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Publication, Part of

Hospital Outpatient Activity 2019-20

National statistics

National Statistics

Further information about HES

Further information about HES

The NHS Digital website contains more background information about HES

Alongside this publication a Statement of Administrative Sources is also published, as required by the Code of Practice for Official Statistics.

Accessing HES

The HES publications focus on headline information about hospital activity. Each annual publication includes a series of national tables and also provider-level breakdowns for some main areas.

All data items included in the published tables are explained in footnotes, and NHS Digital publish data dictionaries for HES describing the format and possible values for all HES data items.

These data are also readily accessible via an online interrogation service (for NHS users) or via our bespoke extract service DARS.


Clinical Classifications

Diagnoses are coded in HES using the ICD10 classification.

Operative procedures are coded in HES using the OPCS classification.

Further information about these classifications, and changes to them is available. 


Changes to organisation codes and geographical boundaries

The Organisation Data Service (ODS) is responsible for the publication of all organisation and practitioner codes and national policy and standards with regard to the majority of organisation codes. 


Accessibility and Clarity

As HES is such a rich source of data it is not possible to publish aggregate tables covering all permutations of possible analysis. Underlying HES data is also made available to facilitate further analysis that is of direct relevance to users. There are no restrictions to access the published data.

Trade-offs between Quality Components

As discussed in the Accuracy and Reliability section providers have the opportunity to submit data each month, which is centrally assessed for data quality and issues are reported back to providers in order to give an opportunity to address any issues found. The dataset is then finalised for the full financial year, and issues remaining after that point are published on NHS Digital’s website, but no attempt is made to amend the data.   

Assessment of User Needs and Perceptions

We have a dedicated e-mail address for users to e-mail their views, suggestions, queries or concerns regarding the publication.  If anything is identified as being unclear, we address that as soon as we possibly can. 

We consult users when proposing significant changes to the content of or methodologies used in the publications.

In addition, in 2016 NHS Digital conducted a wider consultation exercise on all its publications and services, including HES, and the outcome is available to all. 


Cost, Performance and Respondent Burden

The production of HES data is a secondary use of data collected during the care of patients in the NHS and submitted for NHS Providers to be paid for the care they deliver. Therefore HES does not incur additional costs or burden on the providers of the data. 

Confidentiality, Transparency and Security

Although certain information is considered especially sensitive, all information about someone's health and the care they are given must be treated confidentially and in accordance with legislation and NHS Digital protocols at all times.

There are a limited number of people authorised to have access to the record level data, all of whom must adhere to the written protocol issued by NHS Digital on the dissemination of HES data. For example, guidance is given on handling the very small numbers that sometimes occur in tables to reduce the risk that local knowledge could enable the identification of either a patient or clinician.

HES is a record level data warehouse and it contains information that could (if it was made freely available) potentially identify patients or the consultant teams treating them. In some cases record level data may be provided for medical/health care research purposes. For example, data are likely to be required by the Care Quality Commission and other such bodies. The information may be given following a stringent application procedure, where the project can justify the need and where aggregated data will not suffice. Any request involving sensitive information, or where there may be potential for identification of an individual, is referred to the appropriate governance committee. NHS Digital publishes a quarterly register of data releases, which includes releases of HES data.

HES data are stored to strict standards: a system level security protocol is in place. This details the security standards that are in place to ensure data are secure and only accessed by authorised users.

Last edited: 13 January 2022 10:52 am