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The processing cycle and HES data quality

Hospital Episode Statistics (HES) data comes from the routine submissions of data from providers to NHS Digital for the purposes of payment for and commissioning of healthcare in England.

Changes to HES, August 2021

Automatic data cleaning and derivation rules documentation and the HES Patient ID sections have been removed from this page. Information on data cleaning and derivations can now be found in the HES Technical Output Specification found on the HES Data Dictionary.

For activity occurring from April 2021, the patient identifier in HES will change from HESID to the Master Person Service (MPS) person Identifier (MPS Person ID). This change will take effect from the April to July 2021 year to date provisional HES data release in September 2021 and will be applied to all previous years of HES data .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.

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

Emergency care data quality

Learn more about Emergency Care Data Quality at the data quality information and reports on the Emergency Care Data Set (ECDS).

HES processing cycle 

Healthcare providers collect administrative and clinical data locally to support the care of the patient. The data is submitted to the Secondary Uses Service (SUS).

At pre-arranged dates during the year, SUS consolidates those submissions and compiles the data as HES. It is then validated and cleansed, before deriving new items and making the information available in a database. Data quality reports and checks are completed at various stages in the cleansing and processing cycle.

SUS and HES data quality

This interactive report provides a summary of high level counts of the extracts taken from SUS+. The first page gives a breakdown of number of records extracted by data set - Accident and Emergency (AE), Outpatient (OP) and Admitted Patient Care (APC) - and by organisation number and type (NHS and independent providers). The second page shows the number of records deleted from the SUS extract and the reason for the deletion. These removed records will not appear on the final HES data set. The third page offers some notes to clarify concepts or atypical trends.  

Learn more about data quality checks performed on SUS and HES data

Accessibility of this tool

This tool is in Microsoft PowerBI which does not fully support all accessibility needs.  

If you need further assistance, please contact us for help.

HES data quality notes

Latest activity period: December 2023

Latest publication date: 8 February 2024

Important information

Due to processing issues, it was not possible to produce a month 5 version of the DQ Notes.

Understanding volume of legally restricted codes in HES: April 2017 - March 2018

This document provides HES users a count of legally restricted records in HES from April 2017 - March 2018, by provider, for Admitted Patient Care and Outpatients. It highlights the differences in counts due to additional codes added by SUS+ that have since been reverted.


Duplicate methodology

How we identify and handle duplicate records within the HES dataset.


Provider mapping methodology

How we handle records with an invalid provider code within the HES datasets.


SUS admitted patient care data

NHS Digital routinely collects data from hospital providers regarding a patient's time at hospital as part of the Commissioning Data Set (CDS). This is then processed and is returned to healthcare providers as the Secondary Uses Service (SUS) data set and is used by the NHS for operational purposes.

Most NHS hospital trusts submit data on a monthly basis by deadline following a two-phase reconciliation process to arrive at a final agreed position for each month's activity defined in the NHS Standard Contract for payment purposes. This data is consolidated, validated and cleaned and then used to create the Hospital Episode Statistics (HES) data set which is released on a monthly basis as official statistics.

Further information

internal Master Person Service (MPS)

The Master Person Service (MPS) helps us increase the amount of usable, better-quality data available to support research and planning.

Last edited: 7 February 2024 2:45 pm