Frailty, Race/Ethnicity, Functional Status, and Adverse Outcomes After Total Hip/Knee Arthroplasty: A Moderation Analysis

Background: Although frailty has been shown to be associated with adverse outcomes in patients undergoing total hip arthroplasty (THA) and total knee arthroplasty (TKA), prior studies have not examined how race/ethnicity might moderate these associations. We aimed to assess race/ethnicity as a potential moderator of the associations of frailty and functional status with arthroplasty outcomes. Methods: The National Surgical Quality Improvement Program was queried for patients who underwent THA or TKA from 2011 to 2017. Frailty was assessed using the modified frailty index. Regression analyses were conducted to examine associations connecting frailty/functional status with 30-day readmission, adverse discharge, and length of stay (LOS). Further analyses were conducted to investigate race/ethnicity as a potential moderator of these relationships. Results: We identified 219,143 TKA and 130,022 THA patients. Frailty and nonindependent functional status were positively associated with all outcomes (P <.001). Compared to White non-Hispanic patients, Black non-Hispanic patients had higher odds for all outcomes after TKA (P <.001) and for adverse discharge/longer LOS after THA (P <.001). Similar associations were observed for Hispanics for the adverse discharge/LOS outcomes. Race/ethnicity moderated the effects of frailty in TKA for all outcomes and in THA for adverse discharge/LOS. Race/ethnicity moderated the effects of nonindependent function in TKA for adverse discharge/LOS and on LOS alone for THA. Conclusion: Disparities for Black non-Hispanic and Hispanic patients persist for readmission, adverse discharge, and LOS. However, the effects of increasing frailty and nonindependent functional status on these outcomes were the most pronounced among White non-Hispanic patients.