Vitamin D Supplementation in CKD - Vascular Function, Structure and Immune Regulation

Study Overview
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Brief Summary
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A pilot study to assess feasibility of methods of an observer-blinded randomised controlled trial of the effect of vitamin D supplementation in Chronic Kidney Disease and low vitamin D levels on markers of vascular function (Flow Mediated Dilatation of Brachial Artery), vascular structure (Carotid Intima Media Thickness) and Immune Regulation (frequencies of CD4+CD28null T lymphocytes ad Regulatory T lymphocytes).

Detailed Description
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The study is a single (observer) blinded feasibility pilot randomised study. Study subjects will be recruited from clinics run by St George's Hospital Renal Department and randomised to treatment arm or no treatment arm. In treatment arm, six doses of vitamin D tablets (cholecalciferol 100,000 IU, five capsules total) will be administered on weeks 0, 4, 8, 12, 16 and 20. In the no-treatment arm the participants receive no cholecalciferol. Participants will have serum calcium levels measured at week 12. All participants will undergo estimation of endothelial function, carotid intima-media thickness, CD4+CD28null and regulatory T cell frequency in week 0 and week 26. The observer will be blinded to whether the patient is in the treatment or no-treatment arm whilst the following tests are performed: Measurement of Brachial Artery Flow Mediated Dilatation Measurement of Carotid Intima Media Thickness Quantification of CD4+CD28null and regulatory T cell frequency The pilot study will assess feasibility of the study methods.

Official Title
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Impact of Vitamin D Supplementation on Vascular Function, Vascular Structure and Immune Regulation in Patients With Chronic Kidney Disease and Low Vitamin D Levels - A Pilot Randomised Trial

Conditions
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Atherosclerosis, Chronic Kidney Disease

Intervention / Treatment
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* Dietary Supplement: Vitamin D (cholecalciferol)


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Age 18-80 years Calcium < 2.58mmol/l On an ACE inhibitor/ARB Vitamin D <75nmol/l eGFR 15- 60ml/min/1.73m2 and stable Informed consent to participate Exclusion Criteria: Patients already on Vitamin D or calcium supplementation Patients with known malignancies Patients with autoimmune conditions Patients with heart failure (ejection fraction <40%, Plasma NT pro-BNP>500pg/ml) Patients with active infection Rapidly deteriorating renal function Recent Acute coronary syndrome or cerebro-vascular event (within the last 6 months) Uncontrolled hypertension (BP>160 systolic)

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 80 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Other
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Vitamin D Group<br>Six doses of cholecalciferol 100,000units (5x aviticol 20,000units capsules) administered monthly over 20 weeks. | Dietary Supplement: Vitamin D (cholecalciferol)<br>* (aviticol) 5x 20,000unit capsules administered monthly over 20 weeks<br>|
| No Intervention: Control<br>No vitamin D given | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Recruitment rate | Percentage of patients recruited from those eligible for the study. | 3 months | 
| Retention rate | Percentage of patients recruited who completed the follow up investigations | 6 months | 
| Acceptability to patients of randomisation procedures | Acceptability as assessed by quantitative and qualitative analysis of Participant Experience Survey | 6 months | 
| Randomisation procedure | Comparison of baseline indices of two patient groups | 6 months | 
| Maintenance of single (observer) blinding | Incidences of unblinding of study investigator | 6 months | 
| Adherence to vitamin D supplementation | Subjective adherence as assessed by Participant Experience Survey and biochemical correlation by comparison of follow up vitamin D levels | 6 months | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Witnessed change in FMD between treated and untreated subjects | Flow Mediated Dilatation | 6 months | 
| Witnessed change in CIMT between treated and untreated subjects | Carotid Intima Media Thickness | 6 months | 
| Witnessed change in T lymphocyte subset frequency between treated and untreated subjects | CD4+CD28null T lymphocytes and Regulatory T cells as determined by flow cytometry of whole blood | 6 months | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Vitamin D, Cholecalciferol, Chronic Kidney Disease, Cardiovascular Disease, Atherosclerosis, Flow Mediated Dilatation, Carotid Intima Media Thickness, CD4+CD28null T lymphocyte, Regulatory T lymphocyte