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Publication, Part of

Weight Management Services, Quarter 1 to Quarter 4 2022/23 – National Obesity Audit [Management Information]

Other reports and statistics


Appendix A: Data Sources

This is the fourth release of data to form part of the National Obesity Audit (NOA) which now presents data from two sources (hence the slight name change to the publication series). This publication series includes a developing set of nationally agreed measures which will eventually provide a comprehensive picture of activity, access to services and health outcomes of patients using weight management services across England. This allows providers to track, benchmark and improve the quality of these services. Other data sources may be used in future releases. 

A.1 Hospital Episode Statistics (HES)

Hospital Episode Statistics (HES) is a database containing details of all admissions, Accident and Emergency attendances and outpatient appointments at NHS hospitals in England. 

Initially this data is collected during a patient's time at hospital as part of the Commissioning Data Set (CDS). This is submitted to NHS England for processing and is returned to healthcare providers as the Secondary Uses Service (SUS) data set and includes information relating to payment for activity undertaken. It allows hospitals to be paid for the care they deliver.  

This same data can also be processed and used for non-clinical purposes, such as research and planning health services. Because these uses are not to do with direct patient care, they are called 'secondary uses'. This is the HES data set. HES is collected and published monthly as provisional official statistics data with final annual data published at the end of the year as national statistics.  Annual admitted patient care data is available for every financial year from 1989-90 onwards.  

HES data covers: 

  • private patients treated in NHS hospitals (However this data is not included in the NOA) 

  • patients resident outside of England 

  • care delivered by treatment centres (including those in the independent sector) funded by the NHS 

Each HES record contains a wide range of information about an individual patient admitted to an NHS hospital, including: 

  • clinical information about diagnoses and operations 

  • patient information, such as age group, gender and ethnicity 

  • administrative information, such as dates and methods of admission and discharge 

  • geographical information such as where patients are treated and the area where they live 

The Hospital Episode Statistics (HES) webpages provide further information. 

A.2 Population Estimates

Mid-year estimates of the usual resident population for Sub Integrated Care Boards (formerly clinical commissioning groups) in England from the Office for National Statistics have been mapped to Integrated Care Boards (ICBs) and then used to calculate the rates per 100,000 population for the HES dashboard.  

The Midyear population estimates webpages provide further information. 

A.3 Weight Management Services data from the Community Services Data Set (v1.6)

The Community Services Data Set (CSDS) is a patient level, output based, secondary uses data set which aims to collect robust, comprehensive, nationally consistent and comparable person-centred information for children and adults who are in contact with publicly-funded community health services.

CSDS v1.6 is the current version of the data set which went live for local data collection from 1 January 2023. One of the headline changes from the previous version of CSDS was the addition of two new Team Types in Table CYP102 (ServiceType Referred To) to capture specific referrals to children's weight management services (code 55) and adult's weight management services (code 56). This now allows us to start reporting on some initial DQ metrics to support the National Obesity Audit. 

CSDS was developed to help achieve better outcomes and provide data that will be used to commission services in a way that improves health, reduces inequalities, and supports service improvement and clinical quality. This is hoped to be achieved for Weight Management Services as once the data quality in submissions from providers improve,  this will aid further analyses and reporting for the audit.

CSDS data is collected and published monthly as experimenatl statistics. Details of the data collection can be accessed via the CSDS data collection page and all the monthly publications can be accessed via the CSDS publication series webpage


Appendix B: HES Technical Notes

England total and provider level breakdown includes data for persons not resident in England, or of no fixed abode/ unknown residence. All other sub-national breakdowns include data only for patients resident in England.  

B.1 Coding for bariatric surgery

The term ‘bariatric surgery’ is often used to define a group of procedures that can be performed to facilitate weight loss although these procedures can be performed for conditions other than weight loss. We have used primary diagnosis of obesity using the tenth revision of the International Classification of diseases (ICD10 code E66), to limit the bariatric procedures to those related to obesity. There is a small possibility that people undergoing bariatric surgical procedures for cancer may be counted. 

Here is a list of the OPCS codes (Office for Population, Censuses and Surveys: Classification of Intervention and Procedures, 4th Revision (OPCS4)) used for each type of procedure where we counted each patient where there has been at least one instance of each type of procedure. For revisions, in some cases evidence of previous bariatric procedure in the preceding 10 financial years has also been looked at. 

Primary procedure: G281, G282, G283, G284, G285, G301, G302, G303, G304, G312, G321, G331, G716. 

Revision procedure: G305, G315, G316, G322, G323, G324, G325, G332, G387, G717 

Gastric balloons and bubbles: G481, G485. 

Further details are in the metadata. 

B.2 Coding for diagnoses of severe mental illness

ICD10 code list used for diagnoses of severe mental illness:

F068, F105, F200, F201, F202, F203, F204, F205, F206, F208, F209, F21X , F220, F228, F229, F230, F231, F232, F233, F239, F24X, F250, F251, F252, F259, F29X, F300, F302, F308, F309, F310, F311, F312, F313, F314, F315, F316, F317, F318, F319, F323, F333, F39X, F442, F449, F452, F527, F531, F688

B.3 HES Disclosure control

Disclosure control has been applied to minimise the risk of patient identification.  


National level data 

No disclosure control for small numbers.  

Breakdowns below national level 

The following steps have been applied to reduce the risk of identifying individuals from small numbers. 

1) If the national total is between 1 and 7 (inclusive), no sub-national breakdown will be displayed. 

2) If the national total is greater than or equal to 8 

  • Sub-national counts between 1 and 7 (inclusive) will be displayed as ’*’.  

  • For the under 18 and over 75 years age groups no sub national breakdowns have been included. 

  • Zeroes will be unchanged. 

  • All other counts will be rounded to the nearest 5. 


National level data 

No disclosure control required for small numerator or denominator.  

Breakdowns below national level 

The following should be applied when calculating percentages at sub-national level: 

1) Where the numerator or denominator is between 1 and 7 (inclusive), no percentage or rate is calculated, and a ’*’ will be displayed. 

2) Where the numerator is zero, the percentage will be 0%. 

3) Where the unrounded numerator and denominator are greater than or equal to 8, a percentage or rate is calculated using the rounded numerator or denominator. 

B.4 Numerator/Denominator

Numerators and denominators are the 2 numbers that make up a fraction. The numerator is the number that sits at the top. It represents how many equal parts of the whole are present. The denominator is the number at the bottom. It tells us how many equal parts the whole is divided into. 

Appendix C: CSDS Technical Notes

National and provider level breakdowns include data for providers in scope of Tier 2 and 3 weight management services, though not all providers in scope are currently included in the published data. 

C.1 Coding for Body Mass Index (BMI) metrics

The recording of BMI has been gathered in multiple formats.

Submission to CYP202CareActivity:

  • SNOMED codes indicating a BMI status
  • SNOMED codes indicating a BMI value recorded
  • SNOMED codes indicating height or weight
  • An observational value and unit 

Submission to CYP611Obs:

  • Weight, height or length values submitted to CYP611Obvs

Please refer to the "BMI Codes List" tab of the metadata for the full list of accepted clinical codes (SNOMED and READ).

C.2 CSDS Disclosure Control

Disclosure control has been applied to minimise the risk of patient identification.  


All levels of aggregation are subject to disclosure control. This includes national level totals.  

Counts between 1 and 7 (inclusive) should be rounded to the nearest 5.  

All other counts above 7 will be rounded to the nearest 5.

Zeroes will be unchanged.


Percentages will be calculated based on rounded numerators and rounded denominators, and displayed to 1 decimal place.

Other Aggregations

Averages will be calculated based on unrounded numerators and unrounded denominators.

Appendix D: Further information

Comments on this report would be welcomed. Any questions concerning any data in this publication, or requests for further information, should be addressed to:  

Telephone: 0300 303 5678 

Email: [email protected]  
Press enquiries should be made to: 

Media Relations Manager 

Telephone: 0300 303 5678 

Email: [email protected]  

You may also feedback your comments on this release by using our feedback form:


Published by NHS England, part of the Government Statistical Service 

© 2023 NHS England

  This work may be re-used by NHS and government organisations without permission. 

Last edited: 13 July 2023 8:52 am