The HES Data Dictionary contains detailed information on the fields from the admitted patient, outpatient, accident and emergency and adult critical care data sets that are collected and used in HES and the Patient Reported Outcome Measures (PROMs) data set. These include those submitted directly by the data providers and also fields we derive and add to the data sets.
The HES Data Dictionary also identifies which cleaning or derivation rules have been applied to which fields. The cleaning rule definitions, used in conjunction with the HES Data Dictionary, are available on the processing cycle and HES data quality page.