Replicability, adaptability and long-term impact of the 'Healthy Youngsters, Healthy Dads' program in Newcastle, Australia.

'Healthy Youngsters, Healthy Dads' (HYHD) targets fathers to improve the health of their preschool-aged children. In a previous randomized trial, fathers and children experienced meaningful improvements in physical activity and eating behaviours. The next phase is to test the replicability and adaptability of HYHD when delivered in the community by trained facilitators. Fathers/father-figures and children aged 3-5 years were recruited from Newcastle, Australia into a 9-week, non-randomized trial with assessments at baseline, 10 weeks, and 12 months. The primary outcome was achievement of pre-registered targets for recruitment (≥ 96 dyads), attendance (≥ 70%), compliance (completing ≥ 70% of home-based tasks), fidelity (≥ 80% of content delivered as intended) and program satisfaction (≥ 4/5). Secondary outcomes included physical activity, nutrition, screen time and parenting measures. Process targets were surpassed for recruitment (140 fathers, 141 children), attendance (79% for fathers-only workshops, 81% for father-child sessions), compliance (80% of home-tasks completed), fidelity (99% for education, ≥ 97% for practical) and program satisfaction (4.8/5). Mixed effects regression models revealed significant effects in fathers for moderate-to-vigorous physical activity, co-physical activity, dietary intake and parenting practises, which were maintained at 12 months. Significant effects were also established for screen time at 10 weeks only. For children, significant effects were observed for screen time and dietary intake at 10 weeks, while effects on energy-dense, nutrient-poor foods and healthy, nutrient-dense core food intake were maintained at 12 months. Findings demonstrate the replicability and adaptability of HYHD when delivered in the community by local trained facilitators. Further investigation into how to optimally scale-up HYHD is warranted.