Hard Lessons From a School-Based Intervention to Improve Cardiovascular Health in Adolescence

Adolescence is a critical period for the prevention of cardiovascular diseases (CVDs). Cardiovascular health (CVH) is a concept introduced in 2010 by the American Heart Association that uses a positive paradigm to measure, monitor, and modify CVD risk. This measurement combines 4 health risk factors (body mass index, blood pressure, total cholesterol level, and fasting blood glucose level) and 3 health behaviors (smoking, physical activity, and diet) into 1 score, ranging from 0 to 14.¹ Research has shown that people who maintain high CVH levels from adolescence onward live longer, healthier lives free of major CVD risk factors and multiple chronic comorbidities. Youth who maintain higher CVH levels have a lower risk of developing premature CVD in adulthood and very low mortality rates over 32 years.² In fact, it is estimated that if everyone had high CVH levels in late adolescence or young adulthood, the vast majority of cardiovascular events would be avoided.² Unfortunately, very few people have high levels of CVH. Longitudinal analyses have shown that CVH is highest in people of younger ages and decreases gradually throughout the life course. Given that prospective cohort studies have found the greatest CVH decrease occurs around age 17 years,³ interventions that slow or reverse this loss in adolescence are especially needed.

In this issue of JAMA Cardiology, Santos-Beneit and colleagues⁴ report the primary results of the Salud Integral, or SI! Program, a cluster randomized clinical trial of a school-based intervention to improve the CVH of adolescents. The investigators developed a theoretically informed health promotion curriculum to foster healthy eating, physical activity, emotional regulation, and avoidance of tobacco and other substances. The primary curriculum was delivered by classroom teachers over either 2 years (short-term) or 4 years (long-term) and included additional components to improve the adolescents’ environment delivered to families and school administrators. The investigators enrolled and randomized 1326 adolescents by 24 schools into short-term, long-term, or standard curriculum arms. The primary end point was the 14-point American Heart Association CVH score assessed at the 2- and 4-year follow-up.

Adolescents in the long-term program demonstrated an improvement in total CVH score and a mean CVH score that was 0.44 points (95% CI, 0.01–0.87) higher than the CVH score of the control arm at the 2-year follow-up. Unfortunately, CVH scores did not differ significantly between the 3 arms at the 4-year follow-up. Mean CVH scores decreased for all arms by the study’s conclusion—consistent with the well-described decrease in CVH during this time in the life course³—with the biggest decreases in nonsmoking status and physical activity. Promising improvements in some of the other CVH metrics were seen but did not differ significantly across the study arms at the conclusion of the study.

There were many factors that could have hindered the efficacy of this school-based program. The final 2 years of the study occurred during the COVID-19 pandemic. Undoubtedly, the global lockdown compromised the delivery of the intervention and introduced many measured and unmeasured challenges to students, teachers, and the study team. The intervention for the long-term arm was adapted for remote implementation but faced important limitations on the delivery of the physical activity modules. In addition, technological issues were documented with the gamification platform created for the study, along with teachers’ negative attitude to-ward digital technologies.

Despite the nonsignificant changes reported, this study introduced important insights that can inform future implementation efforts. The authors used a positive youth development approach to encourage adolescents to draw upon their developmental assets when choosing healthy behaviors. Positive youth development fosters adolescents’ competence, confidence, character, connection, and caring for others and can be maximized by inviting adolescents to cocreate behavioral interventions with scientists. A successful example of this is the truth Campaign, which engages adolescents to create antitobacco messages that highlight their role in resisting the deceptive advertising of tobacco companies.⁵

Implementation research frameworks highlight the need to engage key stakeholders not only on the evaluation, but rather, from the beginning when designing an intervention, setting goals, and determining the modes of administration. Better understanding the motivations, needs, and implementation barriers that teachers and adolescents face could yield better long-term outcomes in future studies. While the authors drew upon the social ecologic model to influence the food and built environment of adolescents through parents and school administrators, successful interventions will likely need to reach beyond these immediate environments. Policies that support equitable access to higher education, quality housing, and employment, and that use incentives to regulate the production and purchase of unhealthy food and tobacco products, are needed to make “the healthy choice the easy choice.”⁶

An inevitable conclusion is that comprehensive school-based interventions may be insufficient when seeking to improve the CVH of youth. We must acknowledge that interventions need to target multiple levels of the socioecologic system, where people learn, live, work, and play. The increasingly early onset of major CVD risk factors, including obesity, hypertension, diabetes, and high blood cholesterol levels, urgently requires effective, sustainable, and multilevel interventions that support the maintenance and improvements of CVH from adolescence into adulthood. Continued research, evaluation, and learning from both successes and failures will contribute to the development of more effective interventions that can positively impact youth’s CVH. While the lack of improvement in total CVH in the Si! Program is disappointing, it is important to remember that even small changes in CVH or a slowing of CVH decline with age can translate into fewer CVD events later in life.⁷ It is critical that we persist in the quest to improve the cardiovascular health of children and adolescents. The health of this and future generations to come depends on it.