Background The Early Intervention Program (EIP) was a 10-week, blended, in-person and online lifestyle intervention for families with children who were off the healthy weight trajectory. The engagement pattern and the dose response of EIP have not been examined. Objective The aims of this paper are to examine families’ engagement patterns with the EIP and to evaluate the dose-response relationship between EIP engagement patterns and physical activity and healthy eating–related outcomes at 10 weeks. Methods Families with children (8-12 years old) who are off the healthy weight trajectory (child BMI ≥85th percentile for age and sex) were recruited. Pre- and postintervention questionnaires assessed child lifestyle behaviors, parental support behaviors, family lifestyle habits, as well as parental physical activity and healthy-eating identity. Hierarchical cluster analysis of both in-person and online components was used to classify engagement patterns. Regression analysis assessed differences in outcomes by engagement groups. Results Two distinct clusters of engagement groups were identified (N=66), which were in-person (IP; n=40, 61%) and in-person + online (IP+; n=26, 39%) engagement. Relative to the IP group at week 10, IP+ showed a greater child moderate-to-vigorous physical activity level (1.53, SD 0.56; P=.008), child physical activity confidence (1.04, SD 0.37; P=.007), parental support for child physical activity (5.54, SD 2.57; P=.04) and healthy eating (2.43, SD 1.16; P=.04), family habits for physical activity (3.02, SD 1.50; P=.049) and healthy eating (3.95, SD 1.84; P=.04), and parental identity for physical activity (2.82, SD 1.19; P=.02). Conclusions The online EIP portal complemented the in-person sessions. Additional engagement with the portal was associated with greater improvements in child physical activity and parental support behaviors, habits, and identity for physical activity.

BACKGROUND The Early Intervention Program (EIP) was a 10-week blended in-person and online lifestyle intervention for families with children who were off the healthy weight trajectory. The engagement pattern and the dose-response of EIP have not been examined. OBJECTIVE 1) To examine families' engagement patterns with the EIP; 2) To evaluate the dose-response relationship between EIP engagement patterns and physical activity and healthy eating-related outcomes at 10-weeks. METHODS Families with children who are off the healthy weight trajectory (child BMI ≥ 85th percentile for age and sex) were recruited. Pre-and post-intervention questionnaires assessed child lifestyle behaviours, parental support behaviours, family lifestyle habits and parental physical activity and healthy eating identity. Hierarchical cluster analysis of both in-person and online components was used to classify engagement patterns. Regression analysis assessed differences in outcomes by engagement groups. RESULTS Two distinct clusters of engagement groups were identified: in-person (IP, n=40) and in-person + online (IP+, n=26) engagement. Relative to the IP group at week 10, IP+ showed a greater child moderate-to-vigorous physical activity level (1.53 ±0.56, p=.008), child physical activity confidence (1.04 ±0.37, p=.007), parental support for child physical activity (5.54 ±2.57, p=.035) and healthy eating (2.43 ±1.16, p=.041), family habits for physical activity (3.02 ±1.50, p=.049) and healthy eating (3.95 ±1.84, p=.036), and parental identity for physical activity (2.82 ±1.19, p=.021). CONCLUSIONS The online EIP portal complemented the in-person sessions. Additional engagement with the portal was associated with greater improvements in child physical activity and parental support behaviours, habits, and identity. CLINICALTRIAL n/a