title: Pain as a mediator of sleep problems in arthritis and other chronic conditions.
abstract: OBJECTIVE
  To examine the associations between arthritis and insomnia symptoms and unrefreshing sleep, as well as the role of pain as a mediator of these relationships.
  
  
  METHODS
  Analyses were conducted on the cross-sectional, nationally representative, weighted sample of adults > or =18 years of age (n = 118,336) in the 2000/2001 Canadian Community Health Survey. Four logistic regression models were estimated for each sleep problem (model 1: arthritis only; model 2: model 1 + sociodemographic characteristics, lifestyle factors, and other chronic conditions; model 3: model 2 + mental health [stress, depression]; and model 4: model 3 + pain). Mediation by pain was quantified by the percentage change in the effect of arthritis on a particular sleep problem by comparing models 3 and 4.
  
  
  RESULTS
  The prevalence of insomnia symptoms and unrefreshing sleep in persons with arthritis was 24.8% and 11.9%, respectively. These estimates are twice as high as those for persons without arthritis. In multivariate regression analyses, the addition of pain decreased the effect of arthritis by 53% (insomnia symptoms) and 64% (unrefreshing sleep). The effect of arthritis was still statistically significant in these models, suggesting that pain is a partial mediator of these relationships.
  
  
  CONCLUSIONS
  Insomnia symptoms and unrefreshing sleep affect a considerable proportion of individuals with arthritis. Pain mediates a substantial amount of the relationship between arthritis and sleep problems. Better pain management could significantly improve sleep in individuals with arthritis.
authors.affiliation: University of Toronto, and Toronto Western Research Institute, University Health Network, Toronto, Ontario, Canada. dpower@uhnres.utoronto.ca
authors.forename: J Denise
authors.initials: JD
authors.lastname: Power
authors.forename: Anthony V
authors.initials: AV
authors.lastname: Perruccio
authors.forename: Elizabeth M
authors.initials: EM
authors.lastname: Badley
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001168:Arthritis / Q000453:epidemiology* / Q000503:physiopathology; D002170:Canada / Q000453:epidemiology; D015897:Comorbidity; D003430:Cross-Sectional Studies; D020920:Dyssomnias / Q000175:diagnosis / Q000453:epidemiology*; D005260:Female; D006801:Humans; D008019:Life Style; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D010146:Pain / Q000453:epidemiology*; D007319:Sleep Initiation and Maintenance Disorders / Q000175:diagnosis / Q000453:epidemiology*