Validation Study of Physical Measurement of Tophi

Study Overview
=================
Brief Summary
-----------------
The purpose of this study is to determine the inter- and intra-rater reproducibility of direct physical measurement of tophus nodules in subjects with gout.

Detailed Description
-----------------
Gout is a chronic urate crystal deposition disorder. Left untreated, gout may result in progressive disease characterized by joint and bone destruction from tophaceous deposits and renal impairment due to gouty nephropathy. Hyperuricemia, defined as a serum urate concentration greater than 7.0 milligrams per deciliter (mg/dL), is the underlying metabolic aberration leading to urate crystal deposition in gout. Gout has several clinical presentations, including: recurrent acute attacks of inflammatory arthritis; deposition of monosodium urate monohydrate crystals in joints, bones and even parenchymal organs (tophaceous gout); renal impairment; and uric acid nephrolithiasis.1 As serum urate levels increase beyond greater than 7.0 mg/dL, the risks for gouty arthritis or for renal calculi increase. Febuxostat is a 2-aryl-thiazole derivative chemically engineered as a novel xanthine oxidase/dehydrogenase inhibitor. Febuxostat is being developed as an orally administered agent for the management of hyperuricemia in patients with gout. Subjects with palpable tophi >10 millimeters (mm) in length and width and as round as possible will have the tophus measured on two separate visits by two different raters to assess the inter- and intra-rater reproducibility of direct physical measurement.

Official Title
-----------------
A Study to Assess a Direct Physical Measurement Method for Evaluation of Tophus Nodules in Subjects With Gout.

Conditions
-----------------
Gout

Intervention / Treatment
-----------------
* Other: Measurement of Tophi to validate procedure


Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion Criteria: Must have at least 1 palpable gouty tophus nodule in the foot/ankle, hand/wrist, or elbow, confirmed as gouty by prior diagnosis according to ACR criteria. The tophus must be solid, round, non-tender, intact, and larger than 10mm in both length and width. Joints nearest and immediately adjacent to the selected tophus must not be acutely inflamed. Must be on stable treatment for gout with no medication changes in the past 30 days. Exclusion Criteria: Must be able to return to the clinical site within 10 days. Must not have allergy to ink.

Ages Eligible for Study
-----------------
Minimum Age: 18 Years
Maximum Age: 85 Years

Sexes Eligible for Study
-----------------
All

Accepts Healthy Volunteers
-----------------
No

Study Plan
=================
How is the study designed?
-----------------

Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Tophi Participants<br> | Other: Measurement of Tophi to validate procedure<br>* Intra- and Inter-rater Reproducibility measurements of the area (in mm2) of each tophus nodule.<br>|

What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Average Percent Difference in Area Between Visits | The rater measured length and width (mm) of the tophus at 2 visits separated by no more than 10 days. Area of the tophus was summarized using average percent difference, calculated as absolute difference of Visits 1 and 2 divided by the average of Visits 1 and 2 for the same tophus, pooled across raters. | Visit 1 (Day 1) and Visit 2 (Days 6-11) | 
| Average Percent Difference in Area Between Raters | Each rater measured length and width (mm) of the tophus at 2 visits separated by no more than 10 days. Area of the tophus was summarized using the average percent difference, calculated as the absolute difference of Raters 1 and 2 divided by the average of Raters 1 and 2 for the same tophus, pooled across visits. | Visit 1 (Day 1 ) and Visit 2 (Day 6-11) | 

 Terms related to the study
=================
Keywords Provided by Centre Hospitalier Valida
-----------------
Hyperuricemia, Tophi, Tophus, Drug Therapy