title: The association of body-mass index and depressed mood with knee pain and activity limitations in knee osteoarthritis: results from the Amsterdam osteoarthritis cohort.
abstract: BACKGROUND
  Body-mass index (BMI) and depressed mood are both positively associated with pain and activity limitations in knee osteoarthritis (OA), and are interrelated. The aims of the present study were: 1) to assess whether BMI and depressed mood are independently associated with knee pain and activity limitations; and 2) to compare the relative contributions of BMI and depressed mood to knee pain and activity limitations.
  
  
  METHODS
  A cross-sectional study in 294 patients with clinical knee OA. Regression analyses were performed with knee pain or activity limitations (self-reported and performance-based) as dependent variables, and BMI and depressed mood as independent variables. All analyses were adjusted for age, gender, marital status, education level, radiographic OA and comorbidity. Dominance analyses were performed to examine the relative contributions of BMI and depressed mood to knee pain and activity limitations.
  
  
  RESULTS
  BMI and depressed mood were positively and independently associated with knee pain and activity limitations. BMI and depressed mood explained small parts (3.0% and 2.3%, respectively) of variance in knee pain. BMI explained a substantial part of variance in both self-reported (9.8%) and performance-based (20.4%) activity limitations, while depressed mood explained a small part of variance (3.1% in self-reported and 2.6% in performance-based activity limitations).
  
  
  CONCLUSIONS
  In patients with knee OA both BMI and depressed mood seem to be independently associated with knee pain and activity limitations. The contribution of BMI to activity limitations is most substantial, thereby offering a relevant target for interventions.
authors.affiliation: Amsterdam Rehabilitation Research Centre | Reade, PO Box 58271, 1040 HG Amsterdam, The Netherlands. j.holla@reade.nl.
authors.forename: Jasmijn F M
authors.initials: JF
authors.lastname: Holla
authors.forename: Marike
authors.initials: M
authors.lastname: van der Leeden
authors.forename: Dirk L
authors.initials: DL
authors.lastname: Knol
authors.forename: Leo D
authors.initials: LD
authors.lastname: Roorda
authors.forename: Martin
authors.initials: M
authors.lastname: van der Esch
authors.forename: Ramon E
authors.initials: RE
authors.lastname: Voorneman
authors.forename: Willem F
authors.initials: WF
authors.lastname: Lems
authors.forename: Joost
authors.initials: J
authors.lastname: Dekker
mesh_terms: D000368:Aged; D015992:Body Mass Index; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D003863:Depression / Q000150:complications*; D015444:Exercise; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009426:Netherlands / Q000453:epidemiology; D020370:Osteoarthritis, Knee / Q000150:complications* / Q000453:epidemiology / Q000523:psychology*; D050177:Overweight / Q000150:complications*; D010146:Pain / Q000209:etiology*