title: Psychological health impact on 2-year changes in pain and function in persons with knee pain: data from the Osteoarthritis Initiative.
abstract: OBJECTIVE
  We determined whether baseline depressive symptoms, knee-related confidence and general psychological distress influenced changes in pain and function during 2 years of follow-up.
  
  
  METHODS
  We included persons in the Osteoarthritis Initiative (OAI) dataset with baseline pain of 1 or greater on a 0-10 scale in at least one knee and no knee or hip surgery during the 2-year follow-up (n=3407). The four outcome variables were repeated chair standing, 20 m walk and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) Pain and Disability. Linear mixed effects models assessed the association of each mental health variable with the yearly change in each baseline adjusted outcome measure after controlling for covariates.
  
  
  RESULTS
  Depressive symptoms were significantly predictive of worsening in most outcomes. The magnitude of worsening predicted for each year was small. For example, the dichotomized WOMAC Pain model indicated that depressed persons experience more rapid worsening than non-depressed persons at an average rate of 0.59 WOMAC points per year (95% CI 0.176, 1.013, P=0.005). Similar significant but very small effects of depressive symptoms on other outcomes were observed. Knee confidence was not predictive of change. General psychological distress was predictive of change in 20-m walk and WOMAC Pain.
  
  
  CONCLUSIONS
  The most consistent psychological predictor of yearly worsening was baseline depressive symptoms. Although a statistically robust predictor of outcome, given that change was very small and highly dependent on baseline status, our results indicate that a considerable degree of persistent depressive symptoms would be required to have a meaningful effect on future self-reported outcome.
authors: Department of Physical Therapy, Virginia Commonwealth University, Richmond, VA 23298-0224, USA. dlriddle@vcu.edu
authors: D L
authors: DL
authors: Riddle
authors: X
authors: X
authors: Kong
authors: G K
authors: GK
authors: Fitzgerald
mesh_terms: D000368:Aged; D003863:Depression / Q000209:etiology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D009043:Motor Activity; D020370:Osteoarthritis, Knee / Q000150:complications / Q000503:physiopathology / Q000523:psychology*; D010146:Pain / Q000150:complications / Q000523:psychology*; D010147:Pain Measurement; D011446:Prospective Studies; D057566:Self Report; D013315:Stress, Psychological; D016138:Walking