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Methods of tophus assessment in clinical trials of chronic gout: a systematic literature review and pictorial reference guide
  1. Nicola Dalbeth1,
  2. Cameron Schauer1,
  3. Patricia MacDonald2,
  4. Fernando Perez-Ruiz3,
  5. H Ralph Schumacher4,
  6. Steve Hamburger5,
  7. Hyon K Choi6,
  8. Fiona M McQueen1,
  9. Anthony Doyle1,
  10. William J Taylor7
  1. 1University of Auckland, Auckland, New Zealand
  2. 2Takeda Global Research & Development, Deerfield, Illinois, USA
  3. 3Hospital de Cruces, Rheumatology Section and Nephrology Division, Barakaldo, Pais Vasco, Spain
  4. 4University of Pennsylvania and VA Medical Center, Philadelphia, Pennsylvania, USA
  5. 5Savient Pharmaceuticals, Inc., East Brunswick, New Jersey, USA
  6. 6Boston University School of Medicine, Boston, Massachusetts, USA
  7. 7University of Otago, Wellington, New Zealand
  1. Correspondence to Dr Nicola Dalbeth, Department of Medicine, Faculty of Medical and Health Sciences, University of Auckland, 85 Park Road, Grafton, Auckland, New Zealand; n.dalbeth{at}


Objective To identify methods of tophus measurement for gout studies, summarise the properties of these methods and compile a detailed pictorial reference guide to demonstrate the methods.

Methods A systematic search strategy for methods of tophus measurement was formulated. For each method, papers were assessed by two reviewers to summarise information according to the specific components of the Outcomes Measures in Rheumatology (OMERACT) filter: feasibility, truth and discrimination. Detailed images were obtained to construct the reference guide.

Results Eight methods of tophus measurement were identified: counting the total number of tophi, physical measurement using tape measure, physical measurement using Vernier callipers, digital photography, ultrasonography (US), MRI, CT and dual energy CT. Feasibility aspects of the methods are well documented. Physical measurement techniques are more feasible than advanced imaging methods, but do not allow for assessment of intra-articular tophi or for data storage and central reading. The truth aspect of the filter has been documented for many methods, particularly Vernier callipers, US, MRI and CT. Reliability of most methods has been reported as very good or excellent. Sensitivity to change has been reported for all methods except MRI and CT.

Conclusion A variety of methods of tophus assessment have been described for use in clinical trials of chronic gout. Physical measurement techniques (particularly the Vernier calliper method) and US measurement of tophus size appear to meet most aspects of the OMERACT filter.

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  • Provenance and peer review Not commissioned; externally peer reviewed.