How does the National Joint Registry's work benefit me? How can I become a part of the NJR's Regional Support network? Who are the working groups the NJR works with? We aim to answer all your questions whether it be in person at a conference, in our Annual Report and weekly reports or here on out website

How the NJR manages your data

How the registry collects patient data

It is mandatory for the following providers of joint replacement surgery to collect and submit data to the registry:

• All NHS trusts and foundation trusts within the jurisdiction of NHS England
• All hospitals within the jurisdiction of NHS Wales
• All hospitals in Northern Ireland performing procedures funded by Health and Social Care Northern Ireland (HSCNI)
• All independent sector hospitals in England and Wales

The number of procedures submitted for each hospital can be seen here, on our StatsOnline service. Performance feedback for hospitals is also included in an NJR Annual Clinical Report, that is provided to chief executives and senior management in NHS trust and health boards and independent healthcare providers. Surgeons are also able to access Annual Clinical Reports for those hospitals in which they practice.

As at 31 March 2021, a total of 3,182,133 hip, knee, ankle, shoulder, and elbow joint procedures had been submitted to the registry. The NJR continues to be the largest orthopaedic registry in the world.

There were 131,603 procedure submissions in 2020/21, a drop of 47.7% on the total reported last year. This is a direct result of many units ceasing elective surgery during the COVID-19 pandemic.

Operation totals

Table 1.1 below shows, the number of procedures reported, by country and joint type, from 1 April 2015 to 31 March 2021. Due to small numbers, data for the Isle of Man and Guernsey are included with the figures for England.

Operation types

Table 1.2 shows the number of procedures reported, by type, from 1 April 2015 to 31 March 2021. Primary procedures make up 91.5% of all procedures reported during 2020/21. The number of ankle, elbow, and shoulder revisions as a proportion of both primaries and revisions is higher than that for hips and knees.

How the NJR manages patient data

The NJR collects data from NHS and independent sector hospitals across England, Wales, Northern Ireland, the Isle of Man and Guernsey. Now with over 4 million records, our data collection and analysis work provides evidence to drive the continuous development and implementation of measures to ensure medical device safety is always top of the agenda. The purpose of our work is to enhance patient outcomes and reduce revision rates year-on-year, to improve standards in quality of care and to address overall cost-effectiveness in joint replacement surgery.

This data collected consists of:

  1. Identifiable data about each patient. We use this to link datasets together, for example, to link a primary and revision operation to analyse outcomes. We don’t collect this data if the patient has declined consent.
  2. Data about the hospital and surgeon. We use this for assurance to make sure that safe and effective care is being delivered.
  3. Data about the medical devices used in the surgery. We use this to monitor whether the medical devices used are safe and effective in the short and long term and to be able to provide the information to enable hospitals to get in touch with patients if there is a subsequent problem with any device type.

The NJR also collects classification data from orthopaedic medical device manufacturers that help us to understand the attributes of the devices used, for example, the type of device, how it is supposed to be used and what materials it is made of.

As well as NJR data, we also combine our datasets with other datasets from NHS Digital. These include Hospital Episode Statistics (HES) that we use to help us understand other health conditions that patients have and how they inform outcomes of surgery, Civil Registration Data and Patients Demographics Service (PDS) data that we use to determine whether patients are still alive and if not when they died and data from the National Patient Recorded Outcome Measures (PROMs) service, which is a national programme that surveys patients on how their health and function are after their surgery.

These datasets are combined by our technology partner (NEC Software Solutions) and then de-identified so that individual patients can’t be identified. The data is then reported using our online reports for hospitals, surgeons, manufacturers and the public. The de-identified datasets are then passed to our statistical analysis contractors (University of Bristol) who use it to enable us to produce our Annual Report, our clinical performance analyses and some of our research publications.

In order to ensure the integrity of our analysis, the data undergoes a cleaning process to remove any records that we think are inaccurate. Some of these exclusions take place at a database level, for example, we remove any records that have not been fully completed before submission by the hospitals, but most exclusions are specific to an individual report or analysis.

You can see how we do this in the following flow diagram sample (from our 2022 NJR Annual Report) that shows how data is cleaned for our annual report and how data flows around the NJR. We are currently reviewing our systems and processes to streamline the way that we capture, analyse and report NJR data to improve accuracy, consistency of reporting and transparency.  

Please click here to see a glossary of terms and abbreviations used in the data flow table below.

how njr data are processed

How NJR data is processed

We are very grateful to all patients who have undergone a joint replacement and have provided their data over the years, which has enabled such a valuable data source. The registry is also appreciative of the work of data entry staff in all participating hospitals, who willingly engage in our stringent data quality award programmes to ensure our information is of high quality, accurate and as complete as is possible.

For further information about NJR Data and how it is collected and processed please click here:

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