title: Implementation of Z-scores as an age- and sex-independent parameter for estimating joint space widths in rheumatoid arthritis.
abstract: OBJECTIVE
  To compare normative data of joint space distances (JSD) with the JSD of patients with rheumatoid arthritis (RA) as measured by computer-aided joint space analysis (CAJSA) at the metacarpophalangeal (MCP) articulations, and to differentiate age- and sex-related alterations from the disease-related joint space narrowing.
  
  
  METHODS
  In total, 256 healthy subjects and 248 patients with verified RA (following revised ACR criteria) underwent computerized semiautomated measurements of JSD (CAJSA, version 1.3.6) at the MCP articulation (JSD-MCP) based on digital radiographs. The Z-score, a comparative parameter that differentiates joint space alterations caused by RA-related cartilage destruction from age- and sex-related changes, was calculated.
  
  
  RESULTS
  Our data showed a relationship between measured joint space widths (MCP total and MCP thumb to little finger) and age for healthy subjects and also the RA group. The RA group revealed an age-related joint space narrowing that was surpassed by the RA-related narrowing of joint space widths classified by Sharp joint space narrowing score and resulting in smaller Z-scores for RA patients.
  
  
  CONCLUSIONS
  The CAJSA technique seems to distinguish age-related JSD changes in healthy volunteers from RA-induced alterations. In addition the Z-score was also able to differentiate RA-dependent narrowing of JSD. Calculation of the Z-scores based on sex- and age-specific reference data may facilitate earlier identification of patients with RA, allowing initiation of a more optimal, individually adapted therapeutic strategy.
authors.affiliation: Institute of Diagnostic and Interventional Radiology, Department of Rheumatilogy and Osteology, Friedrich-Schiller-University Jena, Erlanger Allee 101, 07747 Jena, Germany.
authors.forename: Alexander
authors.initials: A
authors.lastname: Pfeil
authors.forename: Max L
authors.initials: ML
authors.lastname: Schäfer
authors.forename: Gabriele
authors.initials: G
authors.lastname: Lehmann
authors.forename: Bettina E
authors.initials: BE
authors.lastname: Seidl
authors.forename: Thorsten
authors.initials: T
authors.lastname: Eidner
authors.forename: Ansgar
authors.initials: A
authors.lastname: Malich
authors.forename: Diane M
authors.initials: DM
authors.lastname: Renz
authors.forename: Peter
authors.initials: P
authors.lastname: Oelzner
authors.forename: Andreas
authors.initials: A
authors.lastname: Hansch
authors.forename: Gunter
authors.initials: G
authors.lastname: Wolf
authors.forename: Gert
authors.initials: G
authors.lastname: Hein
authors.forename: Werner A
authors.initials: WA
authors.lastname: Kaiser
authors.forename: Joachim
authors.initials: J
authors.lastname: Böttcher
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D001172:Arthritis, Rheumatoid / Q000000981:diagnostic imaging / Q000473:pathology; D005260:Female; D006801:Humans; D008297:Male; D008662:Metacarpophalangeal Joint / Q000000981:diagnostic imaging / Q000473:pathology; D008875:Middle Aged; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D012720:Severity of Illness Index; D012737:Sex Factors; D012984:Software