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Hospital Episode Statistics data changes in 2021

From April 2021 we are making changes to the way we process the Hospital Episode Statistics (HES) data set.  These improvements will provide data users with the tools to process larger volumes of data and manage incoming data to ensure that it is accurate, useful and secure.

Summary of changes

Data users will see changes to HES in the following ways:

  • the introduction of the MPS Person ID will enable direct linkage of patient records across data sets, reducing the time and complexity in the analysis of HES data
  • the HES_ID field will be retired along with a list of other fields that are no longer valid
  • reference data will reflect real time changes in organisations  

These changes will help to increase the amount of linkable data available to support research and planning.

These changes will help us

  • improve matching of patients across all national patient-level datasets through the Master Person Service
  • reduce the burden on data senders by retiring aggregate flows
  • improve data quality, coverage and timeliness
  • allow our customers to self serve 
  • exploit new analytical and data science capabilities
  • increase efficiency through automation
  • reduce cost by retiring legacy systems

All users of HES data will be affected by these changes but please note that the data submitted to SUS+ is not affected.

MPS Person ID

From April 2021, the patient identifier in HES will change from HESID to the Master Person Service (MPS) person Identifier (MPS Person ID). The MPS Person ID will be the biggest change to HES and is part of a wider strategy to move to a common patient identifier across all national patient level data sets.

MPS Person ID will support data users to

  • measure counts of patients rather than attendances, appointments, episodes
  • link together activity in the data relating to the same patient such as continuous inpatient spells
  • Identify and track specific patient cohorts across time

MPS Person ID confirms the individuals identity using PDS data on Spine and assigns a common ID across all NHS Digital data sets.

A detailed analysis of the changes to HES and how this impacts data and statistics can be found in the methodological change paper.  

Reference data

How we handle reference data in HES to align to other data sets, such as Secondary Uses Service (SUS+) and Mental Health Services Data set (MHSDS), collected by NHS Digital is also changing. SUS+ currently maps data based on the valid reference data on activity date than at the end of the reporting period.  HES will now adopt this approach so that data in the asset will show activity at submission rather than the end of the reporting period.  

Retiring the HESID and other fields

With the upcoming move to utilising the MPS Person ID in the HES data we will be retiring the HESID field from April 2021. We will also be retiring fields from HES that are no longer valid, a list of the fields scheduled to be retired can be found on the HES data dictionary The fields will continue to appear in extracts to help make transition easier for users receiving extracts, but will contain null values.


All HES products, from June 2021, will contain TOKEN_PERSON_ID only. 

Any HES data received from June 2021 will contain TOKEN_PERSON_ID instead of HES_ID.

The overall structure of HES data will not change. For a period of time, your HES data will still contain HES_ID field, but this will not be populated for activities recorded past March 2021. Instead, data referring to activities recorded from April 2021 onwards, will contain TOKEN_PERSON_ID. 

DARS Data Sharing Agreements (DSAs)

DARS customers will not need to make any changes outside their usual renewal schedule. However, if you are currently working on your affected Data Sharing Agreement (DSA) you may be able to update it. Please speak to your case officer for further information.

TOKEN_PERSON_ID  is available to select on DARS Online from November 2020.

Should you need to, HES_ID will be available to select on DARS Online until February 2021.

To receive your first drop off date with TOKEN_PERSON_ID your DSA will need to be signed off and active by June 2021.  

If you would like to make changes to your fields when you are renewing your DSA please speak to your case officer so they can arrange these changes for you, as you will not be able to make changes to your fields online. 

There will be no additional charge for adding TOKEN_PERSON_ID to your application.  

We have reviewed the list of variables within HES data and identified fields that are no longer populated. Whilst those retired fields are still available to select on DARS Online as they are valid for historical data they are not populated. Therefore, we strongly advise you to review the list of retired fields before selecting your HES variables on DARS online.         

Linking files to existing data

If you have received HES data (as extracts) before June 2021 and are requesting further HES data, you will receive a HES Person ID bridge file to enable you to attribute TOKEN_PERSON_ID to any historic data you hold. There is no intention to re-supply any HES data provided prior to June 2021.

If you did not receive HES_ID the assumption will be that you also do not require TOKEN_PERSON_ID, unless you tell us otherwise during your application process in which case you will need to make an amendment to your application. You will continue to receive your local identifier or Study_ID to track patients as before.

HES admitted patient care bridge files are linkable to historical HES admitted patient care data using the EPIKEY field.

HES outpatient bridge files are linkable to historical HES outpatient data using the ATTENDKEY field.   HES accident and emergency bridge files are linkable to historical HES accident and emergency data using the AEKEY field.

This will be supplied on a case by case basis, allowing you to assign TOKEN_PERSON_ID to your historical data, in place of HES_ID. From 2021/22 onwards data will be supplied with TOKEN_PERSON_ID so no further bridge files will be supplied.

If you receive new copies of historical HES data frequently, you will not need the bridge file as these will be supplied with TOKEN_PERSON_ID in future. You will therefore have a consistent person identifier (TTOKEN_PERSON_ID) across all data years.  

Bridge file

Data item  Description  Format 


Unique record identifier



Pseudonymised Person Identifier



Indicates quality of the date of birth linkage. 0 if no match is found or attempted

Decimal (5,2)


Indicates quality of the family name linkage. 0 if no match is found or attempted

Decimal (5,2)


Indicates quality of the gender linkage. 0 if no match is found or attempted

Decimal (5,2)


Indicates quality of the given name linkage. 0 if no match is found or attempted

Decimal (5,2)


Indicates quality of the postcode linkage. 0 if no match is found or attempted

Decimal (5,2)


Indicates the linkage methodology used:0 = No Match1 = Cross Check2 = Simple trace3 = Alphanumeric4 = Algorithmic

Please note value 2 will not appear as Simple trace has been removed from the trace methodology.



Total % linkage confidence score (0 or 100% for cross check, simple and alphanumeric linkages, weighted and aggregated average for algorithmic linkages)

Decimal (5,2)


Further information

  1. internal

    Hospital Episode Statistics Data Dictionary

    The Hospital Episode Statistics (HES) Data Dictionary is intended for use by all users of HES data. An NHS data dictionary works in the same way as a normal dictionary, but contains information about data items.

  2. internal

    Data Access Request Service (DARS)

    The Data Access Request Service (DARS) can offer clinicians, researchers and commissioners the data required to help improve NHS services. We handle applications, process data and provide access to specific sets of data when requests are approved.

  3. internal

    Master Person Service (MPS)

    Master Person Service (MPS) is an enhanced patient-matching algorithm that increases the number of linkable records where incomplete records have been submitted.

Last edited: 7 December 2020 5:30 pm