Annual progress: Data completeness and quality

There are three types of organisations in England carrying out hip, knee, ankle, elbow, and shoulder joint replacement surgery.

• NHS hospitals
• Independent sector hospitals
• Independent sector treatment centres (ISTC)

There are no ISTCs in either Wales or Northern Ireland.  Northern Ireland is shown separately the Table below as the number of reported procedures, although increasing, remains low.  Northern Ireland started to submit data to the NJR in February 2013.

Table 1.3 shows the proportion of procedures by type of provider.

By 31 March 2014, 1,658,308 hip, knee, ankle, shoulder and elbow replacement procedures had been submitted to the NJR.  There were 205,686 procedures submitted in 2013/14 – the highest number of submissions in any year since the registry began.

Operation totals

The table below shows, by country and joint type, the numbers of procedures recorded on the NJR for the financial years from 2009/10 to 2013/14.  As for the previous five years, the number of knee replacement procedures (100,059) exceeded the number of hip replacement procedures (99,190) in 2013/14 (50.2% and 49.8% as a proportion).

The table below shows the number of procedures reported by type from 1 April 2009 to 31 March 2014.  Primary procedures make up 91.3% of all procedures reported during 2013/14, whilst the proportion of revisions has decreased to 8.6% from 9.4% in 2012/13.

The linkability rate for 2013/14 was 95.1%, a slight decrease from 2012/13

The linkability rate compares the number of records submitted with the patient’s NHS number with the number of procedures recorded in the NJR.  The NHS number is required to link all primary and revision procedures relating to a single patient (NJR data is submitted for NHS number tracing and the ‘linkability’ figure includes NHS numbers that were traced subsequent to the operation details being submitted to the NJR). 

The ability to link all operations relating to a single patient is vital in determining clinical outcomes and, without a high NHS number submission rate, the NJR’s ability to monitor clinical and implant performance is adversely affected.

Where the NHS number is missing, tracing is attempted using the NHS Demographics Batch Service.  This does, however, require the patient’s name, date of birth and postcode being correctly submitted. 

The consent rate for 2013/14 was 91.8%, a slight increase from 2012/13

The consent rate compares the number of records submitted where the patient has agreed to their personal data (see note 3) being stored on the NJR database with the number of procedures recorded on the NJR.  It is a requirement in England, Wales and Northern Ireland that patients give voluntary consent to have their personal data held on the NJR with their operation data. This personal information is essential to link patients’ primary and revision procedures together in order to monitor the outcomes of joint replacement surgery. Without high rates of consent, the NJR cannot achieve its goals.

Patients rarely decline consent and many units achieve consent rates of 100%. Lower consent rates in other units are generally caused by a lack of robust processes which mean that the completed consent form is not available to the person submitting the procedure details to the NJR.

Note 3: Personal data includes NHS number, surname, date of birth and postcode.

The compliance rate measures the number of submissions to the NJR and compares it to the number of levy returns for the numbers of implants sold (notes 1, 2). It is not possible to establish a direct link between a single levy and the use of the implant and, therefore, this measurement is subject to variations caused by such factors as the procurement cycle, the amount of stock purchased in a single year, and how that stock is used.  In some periods, there will be a greater number of procedures reported than levies collected leading to a positive (>100%) compliance rate.

About the key indicators of data quality and completeness

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

• all NHS Trusts and Foundation Trusts within NHS England
• all NHS Wales hospitals
• all NHS-funded procedures in Northern Ireland
• all independent sector hospitals in England and Wales

Performance against the three key indicators of data quality (compliance, consent and linkability) has continued to improve generally, although a high degree of monitoring and support to orthopaedic units is still required.  

Unit-level performance against these key indicators are provided in Part Four of the report and this information can be found here or in the PDF downloads column on the right hand side of the page. 

This data is also provided through the NJR StatsOnline service, and in a standard annual clinical report provided to Trust and Health Board chief executives and independent healthcare companies.