Prevention of Childhood Obesity in Child Health Services: Follow-Up of the PRIMROSE Trial

Background: Childhood obesity is an urgent public health concern, and there's a need for long-term, high-quality, primary prevention trials targeting parents of young children. The aim of the current study was to evaluate the long-term effect of a parental support program based on motivational interviewing (MI). Methods: A cluster randomized controlled trial was carried out in eight Swedish counties. Participating families (N=1355) were enrolled when the child was 9 months old, and participated in nine sessions during similar to 39 months. The aim was to pomote healthy food and physical activity (PA) habits using MI and principles from cognitive behavioral therapy. Nurses in Swedish child health services delivered the intervention, and the control group received usual healthcare. The current study was a 1-year follow-up of effects on children's weight-related measures. Regression analyses were conducted using generalized estimating equations, including analyses to investigate potential parental moderators of the effect. Results: There were no statistically significant intervention effects at follow-up [BMI difference=-0.13, p=0.29, overweight relative risk (RR)=0.96, p=0.78, obesity RR=0.57, p=0.20]. Maternal waist circumference and unhealthy eating and paternal PA moderated the effect, but effects were small and failed to reach statistical significance after correction for multiple comparisons. Conclusions: A parent-focused primary prevention intervention based on MI delivered within child health services did not result in effects at 1-year follow-up. The results were in line with those obtained at post-assessment and indicated no late onset of effect. Further studies exploring individual and contextual factors influencing the outcome are called for.