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Trial registered on ANZCTR
Registration number
ACTRN12610000545066
Ethics application status
Approved
Date submitted
6/07/2010
Date registered
7/07/2010
Date last updated
16/09/2016
Type of registration
Prospectively registered
Titles & IDs
Public title
Vitamin C and gout
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Scientific title
Effects of vitamin C on serum urate in patients with gout
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Secondary ID [1]
252153
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N/A
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Universal Trial Number (UTN)
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Trial acronym
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Linked study record
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Health condition
Health condition(s) or problem(s) studied:
Gout
257668
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Condition category
Condition code
Musculoskeletal
257848
257848
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0
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Other muscular and skeletal disorders
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Inflammatory and Immune System
257868
257868
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0
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Other inflammatory or immune system disorders
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Intervention/exposure
Study type
Interventional
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Description of intervention(s) / exposure
Forty patients with gout and persistent hyperuricaemia (serum urate >0.36mmol/L) will be recruited. Patients not already receiving allopurinol will commence either oral vitamin C 500mg/d or oral allopurinol. The dose of allopurinol will be determined by the treating physician based on renal function to achieve a target serum urate of <0.36mmol/L. It is anticipated that the dose of allopurinol will be between 100 and 600mg/day. Patients already receiving allopurinol will have the dose of allopurinol increased (by 50-100mg/day) as determined by the physician based on renal function or commence oral vitamin C 500mg/d. The overall duration of the vitamin C intervention will be 8 weeks. Allopurinol will be continued as it remains the standard treatment for gout after the 8 week period.
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Intervention code [1]
256737
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Treatment: Other
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Intervention code [2]
256738
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Treatment: Drugs
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Comparator / control treatment
Commence or increase dose of allopurinol
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Control group
Active
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Outcomes
Primary outcome [1]
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Reduction in serum urate
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Assessment method [1]
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Timepoint [1]
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Week 4 and week 8 following randomisation
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Secondary outcome [1]
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Increase in plasma vitamin C and/or plasma oxypurinol
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Assessment method [1]
264767
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Timepoint [1]
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Week 4 and week 8 following randomisation
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Eligibility
Key inclusion criteria
Gout as defined by American Rheumatology Association (ARA) preliminary classification criteria and a serum urate of >0.36mmol/L
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Minimum age
18
Years
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Maximum age
No limit
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Sex
Both males and females
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Can healthy volunteers participate?
No
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Key exclusion criteria
Patients taking regular vitamin supplements will be excluded.
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Study design
Purpose of the study
Treatment
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Allocation to intervention
Randomised controlled trial
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Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
20 patients will already be receiving allopurinol at the recommended dose but with a suboptimal effect as determined by serum urate >0.36mmol/L. Patients will be randomised on a one–one ratio to either increase the dose of allopurinol or add vitamin C 500mg/d.
20 patients will require commencement of urate lowering therapy. Patients will be randomised on a one–one ratio to either commence allopurinol or commence vitamin C 500mg/d. Allocation is not concealed.
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Methods used to generate the sequence in which subjects will be randomised (sequence generation)
The randomisation sequence was computer generated in permuted blocks with stratification based on current treatment with allopurinol or not, by the independent study statistician.
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Masking / blinding
Open (masking not used)
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Who is / are masked / blinded?
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Intervention assignment
Parallel
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Other design features
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Phase
Not Applicable
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Type of endpoint/s
Efficacy
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Statistical methods / analysis
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Recruitment
Recruitment status
Completed
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Date of first participant enrolment
Anticipated
2/08/2010
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Actual
11/10/2010
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Date of last participant enrolment
Anticipated
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Actual
7/02/2012
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Date of last data collection
Anticipated
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Actual
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Sample size
Target
40
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Accrual to date
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Final
40
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Recruitment outside Australia
Country [1]
2739
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New Zealand
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State/province [1]
2739
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Canterbury
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Funding & Sponsors
Funding source category [1]
257246
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Government body
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Name [1]
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Health Research Council of New Zealand
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Address [1]
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P.O Box 5541,
Wellesley Street
Auckland 1141
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Country [1]
257246
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New Zealand
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Primary sponsor type
Individual
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Name
Associate Professor Lisa Stamp
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Address
Department of Medicine
University of Otago, Christchurch
P.O. Box 4345
Christchurch 8140
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Country
New Zealand
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Secondary sponsor category [1]
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University
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Name [1]
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University of Otago
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Address [1]
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POBox 56
Dunedin 9054
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Country [1]
256496
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New Zealand
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Ethics approval
Ethics application status
Approved
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Ethics committee name [1]
259245
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Upper South A Regional Ethics Committee
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Ethics committee address [1]
259245
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c/- Ministry of Health PO Box 3877 Christchurch 8140
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Ethics committee country [1]
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New Zealand
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Date submitted for ethics approval [1]
259245
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Approval date [1]
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07/12/2009
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Ethics approval number [1]
259245
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URA/09/11/077
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Summary
Brief summary
Objective: Studies in human volunteers have shown that vitamin C reduces serum urate (SU). The aim of this study was to determine effects of vitamin C on SU in patients with gout. Methods: Patients with gout and SU >0.36mmol/L (6mg/dl) were recruited. 20 patients already receiving allopurinol were randomised to an increase in allopurinol dose or commenced on vitamin C 500mg/d. 20 patients not receiving allopurinol were randomised to start allopurinol or vitamin C 500mg/d. Plasma ascorbate, creatinine, and SU were measured at day 0 and week 8. Results: There was no significant difference in baseline SU or eGFR between those who received vitamin C and those who did not (SU 0.50+/-0.11mmol/l (8.4 +/- 1.8mg/dl) vs. 0.50+/-0.09mmol/l (8.4 +/-1.5mg/dl) p=0.89; eGFR 65.5+/-15.7ml/min/1.73m2 vs. 67.9+/-20.7 ml/min/1.73m2 p=0.67). 30% in the vitamin C group and 25% in the no vitamin C group were receiving diuretics (p=0.72). In the patients receiving vitamin C there was a significant increase between week 0 and 8 in plasma ascorbate. The reduction in SU was significantly less in those patients receiving vitamin C compared to those who started or increased the dose of allopurinol (0.014mmol/l (0.23mg/dl) vs. 0.118 (1.9mg/dl) mmol/l p<0.001). Conclusion: Modest dose vitamin C (500mg/d) for 8 weeks had no clinically significant urate lowering effect in patients with gout despite increasing plasma ascorbate. These results differ from findings in hyperuricaemic healthy controls. The uricosuric effect of modest dose vitamin C appears less in patients with gout both as monotherapy and in combination with allopurinol.
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Trial website
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Trial related presentations / publications
Seis CW, Florkowski CM, Frampton CMA, O’Donnell JL, Chapman PC and Stamp LK. Comparison of two plasma urate assays in patients receiving Vitamin C supplementation. Pathology 2014 (In press). Stamp LK, O’Donnell JL, Frampton C, Drake J, Zhang M and Chapman PT. Clinically insignificant effect of supplemental vitamin C on serum urate in patients with gout; a pilot randomised controlled trial. Arthritis Rheum 2013;65:1636-42.
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Public notes
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Contacts
Principal investigator
Name
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Prof Lisa stamp
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Address
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Dept Medicine POBox 4335 Christchurch New Zealand
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Country
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New Zealand
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Phone
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+6433640953
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Fax
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Email
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[email protected]
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Contact person for public queries
Name
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Lisa Stamp
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Address
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Department of Medicine
University of Otago, Christchurch
P.O. Box 4345
Christchurch 8140
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Country
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New Zealand
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Phone
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+64 3-364-0953
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Fax
14598
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+64 3 364-0935
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Email
14598
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[email protected]
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Contact person for scientific queries
Name
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Lisa Stamp
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Address
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Department of Medicine
University of Otago, Christchurch
P.O. Box 4345
Christchurch 8140
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Country
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New Zealand
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Phone
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+64 3 364-0953
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Fax
5526
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+64 3 364-0935
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Email
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[email protected]
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No information has been provided regarding IPD availability
What supporting documents are/will be available?
No Supporting Document Provided
Results publications and other study-related documents
Documents added manually
No documents have been uploaded by study researchers.
Documents added automatically
No additional documents have been identified.
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