5  Health data

The data collections detailed below are supplied by NHS England. NHS England is responsible for the collation of all these except for birth and death registration data, these are collated by the Office for National Statistics.

5.1 Hospital Episode Statistics

HES contains hospital records for all NHS patients in England, including patient demographics and standardised codes for diagnoses, symptoms and procedures relating to the care they have received (NHS England, 2023g). The datasets are collected by NHSE from hospital care providers and curated on an ongoing basis. However, data from other health providers such as General Practitioners (GPs) or pharmacies are not included. HES datasets are collated by financial year (1st April to 31st March) and following processing and quality assessment, the finalised datasets are released for secondary use and remain unchanged thereafter (Boyd et al., 2018).

5.1.1 Admitted Patient Care

Records within the Admitted Patient Care (APC) dataset are called ‘hospital episodes’, and each episode relates to a period of care for a patient under a single consultant (consultant episode) within one hospital provider (Herbert et al., 2017; Boyd et al., 2018; Health Data Research, 2023b). The time from initial admission to discharge is called a ‘spell’, defined as ‘periods of continuous care in one provider institution’ and each admission spell can be made up of many episodes. APC data contain ‘Finished Admission Episodes’ (FAEs) which is the first episode in a spell of care, and ‘Finished Consultant Episodes’ (FCEs), which is a continuous period of care under one consultant. Only FCEs concluded within the financial year (from 1st April to the end of 31st March) are included. Patients with an unfinished consultant episode in the current financial year will have their record represented as a finished episode in the next financial year of HES data.

5.1.1.1 Inpatient spell (single hospital)

A hospital admission commences when a patient is initially admitted for care and ends when a patient is discharged, transferred, or dies.

One spell of admission encompasses multiple episodes of care under a different consultant.

5.1.1.2 Continuous Inpatient spell (across multiple hospitals)

In some instances, admitted patients who require specialised treatment may be transferred from one hospital to another more specialist hospital, e.g., transfer to a Children’s hospital.

5.2 Data collections

5.2.1 Acute Hospital Admitted Care data collections

Dataset	Years	Details
Admitted Patient Care (APC)1	1997 to 2023	Episode-level dataset of patients admitted for treatment (i.e., requiring the use of a hospital bed), at NHS hospitals in England; includes delivery and birth data, up to 20 diagnostic codes per episode and procedure codes (Herbert et al., 2017; Health Data Research, 2023b; NHS England, 2024a).
Critical Care (CC)2	2007 to 2023	Episode-level dataset of patients admitted for treatment and receiving Critical Care (intensive care or high dependency care) at NHS hospitals in England. Treatment in adult designated wards where constant support and monitoring are required to maintain at least one organ (i.e., an Intensive Care or High Dependency Unit) (Health Data Research, 2023c; NHS England, 2024b).

5.2.2 Acute Hospital Attendance data collections

Dataset	Years	Details
Outpatients (OPA)3	2003 to 2023	Outpatient appointments at English NHS hospitals and NHS commissioned activity in the independent sector (regardless of whether the appointment was attended or not) (NHS England, 2023i; Health Data Research, 2023d). In 2003/04, the OP module was considered experimental and did not have complete coverage as not all providers completed data submissions.
Accident & Emergency (A&E)4	2007 to 2020	Attendance level dataset collecting information about the treatment received by patients attending A&E Departments, Minor Injury Units and Walk-In Centres, in England (NHS England, 2023e; Health Data Research, 2023a). Please note diagnoses aren’t consistently captured in A&E records.
Emergency Care Data Set (ECDS)5	2020 to 2023	In 2018, the A&E dataset was replaced by the ECDS which is now the national dataset for Urgent & Emergency care (NHS England, 2023d, 2023c; Health Data Research, 2023a). Please note diagnoses aren’t consistently captured in ECDS records.

5.2.3 Mental Health data collections

Dataset	Years	Details
Mental Health Services Data Set (MHSDS)	2016 to 2023	Patient-level dataset that records all activity relating to patients who receive assessments and treatment from Mental Health Services in England, where the patient has (or is thought to have): either a mental health condition; a need for support with their mental well-being; a learning disability; autism; or any other neurodevelopmental condition (NHS England, 2023m). Note: MHSDS includes data supplied by both Children and Young People’s (formerly known as Child and Adolescent) mental health services, and adult mental health services.
Mental Health & Learning Disabilities Data Set (MHLDDS)	2014 to 2016	MHLDDS is collected from adult mental health services (NHS England, 2024c). Note: MHLDDS includes data supplied by adult mental health services only.
Mental Health Minimum Data Set (MHMDS)	2006 to 2016	The MHMDS was the preliminary dataset capturing data about the use of adult Mental Health Services in England. However, the MHMDS was superseded by the Mental Health & Learning Disabilities Data Set, which in turn was superseded by the MHSDS (NHS England, 2024c). Note: MHMDS includes data supplied by adult mental health services only.

5.2.4 Maternity and Birth data collections

Dataset	Years	Details
Maternity Services Data Set (MSDS)	2015 to 2023	The MSDS is a patient-level dataset that captures information about activity carried out by Maternity Services relating to a mother and baby(ies), from the point of the first booking appointment until the mother and baby(ies) are discharged from maternity services. The MSDS collects records of each stage of the maternity service care pathway in NHS-funded maternity services and includes information not recorded in HES (NHS England, 2023a; Health Data Research, 2023e).
Birth Notification Data	2001 to 2023	Birth notification is a document completed by the doctor or midwife present at birth occurring in an NHS facility in England, Wales and the Isle of Man. The baby’s NHS Number is issued as part of the ‘statutory notification of birth’. Birth notification data includes information that is not found in the birth registration data such as gestation age and ethnicity of the baby as stated by the mother (NHS England, 2023b).
Birth Registration Data	1996 to 2022	Birth Registration Data includes information recorded when births are registered. It is a legal requirement to register all births in England and Wales. These registrations are lodged with a local registry office and collated by the General Register Office (for England and Wales). The General Register Office shares these data with the Office for National Statistics which processes these data and further shares the data with NHS England. All registered live births are included except very late registrations received more than 14 months after the end of each reference year (there are fewer than 100 of these for any given year) (Office for National Statistics, 2024). Note: Birth Registration Data in ECHILD does not contain records relating to stillbirths due to how the ECHILD cohort is defined.

5.2.5 Other data collections

Dataset	Years	Details
Death Registration Data	1998 to 2023	It is a legal requirement to register all deaths in England and Wales. Death registrations are lodged with a local registry office and collated by the General Register Office (for England and Wales). The General Register Office shares these data with the Office for National Statistics which processes these data and further shares the data with NHS England. Death Registration Data contains information taken from death certificates for all deaths registered in England and Wales and includes cause of death, date and place of death. Information related to stillbirths is not available in this data, see Birth Registration Data. Some deaths, particularly those referred to a coroner, may not be registered until long after the date of death.
Community Services Data Set (CSDS)	2015 to 2023	The CSDS captures activity data about children and adults collected by Community Services, including health visiting teams. Such activities may take place in settings such as Health centres; Day care facilities; Schools or Community centres; Mobile facilities, or a patient’s own home (NHS England, 2023j). Data are collected about children and adults e.g., personal, demographic or social circumstances; breastfeeding and nutrition; long-term conditions (disabilities), diagnoses and scored assessments. The CSDS is comprised of patient-level data from all publicly funded community services providers e.g., Foundation or Non-Foundation Trusts; Acute Trusts; Mental health Trusts, Community Healthcare Trusts, Independent sector providers and Local Authorities. CSDS data are inconsistently captured over time; meaningful interpretation of data prior to 2018/19 is challenging (Clery et al., 2024).

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Feng, Q. et al. (2024b) “Data resource profile: ECHILD only-children and siblings (ECHILD-oCSib): A national cohort of linked health, education and social care data on mothers and children in england,” IJPDS, 8(6). doi:/10.23889/ijpds.v8i6.2392.

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Harron, K. et al. (2017) “A guide to evaluating linkage quality for the analysis of linked data,” Int J Epidemiol, 46, pp. 1699–1710.

Health Data Research (2023a) “Innovation gateway: Hospital episode statistics accident and emergency (HES a&e).” Available at: https://web.www.healthdatagateway.org/dataset/101a7d68-1675-4b47-bfac-dde7b7b57877.

Health Data Research (2023b) “Innovation gateway: Hospital episode statistics admitted patient care (HES APC).” Available at: https://web.www.healthdatagateway.org/dataset/6599230a-df54-4615-937c-d724d239491f.

Health Data Research (2023c) “Innovation gateway: Hospital episode statistics critical care (HES CC).” Available at: https://web.www.healthdatagateway.org/dataset/d0eeba22-bc3f-4c40-be69-a99f916897a2.

Health Data Research (2023d) “Innovation gateway: Hospital episode statistics outpatients.” Available at: https://web.www.healthdatagateway.org/dataset/d4362d41-0838-4f41-bba3-c3268312c444.

Health Data Research (2023e) “Innovation gateway: Maternity services data set (MSDS).” Available at: https://web.www.healthdatagateway.org/dataset/0681a1e9-3778-4f43-88b3-6540515404b6.

Herbert, A. et al. (2017) “Data resource profile: Hospital episode statistics admitted patient care,” Int J Epidemiol, 46(4), pp. 1093–1093i.

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Mc Grath-Lone, L., Harron, K., et al. (2016) “Data resource profile: Children looked after return (CLA),” Int J Epidemiol, 45(3), pp. 716–717f.

Mc Grath-Lone, L., Libuy, N., Harron, K., et al. (2021) “Data resource profile: The education and child health insights from linked data (ECHILD) database,” Int J Epidemiol, 51(1), pp. 17–17f.

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1. Bespoke codes are used to record diagnoses and treatments (NHS England, 2023f); however, these are much more limited than ICD-10 and OPCS-4 codes. Prior to 2012/13, the A&E module was considered experimental and did not have complete coverage as not all providers completed data submissions (NHS England, 2023e).

2. ECDS uses a subset of SNOMED CT codes to record diagnoses and treatments (amongst other variables) (NHS England, 2023d, 2023c).

3. Diagnoses are recorded using the International Classification of Disease (ICD) version 10 and procedures are recorded using the Office of Population Censuses and Surveys (OPCS) version 4. Diagnoses and procedures have very low levels of completeness in the Outpatient dataset (5% and 26%, respectively) (Boyd et al., 2018).

4. See footnote 1.

5. See footnote 1.