Necessary and discretionary activities in knee osteoarthritis: do they mediate the pain-depression relationship?

This study examined direct vs indirect associations of pain and physical function with depression in 369 older adults with osteoarthritis (OA) of the knee. A key focus was the distinction of functional disability in necessary tasks (basic and instrumental activities of daily living) from discretionary, leisure activities.

A naturalistic longitudinal study examined effects of demographic variables, indicators of arthritis status, general health, pain, and several measures of functional disability upon depressive symptoms at baseline and 1 year later.

Participants with diagnosed knee OA were recruited from rheumatological and general geriatric outpatient clinics, as well as public service announcements.

Depressive symptoms, measured with the Center for Epidemiologic Studies Depression scale.

At baseline, the relationships of depression with functional disability and activity limitation were wholly mediated by pain. In contrast, activity participation was independently linked with depression, even controlling health and demographic variables. A 1-year follow-up revealed that depressive symptoms increased with increasing health problems, and with reduction in activity participation over time. Having and retaining favorite pastimes were also associated with reduced depressive symptomatology at baseline and follow-up, respectively.

These data highlight the disease-specific nature of paths among depression, pain, and disability, and the importance of considering discretionary as well as necessary activities in evaluating effects of pain upon quality of life.