title: Intra- and interobserver reliability of the Eaton classification for trapeziometacarpal arthritis: a systematic review.
abstract: BACKGROUND
  Trapeziometacarpal, or thumb carpometacarpal (CMC), arthritis is a common problem with a variety of treatment options. Although widely used, the Eaton radiographic staging system for CMC arthritis is of questionable clinical utility, as disease severity does not predictably correlate with symptoms or treatment recommendations. A possible reason for this is that the classification itself may not be reliable, but the literature on this has not, to our knowledge, been systematically reviewed.
  
  
  OBJECTIVE
  We therefore performed a systematic review to determine the intra- and interobserver reliability of the Eaton staging system.
  
  
  METHODS
  We systematically reviewed English-language studies published between 1973 and 2013 to assess the degree of intra- and interobserver reliability of the Eaton classification for determining the stage of trapeziometacarpal joint arthritis and pantrapezial arthritis based on plain radiographic imaging. Search engines included: PubMed, Scopus(®), and CINAHL. Four studies, which included a total of 163 patients, met our inclusion criteria and were evaluated. The level of evidence of the studies included in this analysis was determined using the Oxford Centre for Evidence Based Medicine Levels of Evidence Classification by two independent observers.
  
  
  RESULTS
  A limited number of studies have been performed to assess intra- and interobserver reliability of the Eaton classification system. The four studies included were determined to be Level 3b. These studies collectively indicate that the Eaton classification demonstrates poor to fair interobserver reliability (kappa values: 0.11-0.56) and fair to moderate intraobserver reliability (kappa values: 0.54-0.657).
  
  
  CONCLUSIONS
  Review of the literature demonstrates that radiographs assist in the assessment of CMC joint disease, but there is not a reliable system for classification of disease severity. Currently, diagnosis and treatment of thumb CMC arthritis are based on the surgeon's qualitative assessment combining history, physical examination, and radiographic evaluation. Inconsistent agreement using the current common radiographic classification system suggests a need for better radiographic tools to quantify disease severity.
authors.affiliation: Division of Plastic and Reconstructive Surgery, Stanford University Medical Center, Palo Alto, CA, USA, ab.mdphd@gmail.com.
authors.forename: Aaron J
authors.initials: AJ
authors.lastname: Berger
authors.forename: Arash
authors.initials: A
authors.lastname: Momeni
authors.forename: Amy L
authors.initials: AL
authors.lastname: Ladd
mesh_terms: D001168:Arthritis / Q000000981:diagnostic imaging*; D052737:Carpometacarpal Joints / Q000000981:diagnostic imaging*; D006801:Humans; D015588:Observer Variation; D011237:Predictive Value of Tests; D011379:Prognosis; D011859:Radiography; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D013933:Thumb / Q000000981:diagnostic imaging*
references.citation: Scand J Rheumatol. 1999;28(5):305-7
references.pmid: 10568427
references.citation: Cochrane Database Syst Rev. 2009 Oct 07;(4):CD004631
references.pmid: 19821330
references.citation: J Hand Surg Am. 2002 Sep;27(5):882-5
references.pmid: 12239680
references.citation: J Hand Surg Am. 2011 Sep;36(9):1467-70
references.pmid: 21802867
references.citation: Am J Phys Med Rehabil. 2007 Jan;86(1):12-21
references.pmid: 17304684
references.citation: J Hand Surg Eur Vol. 2013 Feb;38(2):187-91
references.pmid: 22490999
references.citation: J Bone Joint Surg Am. 2005 Dec;87(12):2614-2618
references.pmid: 16322609
references.citation: J Hand Surg Br. 1994 Jun;19(3):340-1
references.pmid: 8077824
references.citation: Hand Clin. 1987 Nov;3(4):455-71
references.pmid: 3693416
references.citation: J Hand Surg Eur Vol. 2013 Oct;38(8):851-9
references.pmid: 23134777
references.citation: J Bone Joint Surg Am. 1973 Dec;55(8):1655-66
references.pmid: 4804988
references.citation: Orthop Clin North Am. 1973 Apr;4(2):331-8
references.pmid: 4707436
references.citation: J Hand Surg Am. 2009 Oct;34(8):1402-6
references.pmid: 19744803
references.citation: J Hand Surg Am. 2007 Apr;32(4):459-65
references.pmid: 17398355
references.citation: J Bone Joint Surg Am. 2004 Jul;86(7):1452-7
references.pmid: 15252092
references.citation: J Hand Surg Br. 2004 Apr;29(2):173-7
references.pmid: 15010167