Interim effects of salt substitution on urinary electrolytes and blood pressure in the China Salt Substitute and Stroke Study (SSaSS).

Sydney School of Public Health, University of Sydney, Sydney, Australia; The George Institute for Global Health, UNSW, Sydney, Australia. The George Institute for Global Health, UNSW, Sydney, Australia; The George Institute for Global Health at Peking University Health Science Centre, Beijing, China. The George Institute for Global Health, UNSW, Sydney, Australia; Department of Cardiology, Peking University Third Hospital, Beijing, China. The George Institute for Global Health, UNSW, Sydney, Australia. The George Institute for Global Health, UNSW, Sydney, Australia; The Friedman School of Nutrition Science and Policy at Tufts University, Boston, United States. The George Institute for Global Health at Peking University Health Science Centre, Beijing, China; Peking University Clinical Research Institute, Beijing, China. School of Public Health, Imperial College London, London, United Kingdom. The George Institute for Global Health at Peking University Health Science Centre, Beijing, China; Duke Global Health Institute, and Global Health Research Centre, Duke Kunshan, University, Kunshan, China. Northwestern University Feinberg School of Medicine, Chicago, United States. The George Institute for Global Health at Peking University Health Science Centre, Beijing, China. First Hospital of China Medical University, Shenyang, China. Changzhi Medical College, Changzhi, China. Center for Disease Control of Hebei, Shijiazhuang, China. Ningxia Medical University, Yinchuan, China. Xi'an Jiaotong University School of Medicine, Xi'an, China. Sydney School of Public Health, University of Sydney, Sydney, Australia; The George Institute for Global Health, UNSW, Sydney, Australia; School of Public Health, Imperial College London, London, United Kingdom. Electronic address: bneal@georgeinstitute.org.au.

American heart journal. 2020;:136-145

Abstract

The Salt Substitute and Stroke Study is an ongoing 5-year large-scale cluster randomized trial investigating the effects of potassium-enriched salt substitute compared to usual salt on the risk of stroke. The study involves 600 villages and 20,996 individuals in rural China. Intermediate risk markers were measured in a random subsample of villages every 12 months over 3 years to track progress against key assumptions underlying study design. Measures of 24-hour urinary sodium, 24-hour urinary potassium, blood pressure and participants' use of salt substitute were recorded, with differences between intervention and control groups estimated using generalized linear mixed models. The primary outcome of annual event rate in the two groups combined was determined by dividing confirmed fatal and non-fatal strokes by total follow-up time in the first 2 years. The mean differences (95% CI) were -0.32 g (-0.68 to 0.05) for 24-hour urinary sodium, +0.77 g (+0.60 to +0.93) for 24-hour urinary potassium, -2.65 mmHg (-4.32 to -0.97) for systolic blood pressure and +0.30 mmHg (-0.72 to +1.32) for diastolic blood pressure. Use of salt substitute was reported by 97.5% in the intervention group versus 4.2% in the control group (P<.0001). The overall estimated annual event rate for fatal and non-fatal stroke was 3.2%. The systolic blood pressure difference and the annual stroke rate were both in line with the statistical assumptions underlying study design. The trial should be well placed to address the primary hypothesis at completion of follow-up.

Methodological quality

Publication Type : Randomized Controlled Trial

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