Rationale and design of the SI! Program for health promotion in elementary students aged 6 to 11 years: a cluster randomized trial

Unhealthy habits in children are increasing at an alarming rate. The school provides a promising setting for effective preventive strategies to improve children's lifestyle behaviors. The SI! Program is a multilevel multicomponent school-based educational intervention aimed at all stages of compulsory education in Spain. Here, we present the design of the SI! Program for Elementary School cluster-randomized controlled trial, targeting children aged 6 to 11 years. This trial aims to study the impact of different timings and intensities of exposure to SI! Program activities on elementary school children and their immediate environment (parents/caregivers, teachers, and school). The trial includes 1770 children from 48 public elementary schools in Madrid (Spain), together with their parents and teachers. Schools and their children were randomly assigned to the intervention group (the SI! curriculum-based educational program over 3 or 6 academic years) or to the control group (standard curriculum). The primary outcomes are the change from baseline at 3-year and 6-year follow-up in children's scores for knowledge, attitudes, and habits (KAH) and health factors (blood pressure, height, weight, waist circumference, and skinfold thickness). Secondary outcomes include 3-year and 6-year changes from baseline in lifestyle questionnaire scores for parents/caregivers and teachers, and in the school environment questionnaire. The overarching goal of the SI! Program is to provide an effective and sustainable health promotion program for the adoption of healthy behaviors in children. The present trial will address the impact and the optimal timing and duration of this educational intervention in the elementary school setting.