Introduction to the processing cycle

HES data for admitted patients, outpatients and A&E; comes from the routine exchanges of information between providers of healthcare for NHS patients in England and the commissioners of the care.

Healthcare providers collect administrative and clinical information locally to support the care of the patient. The data is submitted to the Secondary Uses Service (SUS), which, as well as making it available to the commissioners, also copies the information to a database.

At pre-arranged dates during the year, SUS takes an extract from their database and sends it to HES. Data on SUS will continue to change, but HES data is fixed as it was when that particular extract was taken. This is why there are likely to be differences between analyses from SUS and those from HES.

HES then validates and cleans the extract, before deriving new items and making the information available in the data warehouse. Data quality reports and checks are completed at various stages in the cleaning and processing cycle.

The HES Data Warehouse also includes information on the date of death (when a patient with a record in HES dies) taken from the Office of National Statistics (ONS) mortality statistics.