Process evaluation of Samoa's national salt reduction strategy (MASIMA): what interventions can be successfully replicated in lower-income countries?

Background: Evidence for recommended interventions to reduce population salt intake come from high-income countries, but it is unknown if these can be successfully replicated in low- and middle-income countries. This process evaluation investigated the reach, dose/adoption, fidelity, cost, and context of a national salt reduction program of interventions in Samoa.

Methods: Monitoring and Action on Salt in Samoa (MASIMA) was a pre- and post-intervention study of a government-led strategy to lower population salt intake comprising awareness campaigns, community mobilization and policy and environmental changes. Data relating to the five process evaluation dimensions were collected from routinely collected data, a post-intervention survey and stakeholder interviews. Chi-squared tests assessed differences in quantitative survey responses among groups. Thematic analysis of qualitative interview responses was undertaken and triangulated with the quantitative data.

Results: Awareness campaigns, school nutrition standards, and community mobilization interventions were implemented with moderate reach and fidelity. Higher than expected costs of campaigns and limited opportunity (one-off) to mobilize community leaders to disseminate salt reduction messages were key implementation challenges, which meant intervention dose was low. Environmental-level initiatives including engagement with the food industry to voluntary reduce salt in foods and the introduction of salt-related regulations were more challenging to implement within 18-months, particularly given the delay in the passing of the Food Act which provides for enforcement of regulations. Contextual factors that hindered the interventions' mechanism of effect include the food culture, higher cost, and lower availability of healthy low-salt foods relative to unhealthy foods and salty taste preference.

Conclusion: Although individual and community-based interventions helped increase awareness about the importance of salt reduction in Samoa, legislative backing was needed to alter the food environment to achieve population reduction in salt intake. It was not possible to engage the food industry to lower salt in foods through a voluntary approach in Samoa's current context, although such initiatives were successful in some high-income countries. Future individual and environmental-level interventions to reduce salt intake need to address the contextual influences of food choices. In Samoa, this means salt reduction strategies need to ensure consuming lower salt is affordable, widely available, and perceived as flavorsome.