Racial differences in self-reported pain and function among individuals with radiographic hip and knee osteoarthritis: the Johnston County Osteoarthritis Project.

OBJECTIVE: This study compared pain and function among African Americans and Caucasian with radiographic hip and/or knee osteoarthritis (OA), controlling for radiographic severity and other patient characteristics.
METHODS: Participants were 1368 individuals (32% African American) from the Johnston County Osteoarthritis Project with only knee OA, only hip OA, and both knee and hip OA. Linear regression models examined racial differences in Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) total scores and pain and function subscales, adjusting for radiographic severity, age, gender, education, body mass index (BMI), depressive symptoms, and WOMAC pain (last variable in models of function).
RESULTS: Among those with only knee OA, African Americans had significantly worse mean WOMAC total scores than Caucasian (32.8 vs 24.3, P<0.001), and worse pain and function scores (P<0.001). Racial differences in WOMAC total, pain, and function scores persisted when controlling for radiographic severity and demographic factors but were not significant when also controlling for BMI and depressive symptoms. In models of WOMAC function, pain was the most strongly associated variable and substantially reduced the association of race with function. There were no racial differences in WOMAC scores among those with only hip OA or with both knee and hip OA.
CONCLUSION: Among participants with knee OA, racial differences in pain and function may be explained by BMI and depressive symptoms, and racial differences in function may also be largely influenced by pain. Improving management of weight and depressive symptoms may be key steps toward reducing racial disparities in knee OA symptoms.