Trust, Local Health Board and unit-level activity and outcomes

The observed numbers of revisions of hip and knee replacements for each hospital were compared to the numbers expected, given the unit’s case-mix in respect of age, gender and reason for primary surgery. Hospitals with a much higher than expected revision rate for hip and knee replacement have been identified. These hospitals had a revision rate that was above the upper of the 99.8% control limits (these limits approximate to +/-3 standard deviations). We would expect 0.2% (i.e. one in 500) to lie outside the control limits by chance, with approximately half of these (one in 1,000) to be above the upper limit.

When examined over the past ten years of the registry, a total of 34 hospitals reported higher than expected rates of revision for knee replacement, and 23 hospitals had higher than expected rates of revision for hip surgery. However, revisions taken only from the last five years of the registry showed only 13 hospitals reporting higher than expected rates for knees, and 11 for hips.

The 90-day mortality rate for primary hip and knee replacement was calculated using the last five years of data for all hospitals by plotting standardised mortality ratios for each hospital against the expected number of deaths. No hospitals had higher than expected mortality rates for either hip or knee replacement.

Note: The case mix for mortality includes age, gender and ASA grade. Trauma cases have been excluded from both the hip and knee mortality analyses together with hips implanted for failed hemi-arthroplasty or for metastatic cancer (the latter only from November 2014 when recording of this reason began). Also, where both left and right side joints were implanted on the same day, only one side was included in the analysis.

Note: Any units identified as potential outliers here have been notified. All units are provided with an NJR Annual Clinical Report and additionally have access to the online NJR Management Feedback system.

Important note about the outlier hospitals listed

In earlier annual reports, we reported outlying hospitals based on all cases submitted to the registry since 1 April 2003. To reflect changes in hospital practices and component use, we now report outlying hospitals based on the last ten years (13 February 2011 to 13 February 2021) and five years of data (13 February 2016 to 13 February 2021 inclusive, the latter date being when the dataset was cut). These cuts of data exclude the majority of withdrawn outlier implants and metal-on-metal total hip replacements from analysis, and thus better represent contemporary practice.

Table 4.5 Outliers for hip mortality rates since 2016².
  None identified

Table 4.6 Outliers for knee mortality rates since 2016².
  None identified

Table 4.7 Outliers for hip revision rates, all linked primaries from 2011¹.
  BMI Clementine Churchill Hospital (Middlesex)
  BMI The Meriden Hospital (West Midlands)
  Bradford Royal Infirmary
  Broadgreen Hospital
  Chorley and South Ribble Hospital
  Colchester General Hospital
  Fitzwilliam Hospital (Cambridgeshire)
  Homerton University Hospital
  Hospital of St Cross
  Milton Keynes Hospital
  North Downs Hospital (Surrey)
  Nuffield Orthopaedic Centre
  Orthopaedics and Spine Specialist Hospital (Cambridgeshire)
  Salisbury District Hospital
  South Tyneside District Hospital
  Southampton General Hospital
  Spire Hartswood Hospital (Essex)
  St Richard's Hospital
  Sussex Orthopaedic NHS Treatment Centre
  The Tunbridge Wells Hospital
  Wansbeck Hospital
  Watford General Hospital
  Weston General Hospital

Table 4.8 Outliers for hip revision rates, all linked primaries from 2016².
  Castle Hill Hospital
  Clifton Park Hospital (North Yorkshire)
  Darent Valley
  Fulwood Hall Hospital (Lancashire)
  Hexham General Hospital
  Milton Keynes Hospital
  North Tyneside General Hospital
  Nuffield Orthopaedic Centre
  Southampton General Hospital
  Wansbeck Hospital
  Weston General Hospital

Table 4.9 Outliers for knee revision rates, all linked primaries from 2011¹.
  Abergele Hospital
  Ashford Hospital
  BMI Bishops Wood Hospital (Middlesex)
  BMI Goring Hall Hospital (West Sussex)
  BMI The London Independent Hospital (Greater London)
  BMI The Meriden Hospital (West Midlands)
  Broadgreen Hospital
  County Hospital Louth
  Ealing Hospital
  Guy's Hospital
  Heatherwood Hospital
  Hillingdon Hospital
  Hinchingbrooke Hospital
  King Edward VII’s Hospital Sister Agnes (Greater London)
  Mount Vernon Treatment Centre
  Nevill Hall Hospital
  Nuffield Health Chichester Hospital (West Sussex)
  Nuffield Orthopaedic Centre
  Orthopaedics and Spine Specialist Hospital (Cambridgeshire)
  Peterborough City Hospital
  Queen Elizabeth The Queen Mother Hospital
  Southampton General Hospital
  Southmead Hospital
  Spire Hull and East Riding Hospital (East Yorkshire)
  Spire Southampton Hospital (Hampshire)
  Springfield Hospital (Essex)
  St Mary's Hospital (Isle of Wight)
  St Richard's Hospital
  Sussex Orthopaedic NHS Treatment Centre
  The Royal National Orthopaedic Hospital (Stanmore)
  Torbay Hospital
  University College Hospital
  University Hospital Llandough
  York Hospital

Table 4.10 Outliers for knee revision rates, all linked primaries from 2016².
  BMI Bath Clinic (Avon)
  BMI The South Cheshire Private Hospital (Cheshire)
  Guy's Hospital
  Hillingdon Hospital
  King Edward VII’s Hospital Sister Agnes (Greater London)
  Practice Plus Group Hospital - Barlborough (Derbyshire)
  Nuffield Orthopaedic Centre
  Queen Elizabeth The Queen Mother Hospital
  Southmead Hospital
  Spire Bushey Hospital (Hertfordshire)
  Springfield Hospital (Essex)
  The Royal National Orthopaedic Hospital (Stanmore)
  Yeovil District Hospital

Better than expected performance

This year we have again listed hospitals where revision rates are statistically better than expected. The lists here show units that lie below the 99.8% control limit which also achieved greater than 90% compliance across all of the NJR data quality audits. Units with lower data quality compliance are automatically excluded from these lists.

Table 4.11 Better than expected hip revision rates, all linked primaries from 2011¹.
  Calderdale Royal Hospital
  Ipswich Hospital
  Musgrave Park Hospital
  Royal Derby Hospital
  Royal Devon and Exeter Hospital (Wonford)
  Royal Surrey County Hospital
  Sunderland Royal Hospital

Table 4.12 Better than expected hip revision rates, all linked primaries from 2016².
  Calderdale Royal Hospital
  Musgrave Park Hospital
  Ulster Independent Clinic (Belfast)

Table 4.13 Better than expected knee revision rates, all linked primaries from 2011¹.
  Bishop Auckland Hospital
  Burnley General Hospital
  Claremont Hospital (South Yorkshire)
  Craigavon Area Hospital
  Hexham General Hospital
  Ipswich Hospital
  Musgrave Park Hospital
  Norfolk and Norwich Hospital
  North Tyneside General Hospital
  Nottingham Woodthorpe Hospital (Nottinghamshire)
  Nuffield Health Cambridge Hospital (Cambridgeshire)
  Nuffield Health Derby Hospital (Derbyshire)
  Nuffield Health Ipswich Hospital (Suffolk)
  Princess Alexandra Hospital
  Spire Norwich Hospital (Norfolk)
  Stepping Hill Hospital
  The Elective Orthopaedic Centre

Table 4.14 Better than expected knee revision rates, all linked primaries from 2016².
  Ipswich Hospital
  Musgrave Park Hospital
  Nottingham Woodthorpe Hospital (Nottinghamshire)

Note: ¹ Date range 13 February 2011 to 13 February 2021 inclusive. ² Date range 13 February 2016 to 13 February 2021 inclusive.

Overall in 2020, 141 NHS trusts and local health boards (comprising 256 separate hospitals) and 177 independent hospitals were open and eligible to report patient procedures to the registry. Data were not submitted in 2020 by five NHS hospitals (including two trauma units) and two independent hospitals. Due to the COVID-19 pandemic, hospitals were directed at the end of March 2020 to cease inputting records to audits and to divert staff to higher priority tasks, therefore a number of elective procedures were not initially reported as data entry activity wasn’t then resumed until July that year. It is expected that these procedures will be identified by units and entered retrospectively or submitted as part of our ongoing audit programme.

Compliance is measured by comparing the proportion of all joint replacements entered into the registry, with those submitted to the Hospital Episodes Statistics (HES) and Patient Episode Database Wales (PEDW) services. These data rely on submissions by hospitals and are only available by NHS trust. No data are currently available from private providers and figures also exclude units in Northern Ireland as compliance data are not available.

• 37% of NHS hospitals in England and Wales reported 95% or more of the joint replacements they undertook
• 37% reported between 80% to 95%
• 26% reported less than 80%

Of those hospitals submitting data, the proportion of patients who gave permission (consent) for their details to be entered into the registry were:

NHS hospitals
• 33% of NHS hospitals achieved a consent rate of greater than 95%
• 36% achieved a consent rate of 80% to 95%
• 31% recorded a consent rate of less than 80%

Independent hospitals
• 57% of independent hospitals achieved a consent rate greater than 95%
• 30% achieved a consent rate of 80% to 95%
• 13% recorded a consent rate of less than 80%

There has been a decrease in recorded consent for all submitting units when compared to the previous year, with those achieving a higher than 95% rate falling to 43% from 56% in 2019. The proportion of all units achieving a higher than 80% consent rate, has increased slightly. This reduction in consent rate can be related to the ratio of elective to trauma cases, which changed significantly during 2020, having a higher proportion of trauma cases compared to previous years. There was a significant reduction in elective cases due to COVID-19 and trauma cases have a higher rate where NJR consent is not obtained.

Similarly, the proportion of entries in which there is significant data to enable the patient to be linked to an NHS number (linkability) is listed.

NHS hospitals
• 81% achieved a proportion of patients with a linkable NHS number greater than 95%
• 17% achieved a proportion of 80% to 95%
• 2% recorded a proportion of less than 80%

Independent hospitals
• 68% achieved a proportion of patients with a linkable NHS number greater than 95%
• 25% achieved a proportion of 80% to 95%
• 7% recorded a proportion of less than 80%

There has been a drop in linkability from 2019, with the percentage of submitting units achieving over 95% in 2020 falling from 80% to 76%. The proportion achieving a greater than 80% linkability rate has increased slightly to 20% compared with 17% in 2019.  The drop in linkability is related to the fall in consent rate.

Note: Independent hospitals might be expected to have lower linkability rates than NHS hospitals, as a proportion of their patients may come from overseas and do not have an NHS number.

Performance and data entry quality indicators are shown here for trusts and local health boards (many of whom comprise more than one hospital) and independent (private) providers in England, Wales, Northern Ireland, the Isle of Man and States of Guernsey for the 2020 calendar year. Outcomes analysis after hip and knee replacement surgery is also provided for the period 2011 to 2021.

The full analysis for units can be found in the document available in the downloads section.