Ripple Effects of a Community-Based Randomized Trial for Rural Women: Strong Hearts, Healthy Communities.

Objective: This study aimed to examine (1) whether the Strong Hearts, Healthy Communities intervention (SHHC) improved social network members' (SNMs') weight, exercise, and diet and (2) whether SNMs' weight and behavioral changes were modified by their relationship closeness and/or spatial closeness with trial participants.

Methods: Eight towns received the SHHC intervention, which focused on building individual healthy behaviors and creating supportive social and built environments for exercise and healthy eating. Eight towns received an education-only control intervention. SNMs (n = 487) were recruited to complete a questionnaire at baseline and at 6 months that asked about demographics, weight, height, exercise, and eating habits.

Results: SHHC's effect on SNMs differed depending on their relationship closeness with trial participants. Among SNMs who had a very close relationship with trial participants, those associated with the intervention group lost more weight and decreased BMI more than those associated with the control group (weight [kilograms] between-group difference: Δ = -1.68; 95% CI: -3.10 to -0.25; P = 0.021; BMI between-group difference: Δ = -0.60; 95% CI: -1.16 to -0.04; P = 0.034). Spatial closeness did not modify any of SHHC's ripple effects.

Conclusions: Relationship closeness, rather than spatial closeness, played an important role in influencing a rural community-based intervention's ripple effects.