Illness perceptions in patients with osteoarthritis: change over time and association with disability.

OBJECTIVE To investigate changes in illness perceptions in patients with osteoarthritis (OA) and the association of those changes with disability, and to determine the predictive value of illness perceptions in disability. METHODS Illness perceptions and disability were measured at baseline and after 6 years in 241 patients with OA at multiple sites (mean age 59.0 years, 82.2% women) using the revised Illness Perception Questionnaire (IPQ-R) and the Health Assessment Questionnaire (HAQ), respectively. Mean changes for each IPQ-R dimension were reported and related to progression of disability, defined as the highest quartile of HAQ score change. The predictive value of baseline illness perceptions in disability at 6 years (with high disability defined as the highest quartile of HAQ score) was assessed using logistic regression. RESULTS Illness perceptions changed over time, and these changes were related to the progression of disability. Patients with progression of disability had an increase in symptoms attributed to OA, perceived consequences, perceived disease chronicity, negative emotions associated with OA and beliefs about immunity as causal factor, and a decrease in perceived control and understanding of OA compared with patients without progression of disability. Moreover, a higher number of symptoms attributed to OA, less perceived control, and more perceived consequences of OA at baseline were predictive of high disability after 6 years. CONCLUSION Illness perceptions in patients with OA changed over time, and these changes were related to outcome. Moreover, illness perceptions were predictive of disability. This may imply that interventions aimed at changing illness perceptions can contribute to better functional outcome.