title: Evaluating joint destruction in rheumatoid arthritis: is it necessary to radiograph both hands and feet?
abstract: BACKGROUND
  Radiological damage is an important outcome measure in rheumatoid arthritis (RA), both for research and clinical purposes. Depending on the setting, both hands and feet are radiographed, or only a part of these. It is unknown whether radiographing part of the four extremities gives comparable information to radiographing both hands and feet. This study therefore aimed to compare the radiological information obtained both when evaluating single time point radiographs and progression over time, in early and advanced RA.
  
  
  METHODS
  6261 sets of hands and feet x-rays of 2193 RA patients from Leiden, Groningen (both from The Netherlands) and North America were studied. Correlations between joint damage at different regions were compared (unilateral vs bilateral and hands vs feet). Analyses were done at single time points (cross-sectional) and for progression over time (longitudinal), both for continuous severity measures (Sharp/van der Heijde score; SHS) and binomial measures of erosiveness.
  
  
  RESULTS
  When studying single time points, the severity of joint damage (SHS) is highly correlated between left and right, but weakly correlated between hands and feet. Correlation coefficients were higher in advanced than early RA. These findings were comparable in the three datasets. When evaluating erosiveness using only unilateral x-rays or hands without feet, 19.3% and 24.0-40.4% are incorrectly classified as non-erosiveness. Similarly, when evaluating disease progression by imaging only unilateral x-rays or only hand x-rays, progression would have been missed in 11.6-16.2% and 21.2-31.0% of patients.
  
  
  CONCLUSIONS
  Performing x-rays of both hands and feet yields additive information compared with imaging only a part of these.
authors.affiliation: Department of Rheumatology, Leiden University Medical Center, 2300 RC Leiden, the Netherlands. r.knevel@lumc.nl
authors.forename: R
authors.initials: R
authors.lastname: Knevel
authors.forename: K Y
authors.initials: KY
authors.lastname: Kwok
authors.forename: D P C
authors.initials: DP
authors.lastname: de Rooy
authors.forename: M D
authors.initials: MD
authors.lastname: Posthumus
authors.forename: T W J
authors.initials: TW
authors.lastname: Huizinga
authors.forename: E
authors.initials: E
authors.lastname: Brouwer
authors.forename: A H M
authors.initials: AH
authors.lastname: van der Helm-van Mil
mesh_terms: D001172:Arthritis, Rheumatoid / Q000000981:diagnostic imaging* / Q000473:pathology; D001175:Arthrography; D018450:Disease Progression; D005260:Female; D005528:Foot / Q000000981:diagnostic imaging* / Q000473:pathology; D006225:Hand / Q000000981:diagnostic imaging* / Q000473:pathology; D006801:Humans; D007596:Joints / Q000473:pathology*; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged