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Publication, Part of

Provisional Patient Reported Outcome Measures (PROMs) in England - or Hip and Knee Replacement Procedures (April 2020 to March 2021)

Official statistics



From April 2009 onwards, patients undergoing elective inpatient surgical procedures for hip replacement and knee replacement have been invited to complete pre- and post-operative questionnaires on their general and condition-specific health. Patient participation in PROMs is on a voluntary basis.

Responses to these questionnaires are analysed to assess the outcomes of the surgical procedures based on patients’ self-reported health.

PROMs publications and data can be used by patients to inform their choice of hospital provider and are used to by hospital clinicians to inform decisions about individual patients’ direct care. The data have also been used in medical research studies to improve outcomes by comparing scores across different types of treatments.

In order to respond to the challenges posed by the coronavirus pandemic NHS hospitals in England were instructed to suspend all non-urgent elective surgery for patients for parts of the 2020/21 reporting period. This has directly impacted upon reported volumes of activity pertaining to Hip & Knee replacements reported in PROMS. In addition it is possible that behaviours around activities relating to the completion, return and processing of pre and post-operative questionnaires may have also been impacted when compared to earlier years data where behaviours and processes related to managing the current pandemic were not in place.


Analysis in this report is based on provisional data for:

  • Pre-operative patient questionnaires completed between 1 April 2020 and 31 March 2021 and any associated in-patient hospital episodes and post-operative questionnaires;
  • Episodes of inpatient hospital care where the episode started between 1 April 2020 and 31 March 2021 and included a PROMs-eligible surgical procedure (hip or knee replacement) and any associated pre- and post-operative questionnaires. A small number of episodes recorded more than one eligible procedure; each procedure is treated independently for purposes of analysis. 
  • The data source of these episodes is the Hospital Episode Statistics data warehouse (‘HES’) , where possible, PROMs questionnaires have been linked to records of hospital inpatient activity in order to deliver a richer dataset for analysis and to provide key variables necessary for casemix adjustment.

Patient Questionnaires and Measures

Condition-specific measures

Patients receiving hip or knee replacements are asked to complete questions that are specifically tailored to their condition:

  • The Oxford Hip Score (OHS) 
  • The Oxford Knee Score (OKS) 
General health measures

All patients are also asked to complete two general measures, the EQ-5DTM Index and the EQ VAS, both before and after their surgery:

EQ-5DTM Index is a five item measure that asks patients about their:

  • ability to pursue their usual activities;
  • current experience of anxiety and/or depression, if any;
  • current experience of pain and discomfort, if any; 
  • mobility, and;
  • ability to wash and dress themselves (self-care). 

EQ – Visual Analogue Scale (EQ VAS) is a single-item ‘thermometer’-style measure which asks patients to rate their general health at the time of completion on a linear scale from 0 to 100, with 100 representing the best possible state of health.

Within their post-operative questionnaires, all patients are also asked:

  • how they would describe the results of their operation (satisfaction), and; 
  • how their problems are now, compared with before the operation (success).

Documents included in this publication

This publication includes:

  • Data Quality Tables
  • Interactive Score Comparison Tool
  • CSV Data Pack (with footnotes)
  • Interactive PowerBi report

Modelled Records

PROMs scores are adjusted using statistical models which account for the fact that each provider organisation deals with patients of differing complexity or casemix. Some hospitals may treat older, sicker patients and others may be specialist centres that can take patients with more complex conditions than can be treated at a general hospital. 

Casemix adjustment allows for fair comparison between providers and England as a whole. In effect it estimates the score an organisation would have if it treated a population with the same complexity as the national average.

In order for the casemix adjustment to be calculated, certain criteria must be met. Where this criteria is met, the record is called a “modelled record”. The pre-operative and post-operative questionnaire must link together and be complete. They must also be linked to an episode from the HES data set as well as having some complete fields (e.g. IMD) for the episode. More information about the casemix adjustment can be found in the PROMs Methodology document .

Further Information

PROMs Guide

For more details on the background to the PROMs programme and an overview of data collection, processing, scoring and linking, refer to A guide to PROMs Methodology.

Data Quality

Important information about the quality of the data from which these statistics are derived is set out in the accompanying Data Quality Statement and the Data Quality Tables.

Hospital Episode Statistics

Learn more about Hospital Episode Statistics, and to access the many published analyses and datasets.


Any and all copyrights in the EQ 5D™ questions, their order, layout and images vest in the EuroQol Group. The EuroQol Group reserves all rights. © 1992 EuroQol Group. EQ 5D™ is a trademark of the EuroQol Group.

Any and all copyrights in the Oxford Hip Score and Oxford Knee Score questions, their order and layout vest in Oxford University Innovation Limited, previously Isis Innovation Limited. Oxford University Innovation Limited reserves all rights. 

Except where expressly stated to the contrary, the Department of Health PROMs questionnaires are protected by Crown copyright. © Crown Copyright 2008–2011.

Last edited: 18 July 2023 3:53 pm