China Salt Substitute and Stroke Study (SSaSS)

Lowering salt intake or using salt substitute have been proved to lower blood pressure levels, however, whether they will reduce the risks of vascular outcomes remains uncertain. Rural Chinese are known to consume very large quantities of sodium and to suffer from very high rates of hypertension and stroke.

This study is a large scale cluster randomised trial conducted in rural area in China, aiming to evaluate the effects of replacing usual salt with a low sodium salt substitute on the incidence of stroke and mortality. The primary endpoint will be stroke; secondary endpoints will include major cardiovascular events and total mortality.

The study will be conducted in 600 rural villages across five Northern provinces and Tibet. The study will recruit 35 high risk individuals from each village, making a total of 21,000 participants. The participating villages will be randomised into intervention and control group with 1:1 allocation. Recruitment will prioritise individuals with a prior history of stroke and when the recruitment target is not met, individuals that are aged 60 years or older with uncontrolled hypertension will be recruited.

The study follow up will last for five years. Individuals recruited from intervention villages will receive free supply of low sodium salt substitute to replace their use of usual salt and education about the benefits of salt reduction, while individuals recruited from control villages will continue with their usual diet and receive some advice to reduce their salt intake at baseline only.

Every six months throughout follow-up the team will contact each individual by phone call to inquire about the occurrence of stroke, hospitalisations for other causes and diagnoses of serious illnesses. For all deaths identified and all events that are suspected to be non-fatal strokes a home visit will be made.

The process indicators including urinary sodium, urinary potassium, blood pressure, knowledge about sodium and use of salt substitute will be measured on a random sample of at least 20 individuals drawn from a stratified random sample of 60 villages at baseline and every year thereafter.