Effectiveness of an mHealth- and School-Based Health Education Program for Salt Reduction (EduSaltS) in China: Cluster Randomized Controlled Trial Within Scale-Up.

Abstract

Background: Globally, cardiovascular diseases are leading causes of mortality and disability, with hypertension being a major risk factor. Reducing salt intake and blood pressure are among the most cost-effective health promotion strategies. While mobile health (mHealth)- and school-based salt reduction interventions have proven effective in trials, their impact when scaled up in real-world contexts remains uncertain.

Objective: We evaluated the effectiveness of the real-world implementation of an mHealth- and school-based health education scale-up program to reduce salt intake (EduSaltS [mHealth and school-based education program to reduce salt intake scaling up in China]).

Methods: A parallel cluster randomized controlled trial was conducted from April 2022 to July 2023 across 20 schools in 2 districts and 2 counties within Ganzhou City, Jiangxi Province, China. Schools were randomized 1:1 to intervention or control groups within each district or county. One third-grade class per school and 26 students per class were randomly sampled. One parent, or alternative family member (aged 18-75 years, residing with the student), of each student was invited to join. The EduSaltS intervention, spanning over 1 academic year, incorporated both app-based health education courses and offline salt reduction activities, with participation monitored through the backend management system. The intervention's effectiveness was assessed by comparing changes in salt intake and blood pressure between groups from baseline to 1-year follow-up using surveys, physical examination, and 24-hour urine tests.

Results: Of 524 children (boys: n=288, 54.96%; age: mean 9.16, SD 0.35 years) and 524 adults (men: n=194, 37.02%; age: mean 40.99, SD 11.04 years) who completed the baseline assessments in 10 intervention and 10 control schools, 13 (2.48%) children and 47 (8.97%) adults were lost to follow-up. All schools and participants showed satisfactory intervention adherence. Measured differences in schoolchildren's salt intake, systolic blood pressure, and diastolic blood pressure, between the intervention and control schools, were -0.24 g/day (95% CI -0.82 to 0.33), -0.68 mm Hg (95% CI -2.32 to 0.95), and -1.37 mm Hg (95% CI -2.79 to 0.06), respectively. For adults, the intervention group's salt intake decreased from 9.0 (SE 0.2) g/day to 8.3 (SE 0.2) g/day post intervention. Adjusted changes in the intervention (vs control) group in salt intake, systolic blood pressure, and diastolic blood pressure were -1.06 g/day (95% CI -1.81 to -0.30), -2.26 mm Hg (95% CI -4.26 to -0.26), and -2.33 mm Hg (95% CI -3.84 to -0.82), respectively.

Conclusions: The EduSaltS program, delivered through primary schools with a child-to-parent approach, was effective in reducing salt intake and controlling blood pressure in adults, but its effects on children were not significant. While promising for nationwide scaling, further improvements are needed to ensure its effectiveness in reducing salt intake among schoolchildren.

Trial registration: Chinese Clinical Trial Registry ChiCTR2400079893; https://tinyurl.com/4maz7dyv (retrospectively registered); Chinese Clinical Trial Registry ChiCTR2000039767; https://tinyurl.com/5n6hc4s2.