The assessment of racial differences in pain and function outcome following knee arthroplasty (KA) has received little attention despite very substantial literature exploring a variety of other prognostic factors. The present study was undertaken to determine whether race was associated with KA outcome after accounting for potential confounding factors.
We conducted a secondary analysis of a randomized clinical trial of 384 participants with moderate-to-high pain catastrophizing who underwent KA. Preoperative measures included race/ethnicity status as well as a variety of potential confounders, including socioeconomic status, comorbidity, and bodily pain. Outcome measures were Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain and function scales as well as performance measures. Linear mixed-effects models compared outcomes over a 1-year follow-up period for African American versus non-African American participants.
WOMAC pain scores differences for African American versus non-African American participants averaged ~2 points in unadjusted analyses and 1-1.5 points in adjusted analyses. In adjusted analyses, follow-up WOMAC function scores differed by 6 points for African Americans compared to non-African Americans (P = 0.002).
African Americans generally had worse pain, function, and performance prior to KA and worse scores after surgery, but differences were small and attenuated by ~25-50% after adjustment for potential confounding. Only WOMAC function scores showed clinically important postsurgical differences in adjusted analyses. Clinicians should be aware that after adjustment for potential confounders, African Americans have approximately equivalent outcomes compared to others, with the exception of WOMAC function score.