ANZCTR - Registration

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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]

N/A

Universal Trial Number (UTN)

Trial acronym

Linked study record

Health condition

Health condition(s) or problem(s) studied:

Gout

Condition category

Condition code

Musculoskeletal

Other muscular and skeletal disorders

Inflammatory and Immune System

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]

Treatment: Other

Intervention code [2]

Treatment: Drugs

Comparator / control treatment

Commence or increase dose of allopurinol

Control group

Active

Outcomes

Primary outcome [1]

Reduction in serum urate

Timepoint [1]

Week 4 and week 8 following randomisation

Secondary outcome [1]

Increase in plasma vitamin C and/or plasma oxypurinol

Timepoint [1]

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?

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

Accrual to date

Final

Recruitment outside Australia

Country [1]

New Zealand

State/province [1]

Canterbury

Funding & Sponsors

Funding source category [1]

Government body

Name [1]

Health Research Council of New Zealand

Address [1]

P.O Box 5541,
Wellesley Street
Auckland 1141

Country [1]

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]

University

Name [1]

University of Otago

Address [1]

POBox 56
Dunedin 9054

Country [1]

New Zealand

Ethics approval

Ethics application status

Approved

Ethics committee name [1]

Upper South A Regional Ethics Committee

Ethics committee address [1]

c/- Ministry of Health
PO Box 3877
Christchurch 8140

Ethics committee country [1]

New Zealand

Date submitted for ethics approval [1]

Approval date [1]

07/12/2009

Ethics approval number [1]

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

Prof Lisa stamp

Address

Dept Medicine POBox 4335 Christchurch New Zealand

Country

New Zealand

Phone

+6433640953

Fax

lisa.stamp@cdhb.govt.nz

Contact person for public queries

Name

Lisa Stamp

Address

Department of Medicine
University of Otago, Christchurch
P.O. Box 4345
Christchurch 8140

Country

New Zealand

Phone

+64 3-364-0953

Fax

+64 3 364-0935

lisa.stamp@cdhb.govt.nz

Contact person for scientific queries

Name

Lisa Stamp

Address

Department of Medicine
University of Otago, Christchurch
P.O. Box 4345
Christchurch 8140

Country

New Zealand

Phone

+64 3 364-0953

Fax

+64 3 364-0935

lisa.stamp@cdhb.govt.nz

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

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Documents added automatically

No additional documents have been identified.

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