title: The association between low back pain and osteoarthritis of the hip and knee: a population-based cohort study.
abstract: OBJECTIVE
  The purpose of this study was to determine whether prevalent self-reported back pain predicts future osteoarthritis-related pain and disability in individuals with hip and knee osteoarthritis (OA).
  
  
  METHODS
  We studied a population-based cohort of Ontario residents who were 55 years or older and reported symptomatic hip/knee OA at baseline (between 1996 and 1998). The sample was followed-up between 2000 and 2001. We used multivariable linear regression to model the association between baseline back pain and pain and disability (Western Ontario and McMaster Universities Osteoarthritis Index scores) at follow-up while controlling for confounders.
  
  
  RESULTS
  Of the 983 participants, 58% of the cohort reported low back pain at baseline. Baseline low back pain predicted higher hip and/or knee OA-related pain and disability at follow-up (beta = 2.49; 95% confidence interval [CI], 0.4-4.6; P = .023). However, this association varied with the location of OA. After controlling for confounders, the association was strong for individuals with hip OA (beta = 11.41; 95% CI, 5.1-17.7; P = .001). However, low back pain was not associated with pain and disability in individuals with knee OA (beta = 0; 95% CI -3.39 to 3.39; P = .998).
  
  
  CONCLUSIONS
  In a cohort of individuals with OA of the hip or knee, we found that low back pain predicted subsequent OA-related pain and disability in those with hip disease, but not knee disease. Our study provides valuable prognostic information to clinicians involved in the management of patients with OA of the hip and knee.
authors.affiliation: Department of Health Policy, Management and Evaluation, Faculty of Medicine, University of Toronto, Toronto Western Research Institute, University Health Network, 750 Dundas Street W., Toronto, Ontario, Canada. mstupar@uhnresearch.ca
authors.forename: Maja
authors.initials: M
authors.lastname: Stupar
authors.forename: Pierre
authors.initials: P
authors.lastname: Côté
authors.forename: Melissa R
authors.initials: MR
authors.lastname: French
authors.forename: Gillian A
authors.initials: GA
authors.lastname: Hawker
mesh_terms: D000368:Aged; D015331:Cohort Studies; D005260:Female; D006801:Humans; D017116:Low Back Pain / Q000150:complications*; D008297:Male; D015207:Osteoarthritis, Hip / Q000150:complications*; D020370:Osteoarthritis, Knee / Q000150:complications*