Rationale and design of the Sodium Lowering In Dialysate (SoLID) trial: a randomised controlled trial of low versus standard dialysate sodium concentration during hemodialysis for regression of left ventricular mass

Abstract

BackgroundThe current literature recognises that left ventricular hypertrophy makes a key contribution to the high rate of premature cardiovascular mortality in dialysis patients. Determining how we might intervene to ameliorate left ventricular hypertrophy in dialysis populations has become a research priority. Reducing sodium exposure through lower dialysate sodium may be a promising intervention in this regard. However there is clinical equipoise around this intervention because the benefit has not yet been demonstrated in a robust prospective clinical trial, and several observational studies have suggested sodium lowering interventions may be deleterious in some dialysis patients.Methods/designThe Sodium Lowering in Dialysate (SoLID) study is funded by the Health Research Council of New Zealand. It is a multi-centre, prospective, randomised, single-blind (outcomes assessor), controlled parallel assignment 3-year clinical trial. The SoLID study is designed to study what impact low dialysate sodium has upon cardiovascular risk in dialysis patients. The study intends to enrol 118 home hemodialysis patients from 6 sites in New Zealand over 24 months and follow up each participant over 12 months. Key exclusion criteria are: patients who dialyse more frequently than 3.5 times per week, pre-dialysis serum sodium of <135 mM, and maintenance hemodiafiltration. In addition, some medical conditions, treatments or participation in other dialysis trials, which contraindicate the SoLID study intervention or confound its effects, will be exclusion criteria. The intervention and control groups will be dialysed using dialysate sodium 135 mM and 140 mM respectively, for 12 months. The primary outcome measure is left ventricular mass index, as measured by cardiac magnetic resonance imaging, after 12 months of intervention. Eleven or more secondary outcomes will be studied in an attempt to better understand the physiologic and clinical mechanisms by which lower dialysate sodium alters the primary end point.DiscussionThe SoLID study is designed to clarify the effect of low dialysate sodium upon the cardiovascular outcomes of dialysis patients. The study results will provide much needed information about the efficacy of a cost effective, economically sustainable solution to a condition which is curtailing the lives of so many dialysis patients.Trial registrationAustralian and New Zealand Clinical Trials Registry number: ACTRN12611000975998

Hemodialysis‐induced regional left ventricular systolic dysfunction

“…We look forward to the information and results brought by this trial. 52 HD-induced myocardial dysfunction is common in HD patients, especially in those with higher hs-cTnT, serum phosphate, and UFR, and lower albumin level patients. Transient myocardial ischemia caused by HD can lead to temporary LV dysfunction and stunning, and repeat episodes of stunning may lead to structural and functional abnormalities, and eventually heart failure.…”

“…Beyond these strategies, the Sodium Lowering in Dialysate (SoLID) trial is a multicenter, randomized, controlled 3‐year trial in New Zealand, which is still keep going to clarify the effect of dialysate sodium concentration on the cardiovascular risks among HD patients. We look forward to the information and results brought by this trial …”

Rationale and design of the myocardial microinjury and cardiac remodeling extension study in the sodium lowering in dialysate trial (Mac-SoLID study)

“…The proposed research will be conducted as an extension of the ongoing SoLID trial, a multi-center prospective, randomized, single-blind (outcomes assessor), active controlled, parallel assignment 3-year clinical trial [1,2]. …”

“…The rationale and protocol for the SoLID trial have been previously published [1,2]. There will be accrual of participants over 24 months, and a follow-up duration of 12 months.…”

Why does the choice of dialysate sodium concentration remain controversial?

“…Although choosing a higher dialysate sodium (≥ 140 mEq/L) concentration was associated with increased IDWG, a recent systematic review of 23 studies, was unable to demonstrate any convincing overall superiority for the use of either a lower or higher dialysate sodium concentration on adverse intradialytic events, BP control, hospitalization, or patient mortality . Currently, there is one multicenter randomized controlled trial (sodium lowering in dialysate trial) recruiting patients to determine effect of dialysate sodium exposure on left ventricular mass …”