# Social inequalities in patient outcomes after total hip replacement surgery for osteoarthritis in England: A population-based cohort study of the National Joint Registry

## TL;DR

This study finds that patients in more deprived areas of England have worse outcomes after hip replacement surgery compared to those in less deprived areas.

## Contribution

The study provides the first comprehensive analysis of socioeconomic inequalities in a wide range of THR outcomes using national registry data over 11 years.

## Key findings

- Patients from the most deprived areas had higher 90-day mortality, complications, rehospitalisation, and reoperation rates after THR.
- Those from deprived areas reported significantly poorer patient-reported hip function scores after surgery.
- There was no significant difference in 5-year revision rates across deprivation levels.

## Abstract

Reducing health inequalities is of national importance. Total hip replacement (THR) is a commonly used elective surgical procedure. Few studies have examined area-level inequalities for a wide range of outcomes following THR. The aim of this study is to compare area-level socioeconomic differences in outcomes following primary THR surgery for osteoarthritis in England.

This is a population-based prospective cohort study of the National Joint Registry (NJR). Data from the NJR were linked to national mortality, Hospital Episode Statistics and Patient Reported Outcome Measures (PROMs) databases for England from 2007 to 2017 with follow-up to 2023 for outcomes, for patients aged 50 years and over with osteoarthritis. Outcomes of 90-day mortality; 5-year revision rate; 6-month health complications; 1-year rehospitalisation and reoperation for orthopaedic indications; and patient-reported Oxford Hip Score (OHS), post-THR surgery were examined by area-level Index of Multiple Deprivation quintiles. Modified Poisson regression was adjusted for patient age, sex, body mass index, pre-operative physical state and comorbidity.

Among 448,184 patients with primary THR, mean age was 70 years (standard deviation: 9 years) and 61% were women. Patients from the most deprived group were more likely to die within 90 days of the operation compared to the least deprived group (adjusted rate ratio, RR: 1.25 (95% confidence interval (CI) [1.07, 1.46]); adjusted risk difference, RD: 9 (95% CI [2, 16]) per 10,000. Similarly, those from the most deprived group were more likely to experience complications (RR: 1.26 (95% CI [1.21, 1.32]); RD: 1.14% (95% CI [0.92, 1.36])); be rehospitalised (RR: 1.16 (95% CI [1.14, 1.19]; RD: 2.78% (95% CI [2.39, 3.17])) or reoperated (RR: 1.23 (95% CI [1.13, 1.33]); RD: 0.31% (95% CI [0.19, 0.44])) and report poorer OHS (adjusted score: −2.97 (95% CI [−3.10, −2.84]) N = 200,522). There was no variation by deprivation level for THR revision rates at 5 years (RR: 1.02 (95% CI [0.94, 1.10]); RD: 0.02% (95% CI [−0.10, 0.15])). The main study limitations are the lack of complete PROMs data, and the exclusion of self-funded patients or those with private insurance for THR procedures in independent hospitals.

Inequalities in several outcomes after THR are present in England by area-level deprivation. These findings are useful to inform shared decision-making for patients deciding whether to undergo hip replacement and to benchmark the effectiveness of policies which aim to reduce health inequalities following THR.

Reducing health inequalities in the UK National Health Service (NHS) is of national importance.

Total hip replacement (THR) is a commonly used elective surgical procedure.

Few studies report area-level inequalities for a wide range of outcomes following THR, including patient-reported measures, in a national cohort using linked data over a long period.

Using the largest national orthopaedic registry in the world, data for patients who received primary THR surgery over 11 years, were linked to hospital admissions, to examine the socioeconomic differences in a wide range of patient outcomes.

This study found evidence of socioeconomic differences in complications, rehospitalisations and patient-reported wellbeing after surgery, with those from more deprived areas having worse outcomes, these differences were weaker for short-term mortality and reoperations, and not seen for 5-year revision rates.

However, all groups gained equally in terms of patient-reported outcomes albeit from different pre-operative starting points.

These findings are useful measures to inform shared decision-making for patients choosing whether to undergo hip replacement, and to benchmark the effectiveness of policies to reduce inequalities in the care pathways for the provision of THR.

An important limitation of the study is that not all patients had complete information about how they felt before and after surgery. In addition, the experiences of people who paid privately or used private insurance for their hip replacement in non-NHS hospitals were not included.

Rita Patel and colleagues compare area-level socioeconomic differences in multiple outcomes, such as 90-day mortality and 5-year revision rates, among patients aged 50 years and over who underwent primary total hip replacement surgery for osteoarthritis in England.