Process evaluation of an mHealth-based school education program to reduce salt intake scaling up in China (EduSaltS): a mixed methods study using the RE-AIM framework.

Background: An mHealth-based school health education platform (EduSaltS) was promoted in real-world China to reduce salt intake among children and their families. This progress evaluation explores its implementation process and influencing factors using mixed methods.

Methods: The mixed-methods process evaluation employed the RE-AIM framework. Quantitative data were collected from a management website monitoring 54,435 third-grade students across two cities. Questionnaire surveys (n = 27,542) assessed pre- and post-education effectiveness. Mixed-effects models were used to control cluster effects. Qualitative interviews (23 individuals and 8 focus groups) identified program performance, facilitators, and barriers. Findings were triangulated using the RE-AIM framework.

Results: The program achieved 100% participation among all the third-grade classes of the 208 invited primary schools, with a 97.7% registration rate among all the 54,435 families, indicating high "Reach." Qualitative interviews revealed positive engagement from children and parents through the "small hands leading big hands" strategy. The high completion rate of 84.9% for each health cloud lesson and the significant improvement in salt reduction knowledge and behaviors scores from 75.0 (95%CI: 74.7-75.3) to 80.9 (95%CI: 80.6-81.2) out of 100 demonstrated the "Effect" of EduSaltS. The program's "Adoption" and "Implementation" were supported by attractive materials, reduced workload via auto-delivered lessons/activities and performance evaluation, and high fidelity to recommended activities, with medians 3.0 (IQR: 2.0-8.0)/class and 9.0 (IQR: 5.0-14.0)/school. Stable course completion rates (79.4%-93.4%) over one year indicated promising "Maintenance." Apart from the facilitating features praised by the interviewees, government support was the basis for the scaling up of EduSaltS. Barriers included the lack of smartphone skills among some parents and competing priorities for schools. Unhealthy off-campus environments, such as excessive use of salt in pre-packaged and restaurant foods, also hindered salt reduction efforts. The program's scalability was evident through its integration into existing health education, engagement of local governments and adaptation across various mobile devices.

Conclusions: The mHealth-based school health education program is scalable and effective for public salt reduction in China. Identified barriers and facilitators can inform future health program scale-ups. The program's successful implementation demonstrates its potential for broader application in public health initiatives aimed at reducing dietary salt intake.