title: Activity-Modifying Behaviour Mediates the Relationship between Pain Severity and Activity Limitations among Adults with Emergent Knee Pain.
abstract: OBJECTIVE
  To determine whether activity-modifying behaviour mediates the relationship between the severity of knee pain and each of physical function and knee-related quality of life.
  
  
  METHODS
  A total of 105 participants with medial knee pain and no diagnosis of knee osteoarthritis (mean age 52.2 [SD 6.7] y) completed two self-report questionnaires. The Questionnaire to Identify Knee Symptoms assessed activity-modifying behaviour; the Knee injury and Osteoarthritis Outcome Score assessed pain severity, physical function, and knee-related quality of life. Simple mediation analysis was performed using linear regression.
  
  
  RESULTS
  The unstandardized regression coefficient for activity-modifying behaviour revealed partial mediation of the effect of pain severity on physical function (0.31 (SE 0.09), p<0.001) and on knee-related quality of life (0.24 (SE 0.07), p<0.001). After accounting for activity-modifying behaviour, the variance in physical function that was explained by pain decreased from 45% to 15%, and the variance in knee-related quality of life that was explained by pain decreased from 64% to 25%.
  
  
  CONCLUSIONS
  Activity-modifying behaviour partially mediates the relationship between pain severity and physical function and between pain severity and knee-related quality of life. Activity-modifying behaviour may thus counteract the impact of knee pain on physical function and knee-related quality of life, which explains why it is used by people with emergent knee pain.
authors.affiliation: Graduate Program in Health and Rehabilitation Sciences, Faculty of Health Sciences ; School of Physical Therapy.
authors.forename: Clayon B
authors.initials: CB
authors.lastname: Hamilton
authors.affiliation: School of Physical Therapy ; School of Rehabilitation Science, McMaster University, Hamilton, Ont.
authors.forename: Monica R
authors.initials: MR
authors.lastname: Maly
authors.affiliation: Graduate Program in Health and Rehabilitation Sciences, Faculty of Health Sciences.
authors.forename: Jessica M
authors.initials: JM
authors.lastname: Clark
authors.affiliation: Department of Epidemiology and Biostatistics.
authors.forename: Mark
authors.initials: M
authors.lastname: Speechley
authors.affiliation: Department of Family Medicine, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, Ont.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Petrella
authors.affiliation: Graduate Program in Health and Rehabilitation Sciences, Faculty of Health Sciences ; School of Physical Therapy ; Department of Epidemiology and Biostatistics.
authors.forename: Bert M
authors.initials: BM
authors.lastname: Chesworth
keywords: activities of daily living; arthralgia; behaviour; knee; quality of life