Effectiveness of an mHealth and school-based health education programme for salt reduction (EduSaltS) in China: cluster randomized controlled trial within scale-up.

Abstract

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

Objective: This study aims to evaluate the effectiveness of the real-world implementation of an mHealth and school-based health education scale-up programme to reduce salt (EduSaltS).

Methods: A parallel, cluster randomized controlled trial was conducted from April 2022 to July 2023 across 20 schools in two districts and two counties within Ganzhou City, Jiangxi Province, China. Schools were randomly assigned in a 1:1 ratio to either intervention or control group within each district or county. One third-grade class per school and twenty-six students from each class were selected using simple random sampling. Subsequently, one parent of each participating student was invited to join. If a parent was unavailable, an alternative family member aged 18-75 years and residing with the student was recruited. The EduSaltS intervention, which spanned over one academic year, incorporated both online health education courses and offline salt reduction activities, with participation being monitored through the backend management system. The effectiveness of the intervention was assessed by comparing changes in salt intake and blood pressure between the intervention and control groups from baseline to one-year follow-up, using data from surveys, physical examination, and 24-hour urine laboratory tests.

Results: Of the 524 children (288 (54.96%) boys; mean age 9.16 (SD=0.35) years) and 524 adults (194 (37.02%) men; mean age 40.99 (SD=11.04) years) who participated and completed the baseline assessments in 10 intervention and 10 control schools, the loss to follow-up rate was 2.48% (13/524) for children and 8.97% (47/524) for adults. All schools and participants showed satisfactory adherence to the intervention. For schoolchildren, the measured difference in salt intake, SBP and DBP, between the intervention and the control schools, was -0.24g/day (95%CI:-0.77 to 0.65), -0.66mmHg (95%CI:-2.35 to 1.04), and -1.37mmHg (95%CI:-2.79 to 0.06) respectively. For adults, salt intake in the intervention group decreased from 9.0 (SE=0.2) g/day to 8.3 (SE=0.2) g/day after intervention. Compared with the control group, the adjusted change in the intervention group for salt intake, SBP, and DBP were -1.06g/day (95%CI:-1.81 to -0.30), -2.26mmHg (95%CI:-4.26 to -0.26), and -2.33mmHg (95%CI:-3.84 to -0.82), respectively.

Conclusions: The EduSaltS comprehensive intervention programme, delivered through primary schools with a child-to-parent approach, was effective in reducing salt intake and blood pressure control 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.

Clinicaltrial: Chinese Clinical Trial Registry ChiCTR2400079893, retrospectively registered on January 15, 2024 (embedded in an prospectively registered scale-up study, ChiCTR2000039767), https://www.chictr.org.cn/showproj.html?proj=199678.