Background/Purpose: While risk of knee osteoarthritis (OA) is higher among black than white individuals, the rate of knee replacement—an effective treatment for end-stage OA among blacks is lower than among whites. Identifying mechanisms of racial disparity in utilization of knee replacement would help toward development of innovative programs or interventions to reduce disparities and improve OA care in blacks. We compared the risk of knee replacement between black and white individuals and assessed the extent of which the difference in risk of knee replacement was accounted for by several potential mediators.

Methods: Data on race, age, sex, education, family income, and health insurance at baseline examination as well as incident knee replacement during the follow-up were obtained among participants in the Osteoarthritis Initiative, which is a multicenter prospective cohort study of participants with or at high risk of knee OA. First, we compared the risk of knee replacement between blacks and whites using generalized estimating equations, adjusting for age and sex. Then, we estimated the indirect effect of race on the risk of knee replacement mediated through education, income and health insurance using marginal structural model.

Results: Of 4,057 participants (8,114 knees) in the OAI, 3,368 (83.0%) were white (mean age:61.5 years; women: 54.9%, ≥college education: 87.6%, income< $50000/year: 33.3%, and health insurance coverage: 89.6%) and 689 (17.0%) were black (mean age: 58.9 years; women: 68.5%, ≥college education: 73.4%, income< $50000/year: 61.8%, and health insurance coverage: 85.5%). During the follow-up period, 341 (10.1%) whites and 43 (6.2%) blacks have knee replacement therapy. Compared with whites an age-sex-adjusted odds ratio (OR) of knee replacement for blacks was 0.63 (95% Confidence Interval [CI]: 0.45-0.88). In the multiple mediation analysis, the natural direct effect of race on knee replacement was 0.71 (95% CI: 0.49-1.04), and the natural indirect effect through income and health insurance were 0.93 (95% CI: 0.87-1.00) and 0.97 (95% CI: 0.95-0.99), with each of these mediators explaining 20.6% and 9.6% of risk of knee replacement between two racial groups, respectively. (see Table 1).

Conclusion:

Blacks were less likely to have knee replacement than whites, indicating racial disparities in the utilization of knee replacement. Such a disparity was partially attributed to the difference in income and health insurance between two racial groups. Future studies evaluating how perception and willingness on knee replacement mediate the effect of race on knee replacement are warranted.

Table 1. Results of Multiple Mediation-analysis of the Association between Race (black versus white) and Utilization of Knee Replacement

OR, Odds Ratio; 95% CI, 95% Confidence Interval

*OR was adjusted for age and sex

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/racial-disparities-in-utilization-of-knee-replacement-data-from-the-osteoarthritis-initiative/