Participants and study design
Study design: This will be a pragmatic, parallel group, 1:1, superiority, randomized controlled trial, within The Applied Research Group for Kids (TARGetKids!) Practice Based Research Network. TARGetKids! is a primary care research network for children in Toronto, Montreal, and Kingston, Canada. The protocol for this study has been developed in accordance with the SPIRIT Reporting Guidelines.(13)
Inclusion criteria: Young children (18 - 48 months) identified as being at increased risk for childhood obesity will be eligible and invited to participate. The following risk factors, identified in the literature, will be used: a birth weight greater than 3500g(14), weight gain in first year of life (crossing of at least one percentile line of weight-for-length or zBMI percentile)(15) maternal or paternal overweight and obesity (BMI ≥25)(16), gestational smoking(17), and a low median household self-reported income.(18) Availability of at least one parent (caregiver) to participate in the study will be required.
Exclusion criteria: Young children with Prader-Willi syndrome or severe developmental delays, or with obesity or severe obesity will be excluded, as they may require a different intervention; families who are not able to participate in English will also be excluded, as the intervention is only available in English; children with a sibling already enrolled in the study will be excluded to control for confounding variables; and families who reside beyond the Toronto Public Health catchment areas will be excluded from this study, as the intervention is delivered by Toronto Public Health nurses.
Measurements
Eligible participants will be invited to complete questionnaires, physical measurements, accelerometry, and laboratory testing at baseline prior to randomization and at follow-up at 12 months. To comply with public health precautionary measures during the COVID-19 pandemic, if children and parents are unable to attend the primary care setting at enrollment, parents will perform height and weight measurements using standardized equipment with instructions sent to their home. Questionnaires and physical measurements will also be collected at 6 months. Questionnaires include measures of child’s mental health (Strengths and Difficulties Questionnaire), child’s development (Ages and Stages Questionnaire), child’s temperament (Child’s Behaviour Questionnaire), child’s dietary intake (NutriSTEP®), physical activity, sedentary behaviour, sleep duration (Nutrition and Health Questionnaire), direct measure of physical activity, family psychosocial health (Depression, Anxiety, and Parenting Stress), parenting skills (Parenting Scale), and healthcare utilization. Physical measurements include anthropometric measurements to calculate zBMI, and systolic and diastolic blood pressure. Blood samples for cholesterol, insulin, and glucose will be collected at baseline and 12-month follow-up visit. Implementation feasibility and acceptability will be assessed by interviewing parents. Fidelity to the intervention will be assessed using fidelity checklists for all intervention core components, and cost will be collected from study investigators, participants, and administrative datasets.
Clinical Outcome Variables
The primary outcome measure will be the difference in age and sex-standardized BMI z-score at 12-months post-randomization in the intervention and control groups. zBMI will also be measured at 6-months post-randomization. BMI is the key obesity related outcome used in prevention and treatment trials in obesity, and is the Canadian standard for growth monitoring, using the World Health Organization Growth Chart.(19,20) Secondary outcomes will include physical activity, screen time, sleep duration, eating behaviours, family psychosocial health, and cardiometabolic risk (blood pressure, waist circumference, non-HDL, HDL, triglycerides, total cholesterol, glucose, insulin), and mental health outcomes in the children. Sociodemographic measures will be collected via questionnaire. We will examine health care utilization outcomes for children and their mothers through secondary data in partnership with The Institute of Clinical Evaluative Sciences (https://www.ices.on.ca/). For a more detailed overview of all measures, please see Table 1.
Implementation effectiveness outcomes: The feasibility, acceptability, and fidelity outcomes and their corresponding measures for the study are based on a working taxonomy of implementation outcomes.(21) Implementation fidelity will be assessed to capture adherence to the program core components, delivered as intended. A random sample of parents will be interviewed by phone regarding their experience (of the program and implementation).
Health services outcomes: A CEA will be used to determine the incremental costs of the parenting intervention compared to usual care in improving child’s BMI. Using patient level data, the CEA will take a health system perspective and 12- month time horizon. All costs and outcomes will be assigned to the family as the unit of analysis. Direct health care costs including costs of creating and executing the intervention and health services use during the study period will be collected from study investigators and participants. Individual health service utilization will be linked to administrative datasets for those health care visits which are reimbursed by the publicly funded system. Direct patient costs will include out-of-pocket expenses and childcare cost incurred from participating in the intervention. The parenting intervention will be micro-costed and will include all labour and supplies related to creating the program as well as ongoing delivery of the program. Intervention costs will be collected during the study interval and will be allocated across all participants.
Study Procedures
Eligibility and recruitment: Eligible participants will be recruited through the TARGetKids! practice sites in the Greater Toronto Area, Ontario, Canada via research assistants and recruitment flyers and videos. Participants will be asked to complete an informed consent if they choose to participate in the study. They will then complete baseline assessments and will be randomly assigned to the intervention or control group. All parents and children will have follow-up visits at 6-months and 12-months post-intervention by a trained research personnel, and all outcome data will be collected by trained TARGetKids! research staff embedded at each practice site.
Randomization and blinding: Individual children will be randomized based on a stratified randomization technique, ensuring equal recruitment of intervention and control participants for each practice site, executed via computer-generated random allocation sequence, in variable block sizes (i.e., 2, 4, 6). Contamination will be addressed by delivering the parenting group sessions after hours or online, and we will record all participants’ participation in other community-based services. To reduce the risk of bias, research assistants who will not be part of the delivery of the intervention will collect all outcome data, and data analysts will be blinded to group allocation. Parents cannot be blinded to the study allocation; however, they will be blinded that the primary outcome is zBMI.
Intervention: The intervention is composed of eight 2-hour weekly group-based sessions and 4 – 5 coaching visits over a 6-month period. To consolidate learning, 1 – 2 group booster sessions (1 hour each) will be scheduled following completion of the eight parenting group sessions. The intervention curriculum was developed by a multidisciplinary team of experts in child growth and development, health and mental health, parenting, nutrition, and movement behaviours including physical activity, screen time, and sleep. For an overview of the study timeline, please see Figure 1a and 1b.
All intervention components are facilitated by a trained public health nurse. Public health nurses (3) were selected for training and delivery of the intervention by the local public health unit, in consultation with the primary investigator, through an existing collaboration with SickKids Hospital and Toronto Public Health. The nurses were trained in parenting skills, and health behaviours, and had expertise in child obesity prevention and management. For this study, the nurses meet biweekly with the study team to discuss any feedback regarding the intervention. Parenting group session topics will include optimizing healthy behaviours and providing parents with parenting skills training. The parenting skills sessions are based on the Chicago Parent Program, an evidence-based program for parents and children to prevent and treat regulatory problems in young children and promote social, emotional, and academic competence.(22) General parenting topics to be covered will include persistence and emotion coaching; praise and social coaching; routines and rules; limit setting and follow through; and calm-down strategies. Due to the COVID-19 pandemic, all sessions will be delivered virtually over secure video conferencing (i.e., Zoom or Webex).
The coaching visits will be approximately 30 – 40 minutes long and delivered by a public health nurse. The coaching visits will integrate health messages and parenting skills addressed in other intervention components and encourage families to incorporate healthy nutrition and health behaviours individualized for their unique home and family environments through effective parenting practices learned in the program. The public health nurse will also link participants to local community resources where appropriate to support individual child and parental health and mental health identified during the coaching visits; referral will be facilitated by tools such as the Toronto Early Childhood and Family Resource System.(23) Finally, the coaching visits will be used to discuss participant progress, set and monitor personalized goals, and answer any questions. The criteria for a participant to discontinue the intervention is completed through participant request.
Control: The control group children and parents will receive usual care. In Ontario, usual care for this population consists of individual well-child health clinic visits guided by the Rourke Baby Record. Participants in the control group are being offered to participate in future virtual group sessions after the 12 month follow ups are complete.
Data Collection and Management: Trained research assistants will facilitate the collection of questionnaire data, physical measurements, accelerometry data, and blood tests. These questionnaires will be completed on paper or electronically, according to parent preference. REDCap, a secure web-based application will be used to capture data. Non-fasting blood work will be obtained by trained personnel according to the TARGetKids! protocol.(24,25) To address public health measures during COVID-19 pandemic, if children and parents are unable to attend the primary care setting at enrollment, parents will perform height and weight measurements using standardized equipment with instructions sent to their home. Blood tests are only collected if the child attends the clinic visit. All data will be managed through REDCap, which allows for remote web-based data entry directly from the participating sites. REDCap will be managed by the Applied Health Research Centre at the Li Ka Shing Knowledge Institute, St. Michael’s Hospital (Toronto).
Statistical Analysis of Clinical Data
Appropriate descriptive statistics for baseline characteristics (frequencies and proportions for discrete variables; means and standard deviations for symmetric variables; and medians and inter-quartile ranges for skewed data) will be used to compare groups. The principle of intention-to-treat will be applied to the analysis of outcomes. Outcome variables will be compared between arms using ANCOVA with the corresponding baseline measure as the covariate. For the primary outcome, the following additional covariates will be included: age, and each of the risk indicators, (i) birth weight greater than 3500g, (ii) weight gain in first year of life, (iii) maternal or paternal obesity, and (iv) smoking during pregnancy (v) mean family income less than $80,000. Mean differences and corresponding confidence intervals will be calculated. A two-sided level of 0.05 will be applied for the primary outcome. To determine if the treatment effect on the primary outcome depends on baseline BMI, the interaction term between treatment group and baseline BMI will be added to the covariate model. If this term is significant at the 0.1 level, then sub-groups determined by baseline BMI will be examined.
Sample Size
The sample size calculation is based on an ANCOVA for the primary outcome zBMI at 12 months, using the baseline zBMI as a covariate. The total sample size of 108 (54 per arm) is based on the following criteria: A two-sided, level 0.05 test of the null hypothesis of no difference; Power of 0.80; smallest clinically important difference is 0.5 zBMI units at 12 months; between-subject standard deviation is 1 unit; within-subject correlation is 0.638, derived from TARGetKids! dataset of subjects meeting criteria (n>700). Lost-to-follow-up is estimated at 10%.(26,27) Obesity intervention trials in young children with 15-50 children per group have demonstrated significant treatment effect sizes of 0.3-0.5 units of zBMI.(10)
Feasibility and Acceptability: Semi structured interviews will be conducted with parent participants in the intervention and control groups to assess their experiences with the intervention, perceived quality of the intervention, and barriers and facilitators to their participation. Interviews will be recorded, transcribed, and thematic analysis will be conducted.
Fidelity to the core components of the intervention will be measured by the public health nurses following each group session and coaching visit using fidelity checklists and reported using descriptive statistics.
Economic Evaluation Analysis: Cost-effectiveness will be expressed as the incremental cost-effectiveness ratio (ICER) calculated by dividing the incremental costs between the intervention and usual care arms by the incremental change in child’s zBMI between baseline and the end of the follow-up period. A probabilistic analysis using Monte Carlo simulation will be used to establish a point estimate and 95% confidence interval of the ICER. Extensive sensitivity analysis will be used to examine the robustness of the results and evaluate uncertainty in each of the parameters in the analysis. Ranges for the sensitivity analysis will be obtained from 95% confidence intervals generated from study data for each of the parameters. This analysis will be conducted in accordance with guidelines set out by the Canadian Agency for Drugs and Technologies in Health.(28)
Parent Oriented Research Approach
Parents participating in the TARGetKids! network have reviewed and provided feedback on the proposed study protocol and recruitment methods via a Parents’ Panel. (29) The Parents’ Panel was developed to engage parents involved in TARGetKids! research and gather their perspectives on proposed on-going research. The Parent Panel will be engaged throughout the trial to support interpretation of results and knowledge translation.
Knowledge Translation
TARGetKids! is a collaboration between child health researchers, primary care practitioners (paediatricians and family physicians), parents and their children. This study incorporates an integrated knowledge translation approach through continuous engagement with practising primary care clinics and public health nurses in the TARGetKids! network and with parents. At end-of-grant, study findings will be communicated to key knowledge users including parents, health professionals and organizations (primary care physicians and public health practitioners), decision- and policy makers, and other researchers. The research team will actively engage with policy makers early in the execution of the trial to ensure the program is scalable and feasible from a health policy perspective. Reporting of outcomes in peer-reviewed manuscripts will be guided by STaRI standards(30).