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The Effect of Age, Sex, Area Deprivation, and Living Arrangements on Total Knee Replacement Outcomes: A Study Involving the United Kingdom National Joint Registry Dataset

Edwards, Hannah, B., BA, MA, MSc(Lond)1,2,a; Smith, Michèle, BSc, MSc, PhD, PGCE1,b; Herrett, Emily, BSc, MSc, PhD3,c; MacGregor, Alexander, MA, MSc, MBBS, MD, PhD, FRCP4,d; Blom, Ashley, MBChB(CapeT), FRCS1,5,e; Ben-Shlomo, Yoav, MB, BS, MSc(Lond), PhD, MRCP1,2,fon behalf of the National Joint Registry for England, Wales, Northern Ireland, and the Isle of Man

doi: 10.2106/JBJS.OA.17.00042
Scientific Articles: PDF Only

Background: Total knee replacement (TKR) is a common procedure for the treatment of osteoarthritis that provides a substantial reduction of knee pain and improved function in most patients. We investigated whether sociodemographic factors could explain variations in the benefit resulting from TKR.

Methods: Data were collected from 3 sources: the National Joint Registry for England, Wales, Northern Ireland, and the Isle of Man; National Health Service (NHS) England Patient Reported Outcome Measures; and Hospital Episode Statistics. These 3 sources were linked for analysis. Pain and function of the knee were measured with use of the Oxford Knee Score (OKS). The risk factors of interest were age group, sex, deprivation, and social support. The outcomes of interest were sociodemographic differences in preoperative scores, 6-month postoperative scores, and change in scores.

Results: Ninety-one thousand nine hundred and thirty-six adults underwent primary TKR for the treatment of osteoarthritis in an NHS England unit from 2009 to 2012. Sixty-six thousand seven hundred and sixty-nine of those patients had complete knee score data and were included in the analyses for the present study. The preoperative knee scores were worst in female patients, younger patients, and patients from deprived areas. At 6 months postoperatively, the mean knee score had improved by 15.2 points. There were small sociodemographic differences in the benefit of surgery, with greater area deprivation (−0.71 per quintile of increase in deprivation; 95% confidence interval [CI], −0.76 to −0.66; p < 0.001) and younger age group (−3.51 for ≤50 years compared with 66 to 75 years; 95% CI, −4.00 to −3.02; p < 0.001) associated with less benefit. Cumulatively, sociodemographic factors explained <1% of the total variability in improvement.

Conclusions: Sociodemographic factors have a small influence on the benefit resulting from TKR. However, as they are associated with the clinical threshold at which the procedure is performed, they do affect the eventual outcomes of TKR.

Level of Evidence: Prognostic Level IV. See Instructions for Authors for a complete description of evidence.

This is an open access article distributed under the Creative Commons Attribution License 4.0 (CCBY), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

1University of Bristol, Bristol, United Kingdom

2NIHR Collaboration for Leadership in Applied Health Research and Care West, Bristol, United Kingdom

3London School of Hygiene and Tropical Medicine, London, United Kingdom

4University of East Anglia, Norwich, United Kingdom

5North Bristol National Health Service Trust, Bristol, United Kingdom

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Investigation performed at the University of Bristol, Bristol, United Kingdom

Disclosure: This research was supported by the National Institute for Health Research (NIHR) Collaboration for Leadership in Applied Health Research and Care (CLAHRC) West at University Hospitals Bristol NHS Foundation Trust. Ms. Edwards is funded by the CLAHRC West, and Dr. Ben-Shlomo is partially funded by the CLAHRC West and is Lead for the group’s Equity, Appropriateness and Sustainability Theme. The funder had no role in the design, analysis or interpretation of the study. The University of Bristol receives clinical trial research funding from Stryker. On the Disclosure of Potential Conflicts of Interest forms, which are provided with the online version of the article, one or more of the authors checked “yes” to indicate that the author had other relationships or activities that could be perceived to influence, or have the potential to influence, what was written in this work (

© 2018 The Authors. Published by Wolters Kluwer Health, Inc. on behalf of The Journal of Bone and Joint Surgery, Incorporated.