Design of the School-Based SI! Program Reintervention Trial for Child Health Promotion

The SI! Program is a long-term, school-based intervention promoting cardiovascular health across multiple age groups. This article presents the design of a new cluster-randomized controlled trial incorporating a reintervention to strengthen sustainability and promoting a school-family approach. A total of 977 children (age 6.2 years, 51.6% girls) from 50 schools in Spain were recruited. Schools were randomized to a reintervention group (intervention in second grade and reintervention in fifth grade) or a single-intervention group (intervention only in fifth grade). The primary endpoint is the change in the SI!-Child score-diet, physical activity, sleep health, and body mass index-between baseline and 5-year follow-up. The secondary endpoints include 5-year changes in SI!-Child subcomponents, sedentarism, adiposity, and the Life's Essential 8 score and subcomponents. This revised SI! Program builds on insights from earlier trials, emphasizing adherence and long-term behavior change through a reintervention combined with active engagement of the school community and families. (The SI! Program Reintervention for Elementary Schools Trial [PSIR]; NCT06715358).