Kirks 1982a.

Methods	Study design: cluster‐randomized controlled trial Study grouping: parallel group Study aim: "... to assess the effects of a parent nutrition education program on nutrition education outcomes in young children" (quote) Study period: 1979‐1980 school year Total number of arms: 3 Description of intervention arms: 1. School‐based intervention for children with concurrent parent education (child + caregiver); 2. School‐based intervention for children (child only); 3. No intervention control (not eligible) Number of clusters per arm: 1 Average cluster size: 140.33 children Sample size justification and outcome used: not reported Unit of allocation: school Missing data handling: the number of cases for each outcome differed due to missing data. This suggests that pair‐wise deletion was used rather than list‐wise deletion (i.e. complete case analysis) Reported limitations: 1. Small sample size and non‐random distribution of student ability limits generalizability Randomization ratio and stratification: 1:1:1; effort to match by socioeconomic status, location, quality of teachers and staff, and similarity of resources Participant compensation or incentives: none provided
Participants	Baseline characteristics Child + caregiver arm (intervention group) Female (PROGRESS‐Plus): not reported Age in years (PROGRESS‐Plus): not reported Race/ethnicity/language/culture (PROGRESS‐Plus): not reported Place of residence (PROGRESS‐Plus): not reported Caregiver education (PROGRESS‐Plus): not reported Religion (PROGRESS‐Plus): not reported Household income/socioeconomic status (PROGRESS‐Plus): not reported Social capital (PROGRESS‐Plus): not reported Caregiver work hours and other characteristics that may indicate disadvantage (PROGRESS‐Plus): not reported Disability (PROGRESS‐Plus): not reported Sexual orientation (PROGRESS‐Plus): not reported Child weight status: not reported Child diet: not reported Child physical activity: not reported Caregiver weight status: not reported Caregiver diet: not reported Caregiver physical activity: not reported Caregiver civil status (PROGRESS‐Plus): not reported Child‐only arm (control group) Female (PROGRESS‐Plus): not reported Age in years (PROGRESS‐Plus): not reported Race/ethnicity/language/culture (PROGRESS‐Plus): not reported Place of residence (PROGRESS‐Plus): not reported Caregiver education (PROGRESS‐Plus): not reported Religion (PROGRESS‐Plus): not reported Household income/socioeconomic status (PROGRESS‐Plus): not reported Social capital (PROGRESS‐Plus): not reported Caregiver work hours and other characteristics that may indicate disadvantage (PROGRESS‐Plus): not reported Disability (PROGRESS‐Plus): not reported Sexual orientation (PROGRESS‐Plus): not reported Child weight status: not reported Child diet: not reported Child physical activity: not reported Caregiver weight status: not reported Caregiver diet: not reported Caregiver physical activity: not reported Caregiver civil status (PROGRESS‐Plus): not reported Recruitment methods: not reported Inclusion criteria: cluster: not reported; participants: kindergarten, first, second, or third grade students and caregivers Exclusion criteria: not reported Age of participating children at baseline: kindergarten to third grade (estimated to be 4 to 9 years old) Total number randomized by relevant group: total across all study arms: n = 421; child + caregiver arm: n = 176; child‐only arm: n = 140 Baseline imbalances between relevant groups: not reported Total number analyzed by relevant group: dietary outcomes (child + caregiver arm: n = 51; child‐only arm: n = 50) Attrition by relevant group: attrition rates were calculated by dividing the number of children without dietary intake data at the post‐test assessment by the number of participating children in each study arm: child + caregiver arm: 71.0% (125/176); child‐only arm: 64.3% (90/140) Description of sample for baseline characteristics reported above: not reported
Interventions	Intervention characteristics Child + caregiver arm (intervention group) Brief name/description (TIDieR #1): school‐based nutrition education curriculum with concurrent parent education Focus of intervention: diet Behavior change techniques: in addition to the child‐only intervention, the following techniques were applied separately or differently in the child + caregiver arm: "feedback and monitoring," "social support," "shaping knowledge," "comparison of outcomes" Why: rationale, theory, or goal (TIDieR #2): parent‐focused nutrition education may "help children transfer nutrition knowledge to food choice behavior" (quote). The objectives of the parent education component included “stimulating the benefits of good nutrition, providing information conducive to good nutritional practices, and encouraging parent‐child interaction relevant to selecting nutritious foods” (quote). Study authors did not describe the use of theory in development of this intervention How, where, and when and how much (TIDieR #6 to 8): in addition to the child‐only arm, biweekly newsletters with nutrition information were sent home for parents, and parents had access to a dietitian 5 days a week Who: providers (TIDieR #5): in addition to classroom teachers (who delivered the school nutrition education curriculum), intervention components were provided by project staff, including a dietitian Economic variables and resources required for replication: not reported Strategies to address disadvantage: not reported Subgroups: same as child‐only arm Assessment time points: baseline, 4 months (end of intervention), 5 years (follow‐up) Co‐interventions: not reported What: materials and procedures (TIDieR #3 to 4): in addition to the child‐only arm, nutrition topics in the newsletters were selected based on interest questionnaires completed by parents before program implementation. Additional topics "deemed important to development of positive food choice behaviors" (quote) were incorporated by project staff. Parents also had family menus analyzed for nutrition content and access to a dietitian for dietary counseling and to answer questions about food, nutrition, and health Tailoring (TIDieR #9): the content of nutrition education for caregivers was based mostly on parents' interests as reported in an initial survey Modifications (TIDieR #10): not reported How well: planned and actual (TIDieR #11 to 12): not reported Sensitivity analyses: not reported Child‐only arm (control group) Brief name/description (TIDieR #1): school‐based nutrition education curriculum Focus of intervention: diet Behavior change techniques: "shaping knowledge" Why: rationale, theory, or goal (TIDieR #2): prior research suggests that nutrition education programs improve nutrition knowledge, but impact on diet remains unclear. Study authors did not describe the use of theory in development of this intervention How, where, and when and how much (TIDieR #6 to 8): children received weekly nutrition education in class over a 4‐month period Who: providers (TIDieR #5): classroom teachers, who received 15 hours of in‐service training on the principles of nutrition and use of the curriculum guide Economic variables and resources required for replication: not reported Strategies to address disadvantage: not reported Subgroups: analyses for nutrition knowledge and attitudes were done separately for each grade level Assessment time points: baseline, 4 months (end of intervention), 5 years (follow‐up) Co‐interventions: not reported What: materials and procedures (TIDieR #3 to 4): nutrition education lessons were "based on the conceptual framework for nutrition education in schools suggested by the White House Conference on Food, Nutrition and Health" (quote) Tailoring (TIDieR #9): not reported Modifications (TIDieR #10): not reported How well: planned and actual (TIDieR #11 to 12): teachers were interviewed weekly to ensure that equal time was allocated to the nutrition education lessons in all schools Sensitivity analyses: not reported
Outcomes	The following instruments were used to measure outcomes relevant to this review at baseline, 4 months (end of intervention), and 5 years Children's dietary intake and dietary quality: parent‐reported food frequency questionnaire querying the number of servings of each of several listed food categories consumed during a 24‐hour period Data were used to calculate children's intake of selected food groups, including fruit intake and vegetable intake, as well as dietary quality and dietary diversity. However, data reported for both assessments exclude a measure of variance, and this information could not be retrieved from the study authors
Identification	Study name: not reported Country: USA Setting: northern California Types of reports: published journal articles Comments: used the following reports: (1) Kirks 1982b, (2) Kirks 1986, as well as unpublished information provided by the study authors (Fischer 2019 [pers comm]) Author's name: Barbara A Kirks Email: not available Conflicts of interest: not reported. However, the study authors noted, "the first author has been the ongoing nutrition consultant for the school district in which our study was done" (quote) Sponsorship source: California State Department of Education
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation	Unclear risk	Quote: "…three schools were matched and randomly assigned to one of three groups" (Kirks 1986, p 203) Judgement comment: however, the method used to generate the random sequence was not reported
Allocation concealment	Unclear risk	Judgment comment: methods used to conceal the allocation sequence were not described
Blinding of participants and personnel All outcomes	Low risk	Judgment comment: no information on blinding of participants and personnel was provided. However, given the nature of the intervention, there would have been no way to blind participants and personnel. Also, the children were aged approximately 4 to 9 years, so their performance was not likely to have been influenced by lack of blinding
Blinding of outcome assessment All outcomes	Unclear risk	Judgment comment: no information on blinding of outcome assessors was provided. Dietary intake was reported by caregivers, and outcomes may or may not have been influenced by lack of blinding
Incomplete outcome data All outcomes	High risk	Judgment comment: we calculated attrition rates by dividing the number of children without dietary intake data at the post‐test assessment by the number of participating children in each study arm. Total attrition was 35.9% (151/421) for the study overall and 68.0% (215/316) for the 2 relevant study arms. Differential attrition for the relevant study arms was 6.7% (125/176 vs 90/140). Dietary data were not collected at baseline, and analyses considered only children with data at the post‐test assessment (or, for the follow‐up assessment, only children with data at the 5‐year follow‐up time point)
Selective reporting	High risk	Judgment comment: the trial was not registered and no protocol was cited that could be retrieved. Fruit intake, vegetable intake, dietary diversity, and dietary quality outcomes were reported incompletely and could not be entered into the meta‐analysis. We could not retrieve relevant data from the study authors
Recruitment bias	Unclear risk	Judgment comment: it is unclear whether participants were recruited before or after randomization
Baseline imbalance	High risk	Judgment comment: study authors did not report on similarities and differences between intervention arms. However, the study authors noted that one of the classes involved in the study was "exceptional" (quote; Kirks 1982b, p 139), and it would have been better if the treatment groups were truly matched
Loss of clusters	Low risk	Judgment comment: this is not relevant because there was only 1 cluster per arm
Incorrect analysis	High risk	Judgment comment: study authors did not report adjusting for clustering in the analysis and did not report intraclass correlation coefficients (ICCs)
Comparability with individually randomized trials	Unclear risk	Judgment comment: information was insufficient to permit judgment
Other sources of bias	High risk	Judgment comment: only 1 cluster was reported per intervention arm