Measurement of illness perception and behaviour along a continuum of symptomatic knee osteoarthritis: a transdisciplinary approach

Objectives: A multifactorial approach is recommended for the identification/diagnosis, prognosis, and treatment of pain in knee osteoarthritis (OA). One aspect of this approach includes illness perception and behaviour. The purpose of this thesis was to investigate the measurement of illness perception and behaviour along a continuum of symptomatic knee OA, starting from the early symptoms of knee OA. Methods: Three studies were conducted to fulfill this purpose. The first study was a scoping review that applied an interpretative analysis to validated measures that had been used to assess people with knee pain and/or knee OA. Second was the construct validation of a measure of illness perception and behaviour in people with early symptoms of knee OA and confirmed knee OA. Third was a study of a rat model of post-traumatic knee OA that was undertaken to identify behavioural measures that were significantly different between rats with and without knee OA. Results: The scoping review identified 16 validated measures that capture components of illness perception and behaviour. Only one measure, the Questionnaire to Identify Knee Symptoms (QuIKS), capture all four components of illness perception and behaviour. In the second study, a version of the QuIKS called the QuIKS-R was found to be unidimensional and to provide interval-level scaling of illness perception and behaviour. In the third study, ipsilateral weight-bearing deficit and vertical activity limitations were identified as two behavioural measures that differed between the rat model of post-traumatic knee OA and control groups. Conclusions: The three studies in this thesis identified measures that could be important in advancing the identification and care of people with symptoms of knee OA, in terms of clinical care, clinical research with humans and preclinical research with the rat model of post-traumatic knee OA