Race and gender disparities in physical function before and after total hip arthroplasty: a retrospective analysis

Abstract

Purpose: Race and gender disparities in rates of total joint replacement surgery in the United States have been well-documented, and it appears that socioeconomic status plays a role in the generation of such disparities. However, little research exists regarding whether disparities persist amongst those who undergo arthroplasty surgery. The purpose of this study was to investigate physical function in a database of individuals who underwent total hip arthroplasty (THA) and identify potential disparities by race, gender, and socioeconomic status. Methods: We retrospectively analyzed electronic chart data of individuals who underwent THA with a single surgeon at a large urban hospital between January 2013 and March 2016. Individuals were included who underwent unilateral THA for a primary diagnosis of osteoarthritis. For those who received staged bilateral THAs during the study period, data from their first arthroplasty surgery only were included. Demographic data were retrieved, including age, sex, race, ethnicity, health insurance status, and census tract of residence. The proportion of households with incomes below the United States federal poverty level (FPL) in each individual's census tract of residence was used as a marker for socioeconomic status. Medical comorbidities were collected and summed using the Functional Comorbidity Index (FCI). Self-reported physical function was measured using the Harris Hip Score (HHS) pre-operatively and at six months post-operatively. Descriptive statistics were used to summarize sample demographics. T-tests were used to compare pre-operative and post-operative physical function between men and women, between white/Caucasian and black/African-American patients, and between patients living in low-poverty and high-poverty census tracts. Low-poverty census tracts were defined as those in which fewer than 20% of household incomes are below the federal poverty level (FPL), and high-poverty census tracts were defined as those in which greater than 20% of household incomes fall below FPL. Results: The sample of 271 individuals contained an even distribution of men (49.4%) and women (49.4%). On average, patients were slightly less than retirement age (mean age 63.2 years, SD 11.9) and had relatively low number of comorbidities (mean FCI 3.3, SD 1.8). A majority of patients (60.1%) had private health insurance, with smaller proportions using Medicare (22.1%), Medicaid (5.5%), or other types of insurance (12.2%). 86.7% of patients in the sample were white/Caucasian and non-Hispanic; 11.1% were black/African-American and non-Hispanic; fewer than one percent were Hispanic ethnicity and/or any other race. 83.0% (n = 225) of patients lived in low-poverty neighborhoods, while 10.7% (n = 29) lived in high-poverty neighborhoods (census tracts of residence for the remaining 17 patients were unable to be determined from electronic chart data). At baseline, men (mean HHS 46.3, SD 11.5) were functioning significantly better than women (mean 42.4, SD 13.7), P = .03. However, this difference was no longer significant at six-month follow-up (mean HHS for men 79.8, SD 16.7; mean HHS for women 77.5, SD 16.3), P = .41. At baseline, black patients (mean HHS 38.8, SD 13.3) were functioning significantly poorer than white patients (mean HHS 45.3, SD 12.4), P = .02. This difference persisted at six-month follow-up: mean HHS 79.7 (SD 15.8) for white patients and 68.0 (SD 1.92) for black patients, P = .03. There were no statistically significant differences between patients living in high-poverty neighborhoods and those in low-poverty neighborhoods at baseline (high-poverty mean HHS 39.1, SD 15.7; low-poverty mean HHS 45.2, SD 12.0) or at six-month follow-up (high-poverty mean HHS 69.4, SD 20.2; low-poverty mean HHS 79.8, SD 15.7). However, the relatively low proportion of patients residing in low-poverty census tracts resulted in low statistical power to detect such differences. Conclusions: In this sample of 271 individuals who underwent unilateral THA, women and black patients were functioning significantly poorer than men and white patients pre-operatively. At six months post-operatively, the significant difference in physical function between white and black patients persisted. Medical and rehabilitation providers and community organizations should be aware that undergoing THA surgery may not fully resolve existing disparities in physical function in this population.