title: Methods of tophus assessment in clinical trials of chronic gout: a systematic literature review and pictorial reference guide.
abstract: 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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Medicine, Faculty of Medical and Health Sciences, University of Auckland, 85 Park Road, Grafton, Auckland, New Zealand. n.dalbeth@auckland.ac.nz
authors.forename: Nicola
authors.initials: N
authors.lastname: Dalbeth
authors.forename: Cameron
authors.initials: C
authors.lastname: Schauer
authors.forename: Patricia
authors.initials: P
authors.lastname: Macdonald
authors.forename: Fernando
authors.initials: F
authors.lastname: Perez-Ruiz
authors.forename: H Ralph
authors.initials: HR
authors.lastname: Schumacher
authors.forename: Steve
authors.initials: S
authors.lastname: Hamburger
authors.forename: Hyon K
authors.initials: HK
authors.lastname: Choi
authors.forename: Fiona M
authors.initials: FM
authors.lastname: McQueen
authors.forename: Anthony
authors.initials: A
authors.lastname: Doyle
authors.forename: William J
authors.initials: WJ
authors.lastname: Taylor
mesh_terms: D002908:Chronic Disease; D002986:Clinical Trials as Topic; D006073:Gout / Q000175:diagnosis* / Q000188:drug therapy / Q000473:pathology; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D010781:Photography / Q000379:methods; D014057:Tomography, X-Ray Computed / Q000379:methods; D016896:Treatment Outcome