Table 3.
Summary of key design elements in the COPTR Trials
| Minnesota | Vanderbilt | Stanford | Case Western Reserve | |
|---|---|---|---|---|
| Design | 2 arm IRGT (I vs. C) with small groups in I only | 2 arm IRGT (I vs. C) with small groups in I (weight) and C (literacy) | 2 arm RCT (I vs. C) with mix of individual, family and non-fixed group interventions in I (weight) and C (active placebo) | 3 arm IRGT (I #1 andI #2 vs. C) with small groups in two arms (I #1 and I #2) crossed with 2 arm NRGT (I vs. C) |
| Intervention channels | Intervention aimed at parents via family connector home visitation programs and parenting classes at community centers to improve and reinforce healthy dietary patterns, and promote physical activity. | Intervention aimed at parents and children in classes at community centers. It includes social media and phone coaching to improve dietary patterns, and use of the built environment to enhance physical activity of parent and child. | Intervention aimed at youth and parents in home-based intervention to reduce screen time, increase physical activity and alter dietary practices; community-based after school team sports, and primary care counseling. | Intervention aimed at youth and parents in small group sessions and at youth in school-based activities through a series of goal setting, skills building, changes in the family environment and daily routines to improve diet and physical activity patterns. |
| Eligibility | BMI>= 50th percentile | 50th percentile<=BMI<95th percentile (may consider≥ 45th percentile and<99th percentile) | BMI >= 85th percentile for age and sex | BMI >= 85th percentile for age and sex |
| Randomization | A priori stratification by age (2,3,4) and sex (girl, boy) | A priori stratification by language preference (English, Spanish) | A priori stratification on BMI percentile category (overweight, obese) | A priori stratification by weight status, blood pressure status, and gender |
| Age group | 2–4 yrs at baseline | 3–5 yrs at baseline | 7–11 yrs at baseline | 10–13 yrs at baseline |
| Analysis | Mixed model | Mixed non-linear model | Two-stages: individual slopes in first stage, ANCOVA in second stage | Two stages; individual slopes in first stage, ANCOVA in second stage |
| Retention | Expect to retain 75%–85% at 24 and 36 months. | Expect to retain 80% at 36 months | Expect to retain > 85% at 36 months | Expect to retain 70% at 36 months |
| Missing data | Assumed MAR based on experience from earlier studies with similar outcome (weight) showing no differential loss to follow-up associated with baseline measures | Assumed MAR or MCAR. Will consider NMAR in secondary analyses. | Assume MAR after conditioning on baseline BMI and other baseline values. Will consider multiple MAR models and multiple NMAR models in secondary analyses. | Assumed MAR. Will consider NMAR in secondary analyses. |
| Imputation | Missing data will be considered in secondary analyses | Missing data will be considered in secondary analyses | Missing data will be considered in primary analysis | Missing data will be considered in secondary analyses. |
| Effect size expected | 0.3 sd units for means at 24 or 36 months | 0.4sd units for quadratic term | 0.4 sd units for slopes | 0.4 sd units for slopes |
*
C is control; I is intervention; IRGT is individually randomized group-treatment trial; MAR is missing at random; MCAR is missing completely at random, NMAR is not missing at random; NRGT is a non-randomized group trial; RCT is randomized controlled trial. Details are available in the separate papers for each study presented elsewhere in this issue.