Reduction of dietary sodium to less than 100 mmol in heart failure (SODIUM-HF): an international, open-label, randomised, controlled trial

Background: Dietary restriction of sodium has been suggested to prevent fluid overload and adverse outcomes for patients with heart failure. We designed the Study of Dietary Intervention under 100 mmol in Heart Failure (SODIUM-HF) to test whether or not a reduction in dietary sodium reduces the incidence of future clinical events.

Methods: SODIUM-HF is an international, open-label, randomised, controlled trial that enrolled patients at 26 sites in six countries (Australia, Canada, Chile, Colombia, Mexico, and New Zealand). Eligible patients were aged 18 years or older, with chronic heart failure (New York Heart Association [NYHA] functional class 2-3), and receiving optimally tolerated guideline-directed medical treatment. Patients were randomly assigned (1:1), using a standard number generator and varying block sizes of two, four, or six, stratified by site, to either usual care according to local guidelines or a low sodium diet of less than 100 mmol (ie, <1500 mg/day). The primary outcome was the composite of cardiovascular-related admission to hospital, cardiovascular-related emergency department visit, or all-cause death within 12 months in the intention-to-treat (ITT) population (ie, all randomly assigned patients). Safety was assessed in the ITT population. This study is registered with ClinicalTrials.gov, NCT02012179, and is closed to accrual.

Findings: Between March 24, 2014, and Dec 9, 2020, 806 patients were randomly assigned to a low sodium diet (n=397) or usual care (n=409). Median age was 67 years (IQR 58-74) and 268 (33%) were women and 538 (66%) were men. Between baseline and 12 months, the median sodium intake decreased from 2286 mg/day (IQR 1653-3005) to 1658 mg/day (1301-2189) in the low sodium group and from 2119 mg/day (1673-2804) to 2073 mg/day (1541-2900) in the usual care group. By 12 months, events comprising the primary outcome had occurred in 60 (15%) of 397 patients in the low sodium diet group and 70 (17%) of 409 in the usual care group (hazard ratio [HR] 0·89 [95% CI 0·63-1·26]; p=0·53). All-cause death occurred in 22 (6%) patients in the low sodium diet group and 17 (4%) in the usual care group (HR 1·38 [0·73-2·60]; p=0·32), cardiovascular-related hospitalisation occurred in 40 (10%) patients in the low sodium diet group and 51 (12%) patients in the usual care group (HR 0·82 [0·54-1·24]; p=0·36), and cardiovascular-related emergency department visits occurred in 17 (4%) patients in the low sodium diet group and 15 (4%) patients in the usual care group (HR 1·21 [0·60-2·41]; p=0·60). No safety events related to the study treatment were reported in either group.

Interpretation: In ambulatory patients with heart failure, a dietary intervention to reduce sodium intake did not reduce clinical events.

Funding: Canadian Institutes of Health Research and the University Hospital Foundation, Edmonton, Alberta, Canada, and Health Research Council of New Zealand.