Association between pain, radiographic severity, and centrally-mediated symptoms in women with knee osteoarthritis.

OBJECTIVE To examine the relationship between pain, radiographic severity, and a common set of co-occurring centrally-mediated symptoms (fatigue, sleep quality, and depression) in women with knee osteoarthritis. METHODS Participants underwent knee radiographs, and had repeated assessments of pain severity and other centrally-mediated symptoms during a 5-day home monitoring period. To examine associations between pain severity (the average of pain over the home monitoring period), measures of osteoarthritis radiographic severity (Kellgren/Lawrence grade, minimum joint space width), centrally-mediated symptoms, and demographics (age) were used. Symptoms of fatigue, sleep efficiency, and depression were used in a composite measure representing centrally-mediated symptoms. RESULTS Using a series of linear regression models in which each variable was entered hierarchically (n = 54), the final model showed that 27% of the variance in pain severity was explained by age, radiographic severity, and centrally-mediated symptoms. Centrally-mediated symptoms explained an additional 10% of the variance in pain severity after the other 2 variables were entered. CONCLUSION Both radiographic severity and centrally-mediated symptoms were independently and significantly associated with pain severity in women with knee osteoarthritis. In addition to more severe radiographic features, women with higher centrally-mediated symptoms had greater pain severity. Treatments for women with symptomatic knee osteoarthritis may be optimized by addressing both peripheral and central sources of pain.