks of the study, and then switched conditions with Preschool A for the second 6 weeks”
Outcomes	Outcome relating to children's fruit and vegetable consumption: Child’s consumption of new vegetables (grams). “Researchers picked up the bags of vegetables later from the schools, weighed them, and calculated intake to the nearest gram.” Outcome relating to absolute costs/cost effectiveness of interventions: Not reported Outcome relating to reported adverse events: Not reported Length of follow‐up from baseline: 12 weeks Length of follow‐up post‐intervention: Immediately Subgroup analyses: None Loss to follow‐up: No loss to follow‐up Analysis: Adjusted for clustering (multilevel modelling) Sample size calculations performed
Notes	Post‐intervention data were extracted following the first phase of the trial (Time 2) prior to cross‐over. As an estimate was not reported for the Time 2 follow‐up that adjusted for clustering, we used post‐intervention data and calculated an effective sample size using ICC of 0.014 to enable inclusion in meta‐analysis. Sensitivity analysis ‐ primary outcome: Fruit or vegetable only outcome reported
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Randomly allocated to experimental group but the random sequence generation procedure is not described
Allocation concealment (selection bias)	Unclear risk	There is no information provided about allocation concealment and therefore it is unclear if allocation was concealed
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Vegetable consumption: Objective measure of child’s vegetable intake and unlikely to be influenced by performance bias
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Vegetable consumption: Objective measure of child’s vegetable intake and unlikely to influence detection bias
Incomplete outcome data (attrition bias) All outcomes	Low risk	There is no reported attrition. Data from 96 children were analysed
Selective reporting (reporting bias)	Unclear risk	There is no study protocol therefore it is unclear if there was selective outcome reporting
Other bias	High risk	Baseline imbalances were reported. There were differences in vegetable consumption at baseline