Evaluating the contribution of a scaled up community-based overweight prevention programme in the Netherlands to children's health behaviours and BMIz.

Background: Community-based overweight prevention programmes are widely implemented, however, little is known about their effectiveness after scale-up. This study examines the contribution of a scaled up community-based overweight prevention programme in the Netherlands: Healthy Youth, Healthy Future (JOGG) to children's BMIz, adherence to fruit and/or vegetable consumption guidelines, and minutes of moderate to vigorous physical activity (MVPA) per week.

Methods: In this observational study we used repeated cross-sectional data from 5 to 11- and 12-18-year-old participants in the annual Dutch national health survey (2006-2019) and applied two analytical methods for more robust inference. First, we applied linear mixed models to assess the association between JOGG exposure for at least 18 months (n = 1,008) vs. no exposure (n = 23,779) and the outcomes and assessed whether this association differed across subgroups defined by age, socioeconomic position (SEP), or migration background. Second, we compared outcome trends in JOGG and non-JOGG municipalities before and after implementation, using a difference-in-differences approach, to account for unobserved time-invariant confounders.

Results: Results showed no significant association between JOGG exposure and BMIz or MVPA. However, JOGG exposure was associated with higher adherence to fruit and/or vegetable consumption guidelines in 12- to 18-year-olds (log odds 1.82, 95%CI 0.23, 3.41). We observed no differential associations across subgroups and no differences in outcome trends between JOGG and non-JOGG municipalities.

Conclusions: The scale up of JOGG in the Netherlands between 2010 and 2019 potentially contributed to higher fruit and vegetable consumption but not to BMIz or MVPA levels. Further examination of the implementation process may provide insight in underlying mechanisms and contribution of JOGG.