The role of socioeconomic background on cardiovascular health promotion in early childhood: insights from the SI Program for preschoolers
Authors: De Cos-Gandoy A , Santos-Beneit G , Bodega P , Baxter J , Diaz-Munoz R , Hill C , Carvajal I , Fernandez-Alvira J M , Fernandez-Jimenez R 
Published: May 2023

Abstract

Funding Acknowledgements
Type of funding sources: Other. Main funding source(s): 1. SHE Foundation and "la Caixa" 2. Fondo de Investigación Sanitaria - Instituto de Salud Carlos III.

Background
Family socioeconomic status (SES) impacts childhood health and could influence the effect of school-based health promotion interventions.

Purpose
This work aims to evaluate the impact of SES on the effects of the SI! Program randomized controlled trials for cardiovascular health promotion in preschoolers carried out in Colombia, Spain, and USA. Specifically, this work analyzed the effect of SES in the change of knowledge, attitudes and habits (KAH) and body mass index z-scores (zBMI) from baseline to immediately after the end of the health promotion intervention.

Methods
Children completed a KAH questionnaire (from 0 to 80 points) at baseline and immediate post-intervention. Families reported household income and education level through a dedicated questionnaire. Household income was categorized as low or high, and education level as low, intermediate, or high based on local census data. Adjusted baseline scores were calculated and stratified by SES using linear mixed models. The impact of the intervention was assessed by an individual participant-level meta-analysis using a random-effects model (DerSimonian-Laird method). Estimates of the difference between groups were derived from linear mixed models.

Results
A total of 3839 children were included in the analysis (48.9% girls, 4.0 (SD=0.8) years at baseline). Children of families with high education level and high household income tended to have a higher KAH score at baseline than those with low education level or low income (47.2 points [95%CI: 43.9; 50.5] vs. 45.7 points [95%CI: 42.4; 48.9]; 47.4 points [95%CI: 44.6; 50.2] vs. 45.8 points [95%CI: 43.0; 48.6], respectively) (Fig. 1A). Children from high education level and high income families had a lower zBMI at baseline than those from low education level and low income families (0.23 [95%CI: -0.20; 0.67] vs. 0.47 [95% CI: 0.03; 0.90]; 0.25 [95%CI: -0.15; 0.66] vs. 0.44 [95%CI: 0.04; 0.85], respectively) (Fig. 1B).
The mean difference in KAH change between the intervention and control groups was 4.76 points (95%CI: 2.78; 6.74). The effect of the intervention on KAH score change was higher for children of families reporting high income or an intermediate/high education level than for those reporting low income or education level (Fig. 2A). The overall mean difference in zBMI change between groups was -0.06 (95%CI: -0.14; 0.02), and no significant differences were found in relation to SES indicators (Fig. 2B).

Conclusions
These results suggest that children from a low SES background benefit less from lifestyle interventions than those from high SES families. Health promotion interventions may implement strategies to counteract this effect and, consequently, avoid the potential risk of increasing health inequalities.