The accuracy of HES data is the responsibility of the NHS providers who submit the data to the Secondary Uses Service (SUS). This data is required to be accurate to enable providers to be correctly paid for the activity they undertake.
SUS is the single, comprehensive repository for healthcare data in England which enables a range of reporting and analyses to support the NHS in the delivery of healthcare services.
When a patient or service user is treated or cared for, information is collected which supports their treatment. This information is also useful to commissioners and providers of NHSfunded care for 'secondary' purposes - purposes other than direct or 'primary' clinical care - such as:
- healthcare planning
- commissioning of services
- national tariff reimbursement
- development of national policy
SUS is a secure data warehouse that stores this patient-level information in line with national standards and applies complex derivations which support national tariff policy and secondary analysis.
A list of mandatory and optional fields for submission in in the Commissioning Data Set (CDS) is provided within the NHS Model and Data Dictionary:
- CDS V6-2 Type 120 – Finished Birth Episode CDS
- CDS V6-2 Type 140 – Finished Delivery Episode CDS
- CDS V6-2 Type 150 – Other Birth Event CDS
- CDS V6-2 Type 160 – Other Delivery Event CDS
NHS Digital has a well-developed data quality assurance process for the SUS and HES data. It uses an xml schema to ensure some standardisation of the data received. The use of the schema means that the data set has to meet certain validation rules before it can be submitted to SUS. NHS Digital leads on the schema changes and consults the data suppliers about proposed changes.
Each month NHS Digital create data quality dashboards available to NHS providers to show the completeness and validity of their data submissions to SUS. This helps to highlight any issues present in the provisional data allowing time for corrections to be made before the annual data is submitted.
An external auditor, acting on behalf of the Department of Health (DH), audits the data submitted to SUS to ensure NHS providers are being correctly paid by Payment by Results (PbR) for the care they provide.
NHS Digital validates and cleans the HES extract and derives new items. The team discusses data quality issues with the information leads in hospital trusts who are responsible for submitting data. The roles and responsibilities within NHS Digital are clear for the purposes of data quality assurance, to assess the quality of data received against published standards and report the results.
Data quality information for each year to date HES dataset is published alongside the provisional year to date HES data, and also alongside annual publications. These specify known data quality issues each year and where a trust has a known shortfall of secondary diagnoses. The statisticians can only check the validity and format of the data and not whether they are accurate, as accuracy checking requires a level of audit capacity and capability which NHS Digital does not currently possess.
There is also further information about HES data quality published online: https://digital.nhs.uk/data-and-information/data-tools-and-services/data-services/hospitalepisode-statistics/the-processing-cycle-and-hes-data-quality
NHS Digital also publishes an annual report The Quality of Nationally Submitted Health and Social Care Data, which highlights issues around the recording of the underlying data that is used for HES, as well as examples of good and poor practice, and a regular Data Quality Maturity Index for providers across several datasets including HES: https://content.digital.nhs.uk/dq
The UK Statistics Authority conducted case studies of quality assurance and audit arrangements of administrative data sources. HES was used as a case study and further information can be found in the published report (Annex C, case study 3), available at: https://www.statisticsauthority.gov.uk/osr/systemic-reviews/administrative-data-and-officialstatistics/quality-assurance-and-audit-arrangements-for-administrative-data/