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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

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Data Quality Statement


This data quality statement aims to provide users with an evidence based assessment of quality of the statistical output included in this publication.  

It reports against those of the nine European Statistical System (ESS) quality dimensions and principles appropriate to this output. The original quality dimensions are: relevance, accuracy and reliability, timeliness and punctuality, accessibility and clarity, and coherence and comparability; these are set out in Eurostat Statistical Law. However more recent quality guidance from Eurostat includes some additional quality principles on: output quality trade-offs, user needs and perceptions, performance cost and respondent burden, and confidentiality, transparency and security. 

In doing so, this meets NHS England's obligation to comply with the UK Statistics Authority (UKSA) code of practice for statistics and the following principles in particular: 

  • Trustworthiness pillar, principle 6 (Data governance) which states “Organisations should look after people’s information securely and manage data in ways that are consistent with relevant legislation and serve the public good.” 

  • Quality pillar, principle 3 (Assured Quality) which states “Producers of statistics and data should explain clearly how they assure themselves that statistics and data are accurate, reliable, coherent and timely.” 

  • Value pillar, principle 1 (Relevance to Users) which states “Users of statistics and data should be at the centre of statistical production; their needs should be understood, their views sought and acted upon, and their use of statistics supported.” 

  • Value pillar, principle 2 (Accessibility) which states “Statistics and data should be equally available to all, not given to some people before others. They should be published at a sufficient level of detail and remain publicly available.” 


This dimension covers the degree to which the statistical product meets user needs in both coverage and content. 

This publication is considered to be of particular interest to NHS and independent sector providers in England and to NHS commissioning organisations. However, data and findings are likely to be of interest to a much broader base of users. 

Accuracy and reliability

This dimension covers, with respect to the statistics, their proximity between an estimate and the unknown true value. 

It is important to note that where totals are presented at National/Regional/ICB/Sub ICB level, these are aggregate totals based on the providers that submitted information.


Hopsital Episode Statistics

Sub-Integrated Care Boards

Organisations previously reported as Clinical Commissioning Groups (CCGs) are shown as Sub-Integrated Care Boards (ICBs) throughout the time series. Similar to Integrated Care Boards, these are based on latest boundaries as from 1 July 2022.

Procedures from Hospital Episode Statistics (HES) data 

The accuracy of HES data is the responsibility of the NHS providers who submit the data to Secondary Uses Service (SUS). 

Further general information on HES data quality, including specific known issues can be found here: 

The data presented in this report are for inpatients only. We have used primary diagnosis of obesity (ICD10 code E66), to limit the bariatric procedures to those related to obesity but there is a small possibility that people undergoing bariatric surgical procedures for cancer may be counted.  

The revision procedure count will not include patients; 

  • who had their first bariatric surgical procedure as a non-NHS patient in the private sector, or 

  • who had their first bariatric surgical procedure as an NHS patient earlier than 10 years prior to the reporting period year, or 

  • who had their first bariatric surgical procedure during the same reporting period year and both surgeries were coded as primary surgeries using one of the 13 primary procedure codes 

Outpatient data are not included in these figures due to the primary diagnosis code being poorly populated, and there being no certainty that any procedures are for obesity diagnoses. Outpatient appointments usually cover a short consultation – this may simply be a test or a scan.

In HES, people are identified using the Master Person Service (MPS) person identifier (Person ID). This is a unique identifier for each individual patient, generated via the MPS. HES is a well curated data asset, and most records (over the time period used in the NOA analysis) have NHS number and date of birth (DOB) populated. This means that Person ID matching is mostly based on the most robust tracing step in MPS. Further information on MPS is available here:  

Children's bariatric surgery 

The methodology used to derive these figures was designed with adults in mind. We aim to refine this methodology further and would welcome feedback on whether these figures are likely representative of the true picture for people aged 0-18 years. 


Weight Management Services (WMS) data from the Community Services dataset (CSDS)

The Community Services Dataset v1.6 went live for local data collection on 1 January 2023, and now allows us to identify specific activity in relation to Weight Management Services (WMS). This is where a Team Type for a WMS referral has been submitted in Table CYP102 using code 55 (for children) and 56 (for adults) . 

We would like to acknowledge and thank organisations who have correctly submitted or attempted to submit this information from v1.6.

There are a few points around data quality to highlight as completion of the following data tables and items are essential to capture key information needed for future reporting:


  1. Number of submitters

There are around 180 Weight Management Service providers across England, but at the present time we are only able to report on about 15% of these. Other Weight Management Service providers either are not submitting data yet (although many are actively working on this) or they have started to submit data but it doesn’t yet meet our requirements for inclusion in this dashboard. If you are from a Weight Management Service whose data is not yet included, we encourage you to read our guidance about submitting data to ensure your service features in future dashboards: Guidance on submission of WMS data to CSDS .

To join our mailing list to get notified when the dashboard is updated and for other NOA updates, please email: [email protected].

Any referrals for WMS need to be submitted with a TeamType code of 55 (for children) or 56 (for adults) in Table CYP102 (ServiceType Referred To). We need all future submissions to be recorded this way to provide a more accurate picture of WMS to inform interventions and policy. Please refer to the published guidance on how to submit with the correct Team Type codes: CYP102 Service or Team Type referred to 


  1. Completion of demographic information

Where available in Table CYP001 (Master Patient Index), the NHS number needs to be submitted to enable further analysis and reporting. Completion of this field is better from Tier 3 providers than Tier 2 providers who may not be able to access the NHS number as easily. Alternatively, if the NHS number is not available/ has not been submitted, we need all three data items for gender, date of birth and postcode to be submitted in order for us to complete further analysis and reporting.

This data will also help analysis of WMS information in future by allowing us to understand services according to patients' different demographic breakdowns.  Please refer to the published guidance on how to submit this data: CYP001 Master Patient Index


  1. Height and weight information

Submission of height and weight or BMI information in Table CYP202 (Care Activity) is key to looking at future reporting on patient outcomes , especially in terms of confirming the BMI of a patient at the start of a weight management programme and also at the end to check whether a weight loss outcome has been achieved.  Submission of this information at all care contact appointments in between these two points is helpful too. We have found that where there are multiple height and weight measurements across different care contact appointments, sometimes they are a duplicate from a previous appointment. We'd expect the height to be the same, but the weight to be (slightly) different (for adults anyway) at each care contact appointment. Table CYP202 is where the information needs to be recorded but for completeness, we have also looked at Table CYP611 (Observation) in case any information has been submitted there.

Submission of the height and weight and/or BMI information also helps us to categorise patients into BMI classifications and understand weight management pathways for these people.

We will be looking to use the BMI classification advised by the National Institute of Health and Care Excellence (NICE) which is

  • healthy weight: BMI 18.5 kg/m2 to 24.9 kg/m2
  • overweight: BMI 25 kg/m2 to 29.9 kg/m2

  • obesity: BMI 30 kg/m2 or above

People with a South Asian, Chinese, other Asian, Middle Eastern, Black African or African-Caribbean family background are prone to central adiposity and their cardiometabolic risk occurs at a lower BMI, so NICE advise using lower BMI thresholds as a practical measure of overweight and obesity:

  • overweight: BMI 23 kg/m2 to 27.4 kg/m2

  • obesity: BMI 27.5 kg/m2 or above.

Please refer to the published guidance on how to submit this data:CYP202 Care Activity 


Submissions to CSDS are being monitored by provider with information available via our published submission tracker: Community Services Data Set Submission Tracker

More generally, a CSDQ dasboard is updated each month which presents information about the quality of data submitted to Community Services Data Set (CSDS) each month which covers all types of community health services. This includes provider-level data quality information to help users understand the impact of local data quality issues. The purpose of this report is to support data quality improvement across all providers (not just WMS) that submit to CSDS. Community Services Data Set Data Quality Dashboard 

Timeliness and punctuality

Timeliness refers to the time gap between publication and the reference period. Punctuality refers to the gap between planned and actual publication dates. 

This is the fourth release of data to form part of NOA which includes HES updates to the quarterly time series for patients who had a primary bariatric surgical procedure in Q3 and Q4 in 2022/23. Subsequent releases are planned quarterly so the most up-to-date quarterly information is made available, as early as possible. This is similar for any annual updates.

For the new CSDS DQ metrics on Weight Management Services, data is dependent on timeliness of recording events on local systems.Whilst local systems may be continuously updated, the CSDS submission process provides two opportunities for data relevant to each month to be submitted, a primary submission and a refresh (or final) submission. The primary submission window opens two weeks before the reporting month end and remains open for a month. The refresh window then opens immediately with the submission window closing a month later. This means that the timeliness of recording all relevant activity on local systems has an impact on the completeness of the CSDS submission. For example, a referral made in January  2023, but not entered onto the local system until May 2023, will not be included in any reporting of January data . Providers should use the data summary reports produced at the point of submission to ensure that all relevant data has been included.

The submission requirements for CSDS are that all appropriate activity (e.g. referrals, care contacts, care activities etc.) be included in the submission for each month in which they start, continue or end. It is important that data providers ensure that NHS numbers are submitted consistently (or gender, date of birth and postcode in absence of NHS number) because this is a key piece of information for creating the person identifiers in our records.

The analysis in this report is based on the latest data submitted by providers during the two months-long windows to provide data. Any data which are re-submitted by a provider during the submission window will be used in place of an earlier submission within the window. We have used the 'last good' file that has passed validation by the submission deadline for this report.


Accessibility and clarity

Accessibility is the ease with which users are able to access the data, also reflecting the format in which the data are available and the availability of supporting information. Clarity refers to the quality and sufficiency of the metadata, illustrations and accompanying advice. 

All reports are accessible via the HTML website. Data are provided in the dashboard and/or as a csv file, as part of the government’s requirement to make public data public. An accompanying metadata file is provided in MS Excel format which provides a broad definition of each measure, including the data items used. There are separate files for HES and CSDS reporting.

Coherence and comparability

Coherence is the degree to which data which have been derived from different sources or methods but refer to the same topic are similar. Comparability is the degree to which data can be compared over time and domain. 

NBSR data 

BOMSS also collect and publish annual data on bariatric surgery through the National Bariatric Surgery Registry (NBSR) which allows surgeons to voluntarily submit data. The key objective of the registry is to accumulate sufficient data to allow the publication of a comprehensive report on outcomes following bariatric surgery. The latest NBSR report was published in 2020 at  

There are some differences in the data collected by NBSR and HES. The data is collected for different primary purposes with NBSR collecting much broader data, different coding/terms are used for procedures, NBSR includes all adult NHS and private procedures, and not all hospitals submit complete data to NBSR. However, the data are relatively coherent, with large provider differences highlighted on the NBSR website. Full details of NBSR and their reports are on the Bariatric Surgeon Reporting Website ( 

NHS England continue to work together with BOMSS to ensure both NBSR and HES provide reliable data which support improvements in quality of care. 

Data in the Statistics on Obesity, Physical Activity and Diet publication 

NHS England (previously NHS Digital) has historically published data on admissions and number of finished consultant episodes for bariatric surgical procedures in the National Statistics on Obesity, Physical Activity and Diet (SOPAD) which uses a different methodology, as explained in their Technical notes. SOPAD counts the number of procedures and admissions for bariatric surgery,  groups reporting on primary and revision procedures, excludes gastric balloon procedures and uses a wider range of different procedure codes. Therefore the SOPAD figures are higher than the counts of people provided in this release. SOPAD have recently been through a consultation, accessible here: Statistics on Obesity, Physical Activity and Diet  which didn’t include a revised methodology for these estimates. Therefore, as this dashboard and statistics develop, we will consider in liaison with stakeholders and users, whether these statistics continue to be published separately from SOPAD or realign back into SOPAD with the revised methodology, as part of a new combined compendia publication following the consultation. 

Obesity related hospital admissions 

Changes to the figures over time need to be interpreted in the context of improvements in data quality and coverage, and changes in NHS practice. 

Improved use of secondary procedure codes 

There is continuing evidence that recording of secondary procedure codes is improving over time, which result in an increase in the number of people identified as having a bariatric procedure. 


NHS England publishes data from the National Child Measurement Programme (NCMP).  This programme is part of the Government’s approach to tackling child obesity by annually measuring the height and weight of children in reception (aged 4–5 years) and year 6 (aged 10–11 years) in mainstream state-maintained schools in England. Data is very well completed and so provides a more reliable source of child BMI information than CSDS for these age groups.

Trade offs between output quality components

This dimension describes the extent to which different aspects of quality are balanced against each other. 



New analyses by NHS England consist of HES statistics. HES data quality information, including details of trade-offs, is available here: 


CSDS for WMS data

This is a developing set of metrics based on Experimental Statistics from CSDS.  The format of this publication meets initial user needs around data quality information on weight management services in England.

The CSDS provides a much greater scope of analysis and reporting once the coverage and completeness of certain key fields for WMS improve.  This will also support a variety of local uses. 

The format of this publication meets our obligations under the Code of Practice for National Statistics and the Transparency Agenda.

The format of this publication balances the need for quarterly reporting and scope of analysis with NHS England resources and production time. NHS England is supporting the Open Data initiative by also publishing data in a machine-readable format. By publishing a range of clearly defined dimensions and measures in a timely fashion, we hope to support discussions with providers about caseload and activity and promote a virtuous cycle of improving data quality through use.


Assessment of user needs and perceptions

This dimension covers the processes for finding out about users and uses and their views on the statistical products. 

This is the fourth release of data to form part of NOA. 

NHS England is keen to gain a better understanding of the users of this publication and of their needs; feedback is welcome and may be sent to [email protected] (please include ‘NOA’ in the subject line). 

You may feedback your comments on this using our customer survey

To join our mailing list to get notified when the dashboard is updated and for other NOA updates, please email: [email protected]

Confidentiality, transparency and security

The procedures and policy used to ensure sound confidentiality, security and transparent practices. 

The code of practice for statistics is adhered to from collecting the data to publishing. 

All publications are subject to a standard NHS England risk assessment prior to issue. Disclosure control is implemented where deemed necessary.

HES data

Please see HES Disclosure Control for rules around the presentation of data.


CSDS for WMS data

Since CSDS v1.5, the dataset has adopted the central suppression method. This applies to all levels of aggregation including national level totals.

  • Zeroes will be unchanged.
  • Sub-national counts between 1 and 7 (inclusive) will be displayed as 5.
  • All other counts will be rounded to the nearest 5.
  • Percentages are calculated on rounded numerators and denominators.


Please see links below to relevant NHS England (previously NHS Digital) policies:

Last edited: 13 July 2023 8:52 am