Abstract
Introduction
The goal of the current study was to determine if SES affects PROMs in patients treated with THA. Specifically, we sought to determine any potential differences between low and high SES patients in pre-surgical PROMs, post-surgical PROMs, and PROM improvement after surgery while controlling for any potential confounding demographic factors.
Methods
Patients were selected from a clinical registry at an urban tertiary academic medical center. All patients undergoing primary THA between January 1, 2000 and April 1, 2016 were eligible for this study. During this period, patients were asked to complete the Harris Hip Score (HHS), Euro-QoL 5 Dimension (EQ-5D), 0–10 Numerical Rating Scale (NRS) Pain, 0–10 NRS Satisfaction (only given postoperatively), the Charnley Classifier, and the University of California Los Angeles (UCLA) Activity Score.
To determine SES, patients were matched by zip code to corresponding median household income as reported by the United States Census Bureau. Patients were then dichotomized into low and high SES groups using 2016 median household income of $57,617 USD as a cutoff point.
Statistical differences between low and high SES patients were determined for demographic factors, preoperative PROMs, postoperative PROMs, and PROM change. Non-parametric variables were tested with the Mann Whitney U test and categorical variables were tested with the Chi squared test.
Multivariate models were created to determine if SES group was independently predictive of achieving a minimal clinically important improvement (MCII) in PROMs (18.0 for HHS, −2.0 for NRS Pain, and 0.92 for UCLA). As potential confounders, we tested body mass index (BMI), preoperative health state from EQ-5D visual analog scale (EQ VAS), age at surgery, preoperative Charnley class, sex, and time between PROMs.
Results
4,580 operations met our basic inclusion criteria, representing a follow-up frequency of 73.5% of 6,235 total captured primary total hip procedures during the study period.
There was no difference between the SES groups in any of the demographics. In every preoperative PROM, low SES patients performed significantly worse than high SES patients. Low SES patients also performed significantly worse on HHS, EQ VAS, and UCLA postoperatively. In contrast, there was no difference improvement for any PROM between the preoperative and postoperative intervals of the two groups. Multivariate models demonstrated that SES is not an independent predictor of achieving an MCII in HHS, NRS Pain, or UCLA Activity when controlling for possible confounders.
Conclusions
We found that while SES is associated with health status, it does not preclude low SES patients from receiving the benefits of THA. We recommend that value-based reimbursement models adjust for SES when evaluating postoperative PROMs.
