title: Clinical phenotypes in patients with knee osteoarthritis: a study in the Amsterdam osteoarthritis cohort.
abstract: OBJECTIVE
  To identify and validate previously established phenotypes of knee osteoarthritis (OA) based on similarities in clinical patient characteristics.
  
  
  METHODS
  Knee OA patients (N = 551) from the Amsterdam OA (AMS-OA) cohort provided data. Four clinical patient characteristics were assessed: upper leg muscle strength, body mass index (BMI), radiographic severity (Kellgren/Lawrence [KL] grade), and depressive mood (the Hospital Anxiety and Depression Scale [HADS] questionnaire). Cluster analysis was performed to identify the optimal number of phenotypes. Differences in clinical characteristics between the phenotypes were analyzed with ANOVA.
  
  
  RESULTS
  Cluster analysis identified five phenotypes of knee OA patients: "minimal joint disease phenotype", "strong muscle strength phenotype", "severe radiographic OA phenotype", "obese phenotype", and "depressive mood phenotype".
  
  
  CONCLUSIONS
  Among patients with knee OA, five phenotypes were identified based on four clinical characteristics. To a high degree, the results are a replication of earlier findings in the OA Initiative, indicating that these five phenotypes seem a stable, valid, and clinically relevant finding.
authors.affiliation: Amsterdam Rehabilitation Research Center, Reade, Amsterdam, The Netherlands. Electronic address: m.vd.esch@reade.nl.
authors.forename: M
authors.initials: M
authors.lastname: van der Esch
authors.affiliation: Amsterdam Rehabilitation Research Center, Reade, Amsterdam, The Netherlands.
authors.forename: J
authors.initials: J
authors.lastname: Knoop
authors.affiliation: Amsterdam Rehabilitation Research Center, Reade, Amsterdam, The Netherlands; VU University Medical Center, Department of Rehabilitation Medicine, Amsterdam, The Netherlands; VU University Medical Center, EMGO Institute for Health and Care Research, Amsterdam, The Netherlands.
authors.forename: M
authors.initials: M
authors.lastname: van der Leeden
authors.affiliation: Amsterdam Rehabilitation Research Center, Reade, Amsterdam, The Netherlands.
authors.forename: L D
authors.initials: LD
authors.lastname: Roorda
authors.affiliation: VU University Medical Center, Department of Rheumatology, Amsterdam, The Netherlands; Reade, Department of Rheumatology, Amsterdam, The Netherlands.
authors.forename: W F
authors.initials: WF
authors.lastname: Lems
authors.affiliation: VU University Medical Center, EMGO Institute for Health and Care Research, Amsterdam, The Netherlands; VU University Medical Center, Department of Epidemiology and Biostatistics, Amsterdam, The Netherlands.
authors.forename: D L
authors.initials: DL
authors.lastname: Knol
authors.affiliation: VU University Medical Center, Department of Rehabilitation Medicine, Amsterdam, The Netherlands; VU University Medical Center, EMGO Institute for Health and Care Research, Amsterdam, The Netherlands; VU University Medical Center, Department of Psychiatry, Amsterdam, The Netherlands.
authors.forename: J
authors.initials: J
authors.lastname: Dekker
mesh_terms: D000368:Aged; D015992:Body Mass Index; D016000:Cluster Analysis; D015331:Cohort Studies; D015897:Comorbidity; D003430:Cross-Sectional Studies; D003863:Depression / Q000523:psychology*; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D053580:Muscle Strength / Q000502:physiology*; D009426:Netherlands; D009765:Obesity / Q000150:complications* / Q000503:physiopathology; D020370:Osteoarthritis, Knee / Q000145:classification / Q000503:physiopathology* / Q000523:psychology*; D010641:Phenotype; D011859:Radiography; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D011795:Surveys and Questionnaires
keywords: Depressive disorder [Mesh]; Knee [Mesh]; Muscle strength [Mesh]; Obesity [Mesh]; Osteoarthritis; Phenotype [Mesh]