INTRODUCTION

The United Kingdom National Bariatric Surgery Registry Publication of Hospital and Surgeon-level data for bariatric surgery in England

Summary

The National Bariatric Surgical Registry (NBSR) Committee on behalf of the British Obesity and Metabolic Specialist Society (BOMSS) and in collaboration with Dendrite Clinical Systems presents the outcomes data for patients undergoing bariatric surgery in England for the financial years from 2023-2025 on https://nbsr.e-dendrite.com.

In addition the British Obesity and Metabolic Specialist Society has updated their Professional Standards and Commissioning Guidance. A summary of this document is available on the BOMSS website and should be read in conjunction with this report.

Background

The National Bariatric Surgical Registry was originally set up a voluntary audit tool to monitor activity and outcomes of bariatric surgery in the UK.

Since 2013 data entry for all NHS bariatric cases has been mandated; and following a call for a culture of openness, transparency and candour from the Francis Report the NBSR had been publishing a yearly update of Consultant- level Outcome Publication (COP) report of the NHS bariatric activity in England.

Due to the COVID pandemic there was an interruption in annual reporting and in order to re-establish our annual cycle we are presenting two years’ worth of analysis (ie from April 2023- March 2025).

Clinical activity

In alignment with the NICE guidance, submission of peri-operative data for all bariatric cases to the NBSR has been, and remains a mandatory requirement for both NHS and private cases. In addition private sector data is already in the public domain through the Patient Health Information Network (PHIN) website as per their Parliamentary mandate.

Hence this year for the first time we have included the total activity (ie NHS, insurance and self- funded) of bariatric surgery recorded in the Registry for each contributing surgeon (as opposed to NHS activity alone).

In line with previous reports we have reported activity over the last over the last four years as we use this as our definition of “current activity” and as a denominator to benchmark clinical outcomes. It should be noted that some surgeons may have contributed to the NBSR for only part of the four year period because they have been newly appointed consultants, or have only recently started undertaking bariatric surgery.

Interpretation of Surgical Volume data

Both the International Federation of Surgical Obesity and BOMSS have consistently recognised that surgical volume is a critical pre-requisite of a high quality bariatric surgical service.

BOMSS has recently reviewed and updated their guidance and recommend:

• Surgeons undertaking independent primary NHS bariatric surgery should have performed a minimum of 160 procedures (i.e. 40 cases per annum) over the previous four years
• Surgeons undertaking independent revisional surgery should have performed a minimum of 240 procedures (i.e. 60 cases per annum) over the previous four years

Summary of NHS activity

The NHS bariatric activity for each financial year are summarised in the tables below based on a data cut taken from the NBSR database on the 9th January 2026.

As before, this data summarises all NHS funded primary and revisional bariatric surgery.

This summary does NOT include the following:

• Patients who had surgery outside England
• Patients who had temporary weight loss interventions (eg gastric balloons)
• Patients who had elective surgery to treat long term complications associated with bariatric surgery (eg gallstones)

SUMMARY OF PUBLISHED NHS CONSULTANT OUTCOME DATA

In line with previous presentations we have summarised the NHS bariatric surgical activity recorded by individual consultants for the following variables:

• Total number of operations, broken down by common procedures. For this cycle we have chosen not to separately list gastric band procedures due to the very small number of procedures performed. We have also grouped together Roux en Y and One Anastomosis Gastric Bypasses under the umbrella term “gastric bypass”
• Reporting of revisional surgery rates expressed as percentage of workload of each surgeon
• Clinical and demographic details of patients undergoing surgery
• Length of hospital stay
• In-hospital mortality

OUTLIERS

As per our previous mandate from the Department of Health, and in accordance with other HQIP quality accounts, the NBSR Committee has reviewed outcome measures to identify negative outliers i.e. hospitals and surgeons whose performance in specific areas appear to fall below the expected standards.

In line with previous reports we have undertaken exercises to identify:

• Clinical Outcome outliers – i.e. surgeons and hospitals whose clinical outcomes as recorded on the Registry falls below the expected standard and
• Data outliers- i.e. institutions and surgeons whose quality of data entry into the Registry falls below the expected standard

CLINICAL OUTCOMES OUTLIERS

In line with previous reports we have used in-hospital mortality rates as our clinical outcome measure. The definition of an “in-hospital death” used by NBSR is a death that occurs during the initial hospital stay before discharge.

Over the two year period between April 2023 and March 2025, a total of three NHS in-hospital deaths following primary bariatric surgery were recorded by the NBSR database representing an overall mortality rate of 0.04%.

In terms of outlier policy, the data for any surgeon or hospital who recorded any NHS in-hospital death following primary bariatric surgery during the two year analysis period were flagged.

The totality of their practice (including all revisional cases and private cases) was then re-analysed over the preceding four year period (April 2021 - March 2025).

In terms of our hospital outlier policy:

• Any hospital with an overall in-hospital mortality rate of above 0.5% over the preceding four year period was deemed an outlier

• Any surgeon with a single NHS in-hospital death following primary bariatric surgery; and an overall in-hospital mortality rate of above 0.5% over the preceding four year period triggered an alert status.
• Any surgeon with two or more NHS in-hospital deaths following primary bariatric surgery; and a mortality rate of above 0.5% over the preceding four year period was deemed to be an outlier.

Interpretation of Clinical Outlier Data

During this four year cycle no hospital or surgeon was noted to be an outlier in terms of overall in-hospital mortality rate.

One surgeon was noted to have triggered an alert status in terms of in-hospital mortality rate.

The NBSR committee has no further role other than highlighting this figure. We appreciate that a single death may be a statistical quirk and may already have been investigated locally. However in the interests of transparency we have published this data and informed the surgeon and his Responsible Officer.

We note that our mortality analysis currently excludes patients who were discharged from hospital but are then readmitted and die within 90 days of surgery. Previous analysis of the Hospital Episode Statistics (HES) has shown a reassuringly low rate of 90 day mortalities. Nonetheless to address this potential lacuna we will be including as part of our analysis in the next Consultant Outcome Publication all NHS and private sector mortalities recorded within a 90 day period of any index primary bariatric procedure between April 2025 and March 2026.

DATA QUALITY ASSESSMENT

NHS HOSPITAL DATA OUTLIERS

This year as part of our data quality assurance exercise for hospital entry we analysed the number of duplicate procedures added in error to the NBSR database by each institution.

The presence of duplicates has implications in terms of accurate ascertainment of surgical volume and hence benchmarking of outcomes, and is therefore an important marker of data quality.

In terms of our analysis of duplicate records, we firstly excluded all hospitals which recorded less than 10 bariatric cases over the four year period.

Of the 46 NHS Trusts submitting more than 10 cases, the median rate of duplicates records was 0%, with 24 Trusts having no duplicate records.

As part of our outlier analysis we then excluded hospitals where the total number of duplicate records was less than 10.

We then identified the following Trusts as negative outliers with 10 or more duplicate records and an overall duplicate record rate of over 2%.

• Ashford & St Peters Hospital, Chertsey
• Homerton University Hospital, London
• Huddersfield Royal Infirmary
• Luton & Dunstable University Hospital
• Royal Berkshire Hospital, Reading
• Royal Derby Hospital
• Royal Shrewsbury Hospital
• St George's Hospital, London
• University Hospital, Lewisham

NHS CONSULTANT DATA OUTLIERS

In line with previous reports we analysed the initial operations record for each surgeon to assess data completion for each patient record. A simplified funnel plot was then used to identify surgeons whose the degree of data completion was outside the confidence limits.
In terms of surgeon outliers, although ultimate responsibility for data entry remains with the surgeon, NBSR remains of the view that optimum data entry is achieved through a collaborative process involving the Trust and all the clinicians involved in the multidisciplinary team.

ACKNOWLEDGEMENT OF SUPPORTING TRUSTS

The NBSR committee would like to acknowledge voluntary financial contributions from Hospital Trust towards production of this report and maintenance of the NBSR.

CERTIFICATION

We believe the 4-year data for 2021-2025 are a correct representation as recorded on the Registry of the overall volume of NHS and private sector bariatric surgical activity; and NHS data in terms of baseline BMI, degree of baseline obesity-related disease, type of operation, in-hospital mortality, and length of hospital stay.