Black and Hispanic Patients Do Not Stay Longer After Primary Total Knee Arthroplasty: Results From an Urban Center Serving a Predominantly Minority Cohort
Authors: Zvi Yoav S. , Sharfman Zachary T. , Loloi Jeremy , Seref-Ferlengez Zeynep , Lo Yungtai , Tiwari Bharat , Kim Sun Jin 
Published: February 2022

Introduction:
Previous reports identified minority race/ethnicity to be an independent risk factor for prolonged length of stay (LOS); however, these cohorts consisted of predominantly White patients. This study sought to evaluate minority status as an independent risk factor for prolonged LOS after primary total knee arthroplasty (TKA) in a predominantly Hispanic and Black cohort.

Methods:
This was a retrospective study using an institutional database of patients who underwent primary TKA between the years 2016 and 2019. Demographic and socioeconomic data, smoking, body mass index (BMI), medical comorbidities, discharge disposition, and 30-day readmission rates were collected. Patients were first categorized into racial/ethnic groups (Hispanic, Black, or White). An univariate analysis was performed comparing patient characteristics between racial/ethnic groups using the Wilcoxon rank sum, chi-squared, and Fisher exact tests. We then categorized patients into two groups—normal LOS (discharged on postoperative day 1 to 2) and prolonged LOS (discharged after postoperative day 2). An univariate analysis was again performed comparing patient characteristics between LOS groups using Wilcoxon rank sum, chi-squared, and Fisher exact tests. After identifying risk factors markedly associated with LOS, a multivariate logistic regression analysis was performed to identify independent risk factors for prolonged LOS.

Results:
A total of 3,093 patients were included—47.9% Hispanic and 38.3% Black. Mean LOS was 2.9 ± 1.6 days. An univariate analysis found race/ethnicity, age, low socioeconomic status (SES), discharge disposition, insurance type, weekday of surgery, BMI >40, smoking, increased American Society of Anesthesiologists (ASA)/Charlson Comorbidity Index (CCI) and several medical comorbidities to be associated with prolonged LOS (P < 0.05). A multivariate logistic regression analysis found Black and Hispanic patients were less likely to have prolonged LOS after adjusting for associated risk factors. White race/ethnicity, nonhome discharge, low SES, weekday of surgery, smoking, BMI >40, and increased ASA and CCI were identified as independent risk factors for prolonged LOS (P < 0.05). The overall 30-day readmission rate was 3.6%, with no notable difference between racial/ethnic and LOS groups (P = 0.98 and P = 0.78).

Conclusion:
In contrast to previous reports, our study found that after adjusting for associated risk factors, minority patients do not have prolonged LOS after primary TKA in an urban, socioeconomically disadvantaged, predominantly minority patient cohort. White race/ethnicity, nonhome discharge, low SES, weekday of surgery, smoking, BMI >40, increased CCI, and ASA were all found to be independent risk factors for prolonged LOS. These findings highlight the need to further investigate the role of race/ethnicity on LOS after primary TKA using large-scale, randomized controlled trials with equally represented patient cohorts.