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Improving the NJR’s data management processes 


Now with over 3.2 million records, our data collection and analysis work provides evidence to drive the continuous development and implementation of measures to ensure implant safety is always top of the agenda. The purpose of this work is also 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. The NJR collects data from NHS and independent sector hospitals across England, Wales, Northern Ireland, the Isle of Man and the States of Guernsey. 

  1. This data consists of: 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 implants used in the surgery. We use this to monitor whether the implants used are safe and effective in the short and long-term and to be able to provide the information to enable hospitals get in touch with patients if there is a subsequent problem with any implant type.

The NJR also collects classification data from orthopaedic implant manufacturers that helps us to understand the attributes of the implants used, for example the type of implant, 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 also 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 diagrams that shows how data is cleaned for our annual report and how data flows around the NJR. We are currently undertaking further improvement work to streamline the way that we capture, analyse and report NJR data and improve accuracy, consistency of reporting and transparency.  


How NJR data are processed


We are very grateful to all patients who having undergone a joint replacement 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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