title: How should worsening in osteoarthritis be defined? Development and initial validation of preliminary criteria for clinical worsening in knee and hip osteoarthritis.
abstract: OBJECTIVE
  There is a need to define and validate measures of clinical worsening in knee and hip osteoarthritis (OA). The objectives of this exploratory project were: (i) to characterize worsening criteria in knee and hip OA using psychometric methods; (ii) to estimate their sensitivity and specificity; and (iii) to validate and compare these criteria with worsening criteria previously described in the literature.
  
  
  METHODS
  An Expert Group reached consensus on 10 sets of worsening criteria to be tested in observational data sets of patients with knee or hip OA who received multimodal conservative treatment. These sets included 219 patients (derivation cohort) and 296 patients (validation cohort). We estimated minimal clinically important worsening (MCIW) values for pain, function, stiffness, and patient global assessment, and tested candidate worsening criteria in the derivation cohort. Finally, using patient judgement, we examined the sensitivity and specificity of literature-based as well as candidate worsening criteria in the validation cohort.
  
  
  RESULTS
  Literature-based worsening criteria were found to have high specificity (range 60-92%) but low sensitivity (range 22-59%). Two out of 10 candidate worsening criteria constructed by the Expert Group showed an acceptable combination of sensitivity and specificity in the derivation cohort, which was confirmed in the validation cohort (ranging from 54% to 65% and 67% to 74%, respectively).
  
  
  CONCLUSIONS
  This is the first study to describe symptomatic worsening criteria based on expert consensus after examining the performance of candidate criteria derived from the literature applied to data in an observational study. The newly proposed worsening criteria show an acceptable combination of sensitivity and specificity.
authors.affiliation: a Department of Rheumatology , Sint Maartenskliniek , Nijmegen , The Netherlands.
authors.forename: Eam
authors.initials: E
authors.lastname: Mahler
authors.affiliation: a Department of Rheumatology , Sint Maartenskliniek , Nijmegen , The Netherlands.
authors.forename: A A
authors.initials: AA
authors.lastname: den Broeder
authors.affiliation: b Division of Rheumatology , Geffen School of Medicine UCLA , Los Angeles , CA , USA.
authors.forename: T G
authors.initials: TG
authors.lastname: Woodworth
authors.affiliation: c Department of Orthopedics , Sint Maartenskliniek , Nijmegen , The Netherlands.
authors.forename: Vjjf
authors.initials: V
authors.lastname: Busch
authors.affiliation: a Department of Rheumatology , Sint Maartenskliniek , Nijmegen , The Netherlands.|d Department of Rheumatology , Radboud University Medical Centre , Nijmegen , The Netherlands.
authors.forename: F H
authors.initials: FH
authors.lastname: van den Hoogen
authors.affiliation: e Department of Rheumatology and Clinical Immunology , University Medical Centre Utrecht , Utrecht , The Netherlands.
authors.forename: Jwj
authors.initials: J
authors.lastname: Bijlsma
authors.affiliation: a Department of Rheumatology , Sint Maartenskliniek , Nijmegen , The Netherlands.
authors.forename: Chm
authors.initials: C
authors.lastname: van den Ende
mesh_terms: D032921:Consensus; D018450:Disease Progression; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009426:Netherlands; D015207:Osteoarthritis, Hip / Q000175:diagnosis*; D020370:Osteoarthritis, Knee / Q000175:diagnosis*; D018579:Patient Selection; D011594:Psychometrics / Q000379:methods / Q000592:standards; D012680:Sensitivity and Specificity; D063189:Symptom Assessment / Q000379:methods / Q000592:standards