title: Development and testing of reduced joint counts in juvenile idiopathic arthritis.
abstract: OBJECTIVE
  To develop and test reduced joint counts in children with juvenile idiopathic arthritis (JIA).
  
  
  METHODS
  Four reduced joint counts including 45, 35, 27, and 10 joints were devised by a panel of experienced pediatric rheumatologists, who selected the joints to be included based on the ease of technical assessment, functional relevance, and frequency of involvement. Three large samples of patients with JIA (total n=4353) who had a detailed joint assessment available were used to develop and test reduced joint counts. Performance of reduced counts was examined by comparing their Spearman correlation with the standard (i.e., complete) joint count. Construct validity was evaluated by calculating Spearman correlation with other JIA outcome measures. Responsiveness to clinical change was determined through the standardized response mean (SRM).
  
  
  RESULTS
  Spearman correlations of reduced joint counts with the whole joint count and with the other JIA outcome measures were comparable, revealing that they had similar ability to serve as surrogate for the whole joint count and construct validity. Responsiveness to clinical change was also comparable across reduced counts (SRM 0.83-1.09 for active joint counts and 0.63-0.81 for restricted joint counts). Based on these results and considering the relative feasibility of the different counts, the 27-joint reduced count is proposed for use in JIA. This joint count includes the cervical spine and the elbow, wrist, metacarpophalangeal (from first to third), proximal interphalangeal, hip, knee, and ankle joints.
  
  
  CONCLUSIONS
  Reduced joint counts appear to be as reliable as standard joint counts in assessment of the severity of joint disease and its change over time in children with JIA.
authors.affiliation: Istituto di Ricovero e Cura a Carattere Scientifico G. Gaslini, Largo G. Gaslini 5, 16147 Genova, Italy.
authors.forename: Anna
authors.initials: A
authors.lastname: Bazso
authors.forename: Alessandro
authors.initials: A
authors.lastname: Consolaro
authors.forename: Nicolino
authors.initials: N
authors.lastname: Ruperto
authors.forename: Angela
authors.initials: A
authors.lastname: Pistorio
authors.forename: Stefania
authors.initials: S
authors.lastname: Viola
authors.forename: Silvia
authors.initials: S
authors.lastname: Magni-Manzoni
authors.forename: Clara
authors.initials: C
authors.lastname: Malattia
authors.forename: Antonella
authors.initials: A
authors.lastname: Buoncompagni
authors.forename: Anna
authors.initials: A
authors.lastname: Loy
authors.forename: Alberto
authors.initials: A
authors.lastname: Martini
authors.forename: Angelo
authors.initials: A
authors.lastname: Ravelli
mesh_terms: D000293:Adolescent; D001171:Arthritis, Juvenile / Q000473:pathology*; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D016208:Databases, Factual; D006304:Health Status; D006801:Humans; D007596:Joints / Q000473:pathology*; D010808:Physical Examination / Q000592:standards*; D015203:Reproducibility of Results; D012720:Severity of Illness Index