Abstract
Despite the recognition that tophus regression is an important outcome measure in clinical trials of chronic gout, there is no agreed upon method of tophus measurement. A number of methods have been used in clinical trials of chronic gout, from simple physical measurement techniques to more complex advanced imaging methods. This article summarizes methods of tophus measurement and discusses their properties. Physical measurement using Vernier calipers meets most aspects of the Outcome Measures in Rheumatology (OMERACT) filter. Rigorous testing of the complex methods, particularly with respect to reliability and sensitivity to change, is needed to determine the appropriate use of these methods. Further information is also required regarding which method of physical measurement is best for use in future clinical trials. The need to develop and test a patient-reported outcome measure of tophus burden is also highlighted.
Footnotes
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Supported by resources and use of facilities at the Birmingham VA Medical Center, Alabama, USA (Dr. Singh). Dr. Khanna is the recipient of an American College of Rheumatology REF Clinical Investigator Award (Quality of Life and Healthcare Utilization in Chronic Gout). Dr. Neogi is supported by NIAMS 5K23AR55127. Dr. Dalbeth has received consultant fees from Takeda and Novartis. Dr. Singh has received speaker honoraria from Abbott; research and travel grants from Allergan, Takeda, Savient, Wyeth, and Amgen; and consultant fees from Savient, URL Pharmaceuticals, and Novartis. Dr. Simon has served on the Board of Directors for Savient Pharmaceuticals and as a consultant for Takeda. Ms MacDonald is an employee of Takeda. Dr. Becker has received consultant fees from Takeda, Savient, BioCryst, URL Pharmaceuticals, Ardea, and Regeneron.