title: OMERACT/OARSI initiative to define states of severity and indication for joint replacement in hip and knee osteoarthritis.
abstract: OBJECTIVE
  Time to theoretical indication of joint replacement surgery has been proposed as a primary outcome for potential structure-modifying interventions for osteoarthritis (OA). The objectives of this OMERACT/OARSI Working Group were to identify pain, physical function, and structure states that represent the progression from early to late disease for individuals with OA of the hip and knee, and to create a composite measure of these 3 domains to define states of OA severity and a surrogate measure of "need for joint replacement surgery."
  
  
  METHODS
  For pain, focus groups and one-on-one interviews were used. For function, Rasch analysis was performed on existing indices the Hip Dysfunction and Osteoarthritis Outcome Score (HOOS) and the Knee injury and Osteoarthritis Outcome Score (KOOS), each of which subsumes the Western Ontario and McMaster University Osteoarthritis Index (WOMAC) questions. For structure, a comparison of existing indices (Kellgren-Lawrence, OARSI stages, and joint space width) was performed for the hip and the knee.
  
  
  RESULTS
  For pain, key features of pain that are most distressing to people with OA from early to late disease were identified. For function, the reduction of the number of items based on the existing indices continues. For structure, the analysis is also ongoing.
  
  
  CONCLUSIONS
  Preliminary results were presented at OMERACT 8; the final objective will be to combine the 3 domains (pain, function, and structure) and to create a composite index that could define states of severity and "need for total joint replacement," which could be used to evaluate treatment response to disease-modifying drugs in OA clinical trials.
authors.affiliation: Medicine Faculty, Paris 5 René Descartes University; AP-HP, Cochin Hospital, Department of Rheumatology B, Paris, France.
authors.forename: Laure
authors.initials: L
authors.lastname: Gossec
authors.forename: Gillian
authors.initials: G
authors.lastname: Hawker
authors.forename: Aileen M
authors.initials: AM
authors.lastname: Davis
authors.forename: Jean Francis
authors.initials: JF
authors.lastname: Maillefert
authors.forename: L Stefan
authors.initials: LS
authors.lastname: Lohmander
authors.forename: Roy
authors.initials: R
authors.lastname: Altman
authors.forename: Jolanda
authors.initials: J
authors.lastname: Cibere
authors.forename: Philip G
authors.initials: PG
authors.lastname: Conaghan
authors.forename: Marc C
authors.initials: MC
authors.lastname: Hochberg
authors.forename: Joanne M
authors.initials: JM
authors.lastname: Jordan
authors.forename: Jeffrey N
authors.initials: JN
authors.lastname: Katz
authors.forename: Lyn
authors.initials: L
authors.lastname: March
authors.forename: Nizar
authors.initials: N
authors.lastname: Mahomed
authors.forename: Karel
authors.initials: K
authors.lastname: Pavelka
authors.forename: Ewa M
authors.initials: EM
authors.lastname: Roos
authors.forename: Maria E
authors.initials: ME
authors.lastname: Suarez-Almazor
authors.forename: Gustavo
authors.initials: G
authors.lastname: Zanoli
authors.forename: Maxime
authors.initials: M
authors.lastname: Dougados
mesh_terms: D019644:Arthroplasty, Replacement, Hip; D019645:Arthroplasty, Replacement, Knee; D004185:Disability Evaluation; D018450:Disease Progression; D017144:Focus Groups; D006801:Humans; D007391:International Cooperation; D007407:Interviews as Topic; D015207:Osteoarthritis, Hip / Q000175:diagnosis / Q000503:physiopathology* / Q000601:surgery*; D020370:Osteoarthritis, Knee / Q000175:diagnosis / Q000503:physiopathology* / Q000601:surgery*; D017063:Outcome Assessment, Health Care / Q000379:methods; D010147:Pain Measurement; D015203:Reproducibility of Results; D012720:Severity of Illness Index