Estimating intervention dose of the multilevel multisite children's healthy living program intervention.

Increased community collective efficacy (CE), defined as social cohesion among neighbors and their willingness to intervene for common good, is associated with improved community health outcomes. However, processes to increase CE and estimate its dose within an intervention are not well understood. The 2 year Children's Healthy Living (CHL) intervention aimed to improve child behaviors known to affect obesity. We used data from CHL to estimate CE dose and examine its association with a successful outcome from CHL-reduction in children's recreational screen time. Monthly reports from nine intervention communities were quantified, and CE dose was calculated for each community overall, at 4 time intervals (6, 12, 18, and 24 months), and for each CE building block-social bonding, social bridging, social leveraging, empowerment, and civic engagement. CE dose at each time interval and change in screen time was correlated using Spearman's rho. Next, communities were categorized as having a high CE dose or a low CE dose, and differences between four high-dose and five low-dose communities were compared using a two-tailed t-test. The correlation between change in screen time and CE dose was significant (rs = 0.83, p = .003). Significantly more activities facilitating empowerment and civic engagement were conducted in high-dose communities, which were more likely to show improvements in screen time, than in low-dose communities. This method of estimating an intervention's CE dose and examining change over time and effect of CE and its building blocks on intervention outcomes shows promise.