Information about health, healthcare, births and deaths

SAHSU maintains a large data collection of health records and population-based data that allows us to study trends in chronic disease including environmental risks. To protect the health of the population and improve health care outcomes, we need data on the entire population in order to investigate national environmental health concerns, conduct disease surveillance and detect disease clusters.

Our health data collection consists mainly of the following:

• Hospital Episode Statistics (HES) - All admissions for Admitted Patient Care, Critical Care and attendances for Emergency Care at NHS hospitals in England,
• Cancer registrations (England and Wales),
• Death, live birth and still birth registrations/notifications.

Our major and unique features of SAHSU are our wide range of environmental and health data and our expertise in handling health data at the small area (neighborhood) level. Our national health data are stored, processed, and analysed within the SAHSU Secure Research System (SSRS) facility consisting of two separate secure areas within the Imperial College network with appropriate security controls implemented for data protection. Our data fields include postcode or address of residence which are held in an encrypted format with restricted access. The geographical information is essential for our small area analyses. This allows us to obtain an accurate link to UK administrative and census geography as well as other contextual information including environmental exposures and to accurately investigate diseases, health risks and detect disease clusters.

Our health data come from several data providers including NHS England, the Office for National Statistics (ONS), the Welsh Cancer Intelligence & Surveillance Unit (WCISU) and other national sources. These data holdings are refreshed on an annual basis or as required for specific studies.

Ethical and governance permissions to hold and use health data for environmental health research have been obtained from the following authorities:

• Health Research Authority - London South East Research Ethics Committee
• Health Research Authority - Confidentiality Advisory Group (CAG) advises on Regulations 5 of the Health Service (Control of Patient Information) Regulations 2002 to process patient identifiable information without consent
• The UK Health Security Agency (UKHSA) Caldicott Advisory Panel advises on Regulation 3 of the Health Service (Control of Patient Information) Regulations 2002 to process patient identifiable information without consent

SAHSU additionally holds small area data from the national Census on populations and socio-economic status (SES), including enumeration districts, census output areas, lower layer super output areas and wards (see Table of Social factor data). We also hold environmental data from several sources (see Table of Environmental data) including our research studies, the Environment Agency, Defra, the Civil Aviation Authority, the UK Health Security Agency, the British Geological Survey and water companies etc. (e.g. see our Environment and Health Atlas for England and Wales https://www.envhealthatlas.co.uk ). The maintenance of the databases (health, population, SES and selected environmental data) is conducted by the SAHSU database team.