title: Three trajectories of activity limitations in early symptomatic knee osteoarthritis: a 5-year follow-up study.
abstract: OBJECTIVE
  Knee osteoarthritis (OA) is a leading cause of activity limitations. The knee OA population is likely to consist of subgroups. The aim of the present study was to identify homogeneous subgroups with distinct trajectories of activity limitations in patients with early symptomatic knee OA and to describe characteristics of these subgroups.
  
  
  METHODS
  Follow-up data over a period of 5 years of 697 participants with early symptomatic knee OA from the Cohort Hip and Cohort Knee (CHECK) were used. Activity limitations were measured yearly with the Western Ontario and McMaster Universities Osteoarthritis Index. Latent class growth analyses identified homogeneous subgroups with distinct trajectories of activity limitations. Multivariable regression analyses examined differences in characteristics between the subgroups.
  
  
  RESULTS
  Three subgroups were identified. Participants in Subgroup 1 ('good outcome'; n=330) developed or displayed slight activity limitations over time. Participants in Subgroup 2 ('moderate outcome'; n=257) developed or displayed moderate activity limitations over time. Participants in subgroup 3 ('poor outcome'; n=110) developed or displayed severe activity limitations over time. Compared with the 'good outcome' subgroup, the 'moderate outcome' and 'poor outcome' subgroups were characterised by: younger age, higher body mass index, greater pain, bony tenderness, reduced knee flexion, hip pain, osteophytosis, ≥3 comorbidities, lower vitality or avoidance of activities.
  
  
  CONCLUSIONS
  Based on the 5-year course of activity limitations, we identified homogeneous subgroups of knee OA patients with good, moderate or poor outcome. Characteristics of these subgroups were consistent with existing knowledge on prognostic factors regarding activity limitations, which supports the validity of this classification.
authors.affiliation: Amsterdam Rehabilitation Research Centre, Reade, Amsterdam, The Netherlands.
authors.forename: Jasmijn F M
authors.initials: JF
authors.lastname: Holla
authors.affiliation: Amsterdam Rehabilitation Research Centre, Reade, Amsterdam, The Netherlands Department of Rehabilitation Medicine, VU University Medical Centre, Amsterdam, The Netherlands EMGO Institute for Health and Care Research, VU University Medical Centre, Amsterdam, The Netherlands.
authors.forename: Marike
authors.initials: M
authors.lastname: van der Leeden
authors.affiliation: EMGO Institute for Health and Care Research, VU University Medical Centre, Amsterdam, The Netherlands Department of Epidemiology and Biostatistics, VU University Medical Centre, Amsterdam, The Netherlands.
authors.forename: Martijn W
authors.initials: MW
authors.lastname: Heymans
authors.affiliation: Amsterdam Rehabilitation Research Centre, Reade, Amsterdam, The Netherlands.
authors.forename: Leo D
authors.initials: LD
authors.lastname: Roorda
authors.affiliation: Department of General Practice, Erasmus MC, University Medical Centre, Rotterdam, The Netherlands Department of Orthopaedics, Erasmus MC, University Medical Centre, Rotterdam, The Netherlands.
authors.forename: Sita M A
authors.initials: SM
authors.lastname: Bierma-Zeinstra
authors.affiliation: Department of Epidemiology and Biostatistics, VU University Medical Centre, Amsterdam, The Netherlands Department of Rheumatology, VU University Medical Centre, Amsterdam, The Netherlands.
authors.forename: Maarten
authors.initials: M
authors.lastname: Boers
authors.affiliation: Department of Rheumatology, VU University Medical Centre, Amsterdam, The Netherlands Jan van Breemen Research Institute, Reade, Amsterdam, The Netherlands.
authors.forename: Willem F
authors.initials: WF
authors.lastname: Lems
authors.affiliation: Institute for Applied Health Research and School of Health and Life Sciences, Glasgow Caledonian University, Glasgow, Scotland, UK.
authors.forename: Martijn Pm
authors.initials: MP
authors.lastname: Steultjens
authors.affiliation: Amsterdam Rehabilitation Research Centre, Reade, Amsterdam, The Netherlands Department of Rehabilitation Medicine, VU University Medical Centre, Amsterdam, The Netherlands EMGO Institute for Health and Care Research, VU University Medical Centre, Amsterdam, The Netherlands Department of Psychiatry, VU University Medical Centre, Amsterdam, The Netherlands.
authors.forename: Joost
authors.initials: J
authors.lastname: Dekker
mesh_terms: D000203:Activities of Daily Living; D000367:Age Factors; D000368:Aged; D018771:Arthralgia / Q000209:etiology; D015992:Body Mass Index; D015331:Cohort Studies; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D051346:Mobility Limitation; D015999:Multivariate Analysis; D020370:Osteoarthritis, Knee / Q000150:complications / Q000000981:diagnostic imaging / Q000503:physiopathology*; D054850:Osteophyte / Q000000981:diagnostic imaging; D050177:Overweight / Q000150:complications; D011859:Radiography; D016059:Range of Motion, Articular; D012307:Risk Factors
keywords: Epidemiology; Knee Osteoarthritis; Rehabilitation