1. Introduction#

The Emergency Care Data Set (ECDS) was introduced in 2017 and is the national dataset for emergency care in England. It records information about why people attend emergency departments and any treatment they are given.

2. Strengths of ECDS#

1. It is longitudinal making it possible for researchers to study cohorts over time

2. It provides complete coverage of all NHS emergency departments in England

3. The severity of cases is recorded

4. It uses a standardised coding system, enabling comparative work to be undertaken over time and internationally

3. Limitations of ECDS#

1. It is a clinical dataset, rather than one specifically designed for research

2. Coding is unlikely to be consistent as there are variations between hospitals and over time

3. The dataset was only established in 2017 so there is limited longitudinal value in using ECDS alone

4. Patient-level data from all NHS emergency departments, urgent treatment centres and some walk-in centres is included

4. Scope and coverage#

The dataset contains patient-level information about:

• diagnoses

• outcomes

• referral sources

• dates and times of arrival and departure

• waiting times

• discharge destination

• patients’ stated gender, age, ethnic group and geographic location

5. Data collection methodology#

Data about each attendance at an A&E department are input into local record systems by clinicians and administrative staff. Some data (e.g. postcode, date of birth) are generated automatically from local patient administration systems.

6. Structure of the dataset#

Each record (line) represents a single visit to an emergency care department.

Clinical information: Each record contains coded information on the ‘chief complaint’ (main reason for attending A&E) and up to 10 comorbidities (fields comorbidities_1 to _10). There also up to 12 coded fields for diagnoses, investigations and treatments.

Dates and times: The ECDS includes multiple date and time fields which facilitate the tracking of a patients’ progress through A&E experience from arrival to discharge, e.g. ‘arrival_date’ (ddmmmyyyy) and ‘arrival_time’ (hh:mm:ss).

Other information: The dataset also provides broader information such as which care professionals were involved in a patient’s care while they were in A&E, and the discharge destination (e.g. home, admitted to hospital).

7. Coding systems used#

The ECDS uses SNOMED CT (Systematized Nomenclature of Medicine Clinical Terms), usually abbreviated to just SNOMED. It is an international system used to classify many types of medical data, including diagnoses, procedures, symptoms, family history, assessment tools, observations and medications. SNOMED CT is designed for direct management and care of patients. The codes are numeric, typically between 6 and 18 digits long, and do not follow a pattern or hierarchy.

The UK edition of SNOMED CT contains the UK extensions, which include UK-specific screening procedures and assessment scales. There are also ECDS-specific SNOMED codes (known as ECDS Diagnosis Core and ECDS Diagnosis Max).

8. Evolution of the dataset#

NHS England started collecting A&E data, as (HESAE), in 2007-08. It was an ‘experimental’ dataset until 2012-13 when data collected in emergency departments became a national standard for official statistics. The ECDS (Emergency Care Data Set) was introduced in 2017, remaining ‘experimental’ until it ECDS replaced HESAE as the national standard in 2020.

Rather than SNOMED codes, HESAE used National Codes so the two datasets cannot easily be compared or combined.

9. Availability in the UK LLC TRE#

The UK LLC TRE holds an extract of the ECDS, going back to 2017 when it was first established. The ECDS records of participants in UK LLC’s partner LPS, where individual or LPS permissions allow linkage to NHS data, are included in the TRE. UK LLC does not hold any information about people who are not part of a partner LPS or about LPS participants who have requested that their NHSE data not be shared via UK LLC.

More detailed information about the UK LLC’s ECDS extract is here.

10. UK LLC transformations of the dataset#

All variables which identify organisations (e.g. GP practice, NHS Trust) or geographic areas smaller than a region (e.g. LSOA) are encrypted before being ingested into the UK LLC TRE. The encrypted variables (identifiable by the suffix _e) enable researchers to identify which participants were treated by the same organisation, or live in the same area, but not to identify the organisation or area.

11. Tips for researchers using ECDS in the UK LLC TRE#

Key variables in the ECDS

The full HES data dictionary can be downloaded from NHS England.

12. Useful syntax#

Below we will include syntax that may be helpful to other researchers in the UK LLC TRE. For longer scripts, we will include a snippet of the code plus a link to the UK LLC Github repository where you can find the full scripts.

13. Further reading#

Information in this section will be added in due course.