A Randomised Controlled Trial of the Effect of Dietary Salt Reduction on Blood Pressure and Other Cardiovascular Parameters in Kidney Transplant Recipients
Trial Snapshot
- Phase
- Not Applicable
- Enrollment
- 66
- Locations
- 2
- Primary Endpoint
- Office systolic and diastolic BP readings
Study Overview
Brief Summary
Cardiovascular morbidity and mortality is increased in kidney transplant patients. High blood pressure (BP) contributes significantly to this risk and is also associated with shortened allograft survival. Salt reduction lowers BP in the general population and there is emerging data that salt reduction also effectively lowers BP in chronic kidney disease (CKD). Kidney transplant patients, by definition have CKD, but they differ fundamentally from the general CKD population in that they are on medications which can predispose to high blood pressure, their kidneys are denervated, and they often have reasonable excretory kidney function.
The proposed study will be an eight-week randomised, controlled trial assessing the effect of intensive dietary salt advice on cardiovascular risk factors in kidney transplant patients. The primary outcome is office BP readings, with the effect on 24-hour ambulatory blood pressure, proteinuria, arterial stiffness and endothelial function being studied as secondary outcomes.
Detailed Description
Our hypothesis is that lower salt intake will reduce BP in patients with a kidney transplant. We propose that this will translate into better CV and renal protection via reductions in proteinuria, endothelial dysfunction and arterial stiffness.
The primary aim of the study is to examine the impact of reduced dietary salt intake on blood pressure (BP) in kidney transplant patients. Secondary aims include examination of the effect of salt reduction on ambulatory blood pressure parameters, markers of proteinuria, endothelial and metabolic dysfunction, arterial stiffness and renal fibrosis.
The study will be a single centre, randomised controlled parallel study. Individuals aged 18 years old and above will be recruited from the kidney transplant population of the South West Thames Renal Unit. Patients who have received a kidney transplant ≥ 6 months previously who have a BP >130 mm Hg systolic and/or >80 mm Hg diastolic, or are receiving treatment for hypertension will be included.
Informed consent will be obtained from all study participants and each patient will be given a patient information sheet. At the beginning of the 2-week run-in period individuals will be assessed for eligibility with office BP readings and a 24hr urine collection. Baseline measurements will be taken whilst participants are on their usual diet. All measurements will be performed at baseline, after a 2-week run in period, and at the end of the 8-week study period.
After baseline measurements are taken at the end of the 2-week run in period, participants will be randomised to either the low salt arm or the standard treatment arm using computer-generated randomisation. Patients will be asked to bring in a food diary from the weekend and two week days so that dietary advice can be tailored to the individual. Patients allocated to the low salt diet group will be advised by a doctor to achieve a dietary salt intake of less than 5g per day (80mmol/day). The control group will be instructed to continue with their usual diet, therefore no advice will be given about salt reduction, but otherwise the groups will follow an identical trial protocol.
Study Design
- Study Type
- Interventional
- Allocation
- Randomized
- Intervention Model
- Parallel
- Primary Purpose
- Treatment
- Masking
- None
Eligibility Criteria
- Ages
- 18 Years to — (Adult, Older Adult)
- Sex
- All
- Accepts Healthy Volunteers
- No
Inclusion Criteria
- •Patients who have received a kidney transplant ≥ 6 months previously who have a BP >130 mm Hg systolic and/or >80 mm Hg diastolic, or are receiving treatment for hypertension.
Exclusion Criteria
- •BP < 120/80 on blood pressure treatment
- •BP >160/100
- •Variation in Creatinine >20% over preceding 2 months
- •Secondary hypertension due to a cause other than CKD
- •Heart failure (LVEF <30% or NYHA class II - IV)
- •Myocardial Infarction within 6 months
- •Stroke within 6 months
- •Current diagnosis of cancer
- •Liver disease
- •Bilateral arterio-venous fistulae
- •Evidence of significant active infection
- •Females who are pregnant or breastfeeding
- •Hyponatremia (Na <130mmol/L) or Hypernatremia (Na >150mmol/L)
- •Histologically confirmed episode of rejection within 6 months
- •Steroids dose change in preceding 2 months
- •Patients who are not able to give full informed consent
- •Initial 24hr urinary sodium <80mmol/24hrs
Arms & Interventions
Standard Treatment
Patients will be instructed to continue with their usual diet, therefore no advice will be given about salt reduction.
Low Salt Diet
Dietary salt reduction: Patients will be given intensive dietary advice to achieve a low salt diet, targeting a dietary salt intake of less than 5g per day (80 mmol/day).
Intervention: Dietary salt reduction (Other)
Outcomes
Primary Outcomes
Office systolic and diastolic BP readings
Time Frame: 9 months
Systoli and diastolic BP measurements in mmHg
Secondary Outcomes
- Ambulatory BP monitoring(9 months)
- Endothelial function, measured by digital pulse wave analysis (DVP)(9 months)
- Arterial stiffness, measured by digital pulse wave analysis (DVP)(9 months)
- Proteinuria(9 months)
- Biomarkers of fibrosis(9 months)