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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
Scientific title
Effects of vitamin C on serum urate in patients with gout
Secondary ID [1] 252153 0
N/A
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Gout 257668 0
Condition category
Condition code
Musculoskeletal 257848 257848 0 0
Other muscular and skeletal disorders
Inflammatory and Immune System 257868 257868 0 0
Other inflammatory or immune system disorders

Intervention/exposure
Study type
Interventional
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.
Intervention code [1] 256737 0
Treatment: Other
Intervention code [2] 256738 0
Treatment: Drugs
Comparator / control treatment
Commence or increase dose of allopurinol
Control group
Active

Outcomes
Primary outcome [1] 258712 0
Reduction in serum urate
Timepoint [1] 258712 0
Week 4 and week 8 following randomisation
Secondary outcome [1] 264767 0
Increase in plasma vitamin C and/or plasma oxypurinol
Timepoint [1] 264767 0
Week 4 and week 8 following randomisation

Eligibility
Key inclusion criteria
Gout as defined by American Rheumatology Association (ARA) preliminary classification criteria and a serum urate of >0.36mmol/L
Minimum age
18 Years
Maximum age
No limit
Sex
Both males and females
Can healthy volunteers participate?
No
Key exclusion criteria
Patients taking regular vitamin supplements will be excluded.

Study design
Purpose of the study
Treatment
Allocation to intervention
Randomised controlled trial
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.
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.
Masking / blinding
Open (masking not used)
Who is / are masked / blinded?



Intervention assignment
Parallel
Other design features
Phase
Not Applicable
Type of endpoint/s
Efficacy
Statistical methods / analysis

Recruitment
Recruitment status
Completed
Date of first participant enrolment
Anticipated
2/08/2010
Actual
11/10/2010
Date of last participant enrolment
Anticipated
Actual
7/02/2012
Date of last data collection
Anticipated
Actual
Sample size
Target
40
Accrual to date
Final
40
Recruitment outside Australia
Country [1] 2739 0
New Zealand
State/province [1] 2739 0
Canterbury

Funding & Sponsors
Funding source category [1] 257246 0
Government body
Name [1] 257246 0
Health Research Council of New Zealand
Country [1] 257246 0
New Zealand
Primary sponsor type
Individual
Name
Associate Professor Lisa Stamp
Address
Department of Medicine
University of Otago, Christchurch
P.O. Box 4345
Christchurch 8140
Country
New Zealand
Secondary sponsor category [1] 256496 0
University
Name [1] 256496 0
University of Otago
Address [1] 256496 0
POBox 56
Dunedin 9054
Country [1] 256496 0
New Zealand

Ethics approval
Ethics application status
Approved
Ethics committee name [1] 259245 0
Upper South A Regional Ethics Committee
Ethics committee address [1] 259245 0
c/- Ministry of Health
PO Box 3877
Christchurch 8140
Ethics committee country [1] 259245 0
New Zealand
Date submitted for ethics approval [1] 259245 0
Approval date [1] 259245 0
07/12/2009
Ethics approval number [1] 259245 0
URA/09/11/077

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.
Trial website
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.
Public notes

Contacts
Principal investigator
Name 31351 0
Prof Lisa stamp
Address 31351 0
Dept Medicine POBox 4335 Christchurch New Zealand
Country 31351 0
New Zealand
Phone 31351 0
+6433640953
Fax 31351 0
Email 31351 0
[email protected]
Contact person for public queries
Name 14598 0
Lisa Stamp
Address 14598 0
Department of Medicine
University of Otago, Christchurch
P.O. Box 4345
Christchurch 8140
Country 14598 0
New Zealand
Phone 14598 0
+64 3-364-0953
Fax 14598 0
+64 3 364-0935
Email 14598 0
[email protected]
Contact person for scientific queries
Name 5526 0
Lisa Stamp
Address 5526 0
Department of Medicine
University of Otago, Christchurch
P.O. Box 4345
Christchurch 8140
Country 5526 0
New Zealand
Phone 5526 0
+64 3 364-0953
Fax 5526 0
+64 3 364-0935
Email 5526 0
[email protected]

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