title: Criteria for generalized and focal osteoarthritis.
abstract: OBJECTIVE
  to identify homogeneous, distinct subgroups of osteoarthritis patients based on distribution of osteoarthritis lesions.
  
  
  METHODS
  
  
  
  METHODS
  cross-sectional, prospective, multicenter. Patients with osteoarthritis of the hip, knee, fingers, or spine.
  
  
  METHODS
  clinical and radiologic features at 41 joint sites.
  
  
  METHODS
  multivariate statistical analysis including a) k-mean clustering analysis followed by ascending hierarchical classification b) and a tree-structured discriminant method to confirm and to characterize the subgroups obtained using the clustering method.
  
  
  RESULTS
  The 1021 patients were first classified into five categories with an error rate (obtained by cross-validation) of 7.6%. The tree obtained by segmentation took into account manifestations of osteoarthritis at the hands, knees and spine. Irrespective of the reason for seeking medical advice, patients with bilateral involvement of the fingers or with involvement of the spine and both femorotibial joints were classified as having generalized osteoarthritis; in contrast, focal osteoarthritis was defined as the absence of involvement of the fingers and of either the spine or the knees.
  
  
  CONCLUSIONS
  The statistical analysis provided a classification system that would be easy to use in everyday clinical practice. Prospective studies are needed to evaluate the potential clinical relevance of this system.
authors.affiliation: Department of Rheumatology, Cochin Hospital, René-Descartes University, Paris, France.
authors.forename: M
authors.initials: M
authors.lastname: Dougados
authors.forename: J P
authors.initials: JP
authors.lastname: Nakache
authors.forename: A
authors.initials: A
authors.lastname: Gueguen
mesh_terms: D016000:Cluster Analysis; D003430:Cross-Sectional Studies; D016002:Discriminant Analysis; D005384:Finger Joint; D006215:Hallux Valgus / Q000145:classification; D006621:Hip Joint; D006801:Humans; D007719:Knee Joint; D015999:Multivariate Analysis; D010003:Osteoarthritis / Q000145:classification*; D011446:Prospective Studies; D013131:Spine; D014033:Toe Joint