Impact of salt substitute and stepwise reduction of salt supply on blood pressure in residents in senior residential facilities: Design and rationale of the DECIDE-Salt trial

Background: High sodium intake has been considered as the leading dietary risk factor for deaths and disability-adjusted life-years among older adults. High-quality randomized trials to evaluate the effects of practical sodium reduction strategies are needed. Methods: The study is a cluster randomized trial with a 2 × 2 factorial design conducted in 48 senior residential facilities in northern China. These facilities are randomly assigned (1:1:1:1) to 1 of 4 groups: stepwise salt supply control (SSSC) in which 5%-10% of the study salt supply in the institutional kitchens will be reduced every 3 months, replacing normal salt with salt substitute (SS); SSSC only; SS only; or neither SSSC nor SS. The interventions last for 2 years with follow-up every 6 months. The primary outcome is the change in systolic blood pressure from baseline to 24 months. Secondary outcomes include the incidence of hyperkalemia, hyponatremia, cardiovascular events, and death. Current status: The study has recruited and randomized 48 senior residential facilities with 1,606 participants. Mean age at baseline was 71 years, and 76% are male. Both types of salt intervention were initiated in the study facilities between January and April 2018. Conclusion: The study is well placed to define the effects of 2 practical and scalable sodium reduction strategies for blood pressure reduction and will provide important new data about safety of these strategies among older adults in China.