CRIS Data Linkages

NHS England (formally NHS Digital) are the data controller for the Hospital Episode Statistics (HES) and Office for National Statistics (ONS) Mortality data. HES contain details of all hospital admissions, outpatient appointments and A&E attendances at NHS hospitals in England. The ONS collects information on date and cause of death from death certificates. The data are collectively known as ‘mortality data’. Further details of the data held within HES and mortality data can be found on the NHS England website.

This linkage includes important clinical information such as diagnoses, operations or the speciality of the treating clinician; demographic information such as age, gender and ethnicity; as well as administrative data such as methods of admission and discharge. This linkage provides a resource for investigating physical health and cause-specific mortality in people with mental health problems.

The CDLS holds anonymised HES and mortality data on all South London and Maudsley NHS Foundation Trust (the Trust) service users who have attended hospitals anywhere in England. In addition, the CDLS also holds anonymised HES and mortality data on non-Trust service-user residents of the four London boroughs which form the Trust’s catchment area: Southwark, Lambeth, Lewisham and Croydon.

Comparing physical illness and mental health outcomes

This linkage enables researchers to compare physical illnesses and hospital use of Trust service users to the general population; this linkage also allows researchers to investigate risk factors for physical illness within patient groups or look at how pre-existing physical health problems may impact on the outcomes of mental health treatments. 

The linkage between CRIS and HES is important as the information on physical health gained from HES will allow policies and interventions to be developed and evaluated so that the care for people with mental disorders can be improved. 

Understanding lower life-expectancy

Previous research has found that people with mental disorders generally have a lower life expectancy than people without mental disorder, so the linkage between CRIS and ONS Mortality data is important as it helps researchers understand why this may be and provides information that will hopefully help in improving the life expectancy of individuals with mental disorders. 

De-identification

In order to link CRIS data with HES and mortality data, the CDLS send identifiable information for the Trust’s patients (NHS number, name, date of birth, and postcode) to NHS England. NHS England is able to use this information to link the individual records with hospital records from England. This linkage is legally permissible under the Health Research Authority’s support under Section 251 of the NHS Act 2006. This support enables temporary use of identifiers in a secure environment for accurate linkage. Once NHS England has linked the records, all personal information (NHS number, name, date of birth, and postcode) are destroyed and the linked records are supplied back to the CDLS. 

These data are fully anonymised prior to any researchers being given access to it. 

Data access

Data is hosted in the CDLS Trusted Research Environment (TRE) within the South London and Maudsley NHS Foundation Trust.  

All applications to use CRIS-HES and ONS Mortality data must be approved by the CRIS Oversight Committee. For more information on applying to use CRIS, see our Information for Researchers page.  

NHS Digital audit

In September 2021, the CDLS was audited by NHS Digital to ensure that the terms and conditions set for this linkage were being abided by and that data were being kept safe and secure.

Based on the audit, NHS Digital identified a number of areas of good practice and concluded that the overall risk of a breach of the terms and conditions with respect to compliance, duty of care, confidentiality or integrity was low. You can read the full audit report here.

Lambeth DataNet (LDN) is a healthcare database of GP records from practices within the London borough of Lambeth. Lambeth Together DataNet Steering Group are the data controllers of Lambeth DataNet, on behalf of Lambeth GP Practices. 

The CDLS has linked LDN to CRIS and currently hold anonymised LDN data for patients of the South London and Maudsley NHS Foundation Trust who are registered with a GP in Lambeth. The CDLS also holds anonymised LDN data for residents of Lambeth who are not Trust patients and this allows researchers to compare how mental disorders affect general health care, comparing people with and without a mental disorder. This data linkage provides a resource for investigating the physical health and health care of people with mental disorders with the aim of improving the care that they receive.

Data access 

Data is hosted in the CDLS Trusted Research Environment (TRE) within the South London and Maudsley NHS Foundation Trust. 

Applications to access the CRIS-LDN linked dataset must be approved by the CRIS Oversight Committee and the LDN Virtual Steering Committee. Approval from the LDN Virtual Steering Committee is dependent on locally agreed conditions (e.g. completion of a Privacy Impact Assessment (PIA), completion of a Common Application Form (CAF), and an agreement with the LDN team on costs - may vary with time). Final confirmation of approval for each project must be given in writing/email by the chair of the LDN Virtual Steering Committee to the CDLS. For further information, please contact the CRIS Team at cris.administrator@slam.nhs.uk.

The Department for Education (DfE) is the data controller for the National Pupil Database (NPD). The NPD contains detailed information about pupils in schools and colleges in England. The CDLS holds anonymised data from the NPD linked with the South London and Maudsley NHS Foundation Trust (the Trust) Child and Adolescent Mental Health Service (CAMHS), as well as an anonymised control sample of all school aged children, who are not Trust service-users, who were at school and lived in Croydon, Lambeth, Lewisham or Southwark from 2007 to 2019. This is the second linkage between CRIS and the NPD and a refresh of the original linkage which was completed in 2015. The NPD-CRIS linkage is the only UK dataset of its kind and will enable routinely collected educational and school census data to be used to understand childhood mental health issues.  

Exploring the relationship between education and mental health

This data linkage provides a resource for investigating the relationship between mental health and educational outcome. It will provide evidence to help families; treating clinicians and health policy makers understand the risk factors for childhood mental illnesses such as autism, attention deficit hyperactivity disorders, psychosis, obsessional compulsive disorders and depression. In addition, it will provide evidence to help clinicians and families understand the impact of childhood mental health on educational outcomes. 

This is an important objective for families who seek child and adolescent mental health care, to get their child back on track at school and improve their education performance; this linkage will enable research into how educational risks factors impact childhood mental health treatment and outcomes. 

Data access

The Office for National Statistics (ONS) are the data processors for this linkage and the data is stored within the ONS Secure Research Service (SRS), please see their website for more details.   

All applicants wishing to use the linked NPD data must become an ONS Accredited Researcher. Additionally, applications to use the CRIS-NPD linked dataset must be approved by the CRIS Oversight Committee, the DfE Data Sharing Approval Panel (DSAP) and the ONS’ Research Approval Panel (RAP). For further information, please contact the CRIS Team at cris.administrator@slam.nhs.uk. 

More information

Download the CRIS CAMHS Leaflet for more information.

King’s Health Partners (KHP) is an Academic Health Science Centre – a government initiative to bring universities and NHS Trusts together in closer working partnerships. KHP brings together King’s College London with South London and Maudsley NHS Foundation Trust (the Trust), Guy's and St Thomas' NHS Foundation Trust (GSTT), and King’s College Hospital NHS Foundation Trust (KCH). Information sharing is core to KHP – meaning that a doctor treating someone at GSTT is able to see that person’s Trust or KCH record, or a nurse at the Trust is able to access records at GSTT or KCH. 

Reflecting this information sharing by clinical teams, CRIS as an anonymised research database is also bringing together the information contained on different KHP services.  

Effects of COVID-19

Data linkage within KHP previously supported work into the effect of the COVID-19 pandemic on mental health services provided by the Trust. 

The COVID-19 pandemic placed unprecedented strains on all healthcare sectors. The Trust’s mental health services underwent radical changes which may have had profound effects on patient care and outcomes, as well as the potential risks that COVID-19 posed to populations already vulnerable to physical disorders. Data linkage between mental health data from the Trust and information on acute hospital attendances from KCH and GSTT enabled a series of studies which sought to describe and investigate these issues, responding as rapidly as possible to the needs of the Trust and both local and national priorities.

Renalware 

Renalware is a nephrology database system that was developed at KCH in 1996. It contains patient records for individuals cared for by the KCH Renal Unit including information on kidney disease, dialysis, and transplants. KCH is the data controller of the Renalware data.  

The Bridging the Gap Study

Previous research has demonstrated that chronic kidney disease is identified more commonly among patients with mental health difficulties than in the general population, even after controlling for risk factors such as the use of lithium-based medications, socio-economic status and smoking. Furthermore, while dialysis and renal transplantation are life-saving treatments, they are also demanding and impact appreciably on the everyday lives of end-stage kidney disease patients, often negatively affecting their emotional and psychological wellbeing. 

To address current gaps in our understanding of the link between kidney disease and mental health difficulties, the CDLS are planning to link health records data from CRIS with information from Renalware. This linkage will enable the study team to determine the prevalence of mental health difficulties in the kidney disease population and whether there are differences in health outcomes and access to healthcare between kidney patients with and without severe mental health difficulties such as schizophrenia or bipolar disorder. 

By undertaking this research, the study team aim to further understanding of kidney disease and mental health difficulties, to provide more effective long-term solutions and inform the management and support provided to kidney patients with severe mental health difficulties. 

Intersection of urological and pancreatic cancers and mental health

This linkage uses cancer data from GSTT and mental health data from CRIS to investigate the intersection of urological and pancreatic cancer types and mental health. The aim of this linkage is to quantify the mental wellbeing of urological/pancreatic cancer patients, define subgroups of patients with a urological or pancreatic cancer diagnosis who are more likely to develop a mental health disorder, and to quantify the impact of cancer diagnosis on existing mental health disorders. GSTT are the data controller of the urological and pancreatic cancer data.

Improving care provision for patients with severe mental illness in acute cardiac pathways  

This linkage uses cardiovascular data from KCH and GSTT and mental health data from CRIS. Many people with severe mental illness have physical health problems but may not get the treatments they need. While heart disease treatments have advanced, psychiatric patients have not experienced the same progress. Research is ongoing at KCH and GSTT to highlight these gaps in care provision, the results of which will inform future quality improvement measures. KCH and GSTT are the data controllers of the cardiac data from each respective organisation.  

Data access

Data is hosted in the CDLS Trusted Research Environment (TRE) within the South London and Maudsley NHS Foundation Trust.  

All applications to use the data must be approved by the CRIS Oversight Committee. For more information on applying to use CRIS, see our Information for Researchers page.  

The embryo, foetus and newborn child are very sensitive to external influences during development, for example the mother's health or lifestyle. External influences during these periods of development can have effects on the long-term physical and mental health of the mother and the child. For example, we know that if a mother has complications in pregnancy, that she herself may suffer from increased risk of ill-heath in later life, such as cardiovascular disease, diabetes or mental health problems.  

The eLIXIR programme aims to combine maternal, infant and child data into a single resource to allow information from large numbers of mothers and babies to be studied over a long period of time. The core datasets which make up the eLIXIR mother and baby cohort are maternity and neonatal data from Guy’s and St Thomas’ NHS Foundation Trust (GSTT) and King’s College Hospital NHS Foundation Trust (KCH). Each organisation remains the data controller of their own dataset.  

Understanding health in pregnancy

The aim of the eLIXIR project is to provide information about health in pregnancy and across the life span in a large number of people to help us work out when and how health problems begin, how we might prevent them and what treatments work in some people and not others. 

In England, mother, baby and child health records are kept in many different places and are not routinely linked to each other. eLIXIR will pull these data together and anonymise them for use in research. We will link health information from mothers and children, initially starting with local maternity and neonatal data and existing mental health data from the South London and Maudsley NHS Foundation Trust (the Trust). Later we plan to link with local primary care data, child clinical health data, national hospital and schools’ data.  

This new and important resource will help us explore the 'life course' of some of the most common diseases and help scientists and doctors to work out how we may prevent them. 

Areas where this research register will be used include:

1. Women’s health: including investigating relationships between pre-pregnancy physical and mental health, common disorders of pregnancy and pregnancy outcomes, and long term consequences of physical and mental health disorders in pregnancy for women;
2. Paediatrics: including the relationships between maternal physical and mental health disorders in pregnancy and adverse events and exposures in the fetal and neonatal period and their impact on long term physical and mental health outcomes for the child;
3. Mental Health: including the interrelationships between physical and mental health disorders during pregnancy and pregnancy outcomes, and relationships between maternal and childhood mental health;
4. Implementation Science and Public Health: including the evaluation of new pathways of care/guideline recommendations to improve maternal and or child physical and/or mental health.

Data access

Data is hosted in the CDLS Trusted Research Environment (TRE) within the South London and Maudsley NHS Foundation Trust.  

All applications to use eLIXIR data must be approved by the eLIXIR Oversight Committee.

More information

More information can be found on the eLIXIR website.

The Office for National Statistics (ONS) are the data controllers of the 2011 census data. The census is a national survey which takes place every 10 years in England and Wales on a nominated day. Every effort is made to include all people resident in England and Wales on that day and ask them questions about their housing, social, health, and living circumstances. Individuals are also asked about their ethnicity, country of birth, and citizenship. The most recent census was conducted in 2021, and previous census surveys were conducted in 2001 and 2011. The ONS has linked CRIS to 2011 census data; this linkage is the first between NHS mental health records and census data in England.  

This data linkage provides a resource for investigating the impact of social and demographic factors, such as employment, migration status, and poverty, on mental health treatment and outcomes. The linkage is being used to examine the social determinants of onset, course and outcomes of severe mental health problems, and is being done through the ESRC-funded Social and Economic Predictors of severe Mental Disorders (SEP-MD) study led by Dr Jayati Das-Munshi. Results from research using this linkage will be fed back to relevant organisations with the aim of directly impacting patient care and informing changes to NHS policies. 

The Big Ideas is the SEP-MD study's podcast series, exploring how data shapes our understanding of health and inequalities and how to make the collection and use of data more inclusive to inspire a more equitable future. 

Data access

The Data is hosted within the ONS’ Secure Research Service. The data processor for this CRIS linkage are the ONS.   

All applicants wishing to use the CRIS-ONS dataset must become ONS Accredited Researchers. Additionally, applications to use the CRIS-ONS dataset must be approved by the CRIS Oversight Committee. For information about access to the dataset, please contact Dr Jayati Das-Munshi at jayati.das-munshi@kcl.ac.uk 

A previous data linkage between CRIS and local cancer records (through the Thames Cancer Registry) provided a resource for investigating the relationship between mental health and cancer. The link brought together information on cancer diagnoses, clinical features of the tumour, data from the first three months of intervention, and place and date of death up to 2009. 

Cancer and mental health

Through this linkage, a series of analyses were performed to investigate cancer incidence among people with mental disorders, mortality rates after cancer diagnosis, and cancer treatments received in order to inform better treatment strategies. 

This initial analysis found no evidence that cancer presentations are delayed in people with mental disorders, as the spread of the cancer at diagnosis was not different between people with or without mental illness. However, despite this, a lower survival rate after cancer diagnosis was still found in people with severe mental disorders, suggesting that research should focus on the care received after diagnosis. 

Therefore, a new data linkage has now been set up which brings together information from CRIS with cancer records, Hospital Episode Statistics (HES), and mortality records from the National Cancer Registration and Analysis Service (NCRAS). 

NHS England are the data controllers of the NCRAS data. The NCRAS collects information about every patient diagnosed with a malignant tumour in England in order to support public health, service monitoring, and research. The NCRAS collects information on over 300,000 cases of cancer every year, including detailed data about the type of cancer, how advanced it is, and the treatment the patient receives. The CDLS have linked CRIS to cancer data from the NCRAS along with information on hospital visits from HES, and mortality data. 

Improving cancer detection and care

The CDLS holds anonymised cancer data on all South London and Maudsley NHS Foundation Trust (the Trust) service users who have received a diagnosis of cancer anywhere in England. In addition, the CDLS also holds anonymised cancer data for non-service-user residents of the four London boroughs which form the Trust’s catchment area; Southwark, Lambeth, Lewisham and Croydon. 

This will enable us to investigate in more detail the care received by people with mental disorders after a cancer diagnosis and the outcomes people experience, in order to investigate whether differences in these might explain differences in cancer survival. By generating information on improving cancer detection and care for people with mental illness in the UK, this project aims to enhance mental healthcare among cancer patients - whether or not they have an existing mental disorder, and improve the quality of end-of-life care for people with comorbid cancer and mental disorders. 

Data access

Data is hosted in the CDLS Trusted Research Environment (TRE) within the South London and Maudsley NHS Foundation Trust.  

All applications to use CRIS-NCRS data must be approved by the CRIS Oversight Committee. For more information on applying to use CRIS, see our Information for Researchers page.  

The Child and Family Court Advisory and Support Service (CAFCASS) represent children in family court cases in England. They operate within the law set by Parliament (Criminal Justice and Court Services Act 2000) and under the rules and directions of the family courts, and they are independent of the courts, social services, education and health authorities and all similar agencies. It is CAFCASS’s duty to safeguard and promote the welfare of children going through the family justice system.

CAFCASS collect data on family court cases that they are involved in, including:

• the number of cases where the court has asked CAFCASS to carry out work in private law cases;
• the number of care order applications made by local authorities;
• the length of time taken to complete care and supervision proceedings;
• and the rate of care order applications by local authorities.

CAFCASS are the data controllers of this data. 

Understand the mental health needs of mothers

CRIS has been linked with CAFCASS data to enable researchers to understand the mental health needs of mothers involved in care proceedings (family court cases where the council applies to have a child removed from parental care due to serious concern over their health or wellbeing).

Mothers whose children are placed into public care or adoption often have high levels of health needs, such as drug and/or alcohol misuse, exposure to violence, mental health problems as well as chronic physical conditions. However, information is lacking on how health services address these needs. This linkage will enable researchers to determine the needs of mothers before, during and after care proceedings by using longitudinal data on mental health service use.

Data access

Data is hosted in the CDLS Trusted Research Environment (TRE) within the South London and Maudsley NHS Foundation Trust.  

All applications to use CRIS-CAFCASS data must be approved by the CRIS Oversight Committee and the CAFCASS Research Advisory Committee. 

The Department for Work and Pensions (DWP) is responsible for welfare, pensions, and child maintenance policy within the UK; they collect information on a range of different key state benefits, for example Employment and Support Allowance (ESA), Permanent Injury Benefits (PIB), and Job Seekers Allowance (JSA).

The CDLS has linked CRIS to data from the DWP; this linkage includes important anonymised information on benefits received, as well as details of any programmes attended, such as work support schemes. The DWP are the data controllers of the benefits and employment data.  

Studying mental health policies

This linkage is the first between NHS health records and DWP data. The main purpose of this project is to examine the effect of welfare reform and current assessment policies on mental health recovery and relapse: this would include examining the impact of potentially positive events (engagement in a work support packages) and negative events (regular work capability assessment, benefit sanctions, and the reduction or removal benefits) on a patient’s mental health. 

The linkage between CRIS and the DWP is important because a large percentage of adults seek psychiatric help for symptoms which impact heavily on their ability to work. 

Understanding patients’ benefit and occupational needs is essential to ensuring that people with mental disorders receive the best possible care. This linkage will help to provide high quality research outputs that examine the interface between mental health, work and welfare. Ultimately, this will provide much needed evidence to direct occupational health and welfare policy initiatives. 

Results will be fed back to relevant organisations such as the Department of Health and the DWP, and promoted locally with the aim of directly impacting patient care, through informing changes to NHS and government benefit policies. 

Data access

Data is hosted in the CDLS Trusted Research Environment (TRE) within the South London and Maudsley NHS Foundation Trust.  

All applications to use CRIS-DWP data must be approved by the CRIS Oversight Committee and by the Work and Health Screening Panel (WAHSP). For further information, please contact the CRIS Team at cris.administrator@slam.nhs.uk.   

The HIV and AIDS reporting system (HARS) was developed by Public Health England (PHE), now UK Health Security Agency (UKHSA), in conjunction with the Department of Health and the Clinical Reference Group for HIV. The UKHSA are the data controllers for the HARS data. 

All outpatient HIV service providers submit data to HARS on a quarterly basis. HARS contains clinical data on all people diagnosed with HIV in England and this information is used to monitor the quality of care provided to people with HIV, support the commissioning of HIV services, and increase the efficiency and quality of HIV monitoring.

The CDLS has linked HARS to CRIS and currently hold anonymised HARS data for patients of the South London and Maudsley NHS Foundation Trust. This data linkage provides a resource for investigating the health care of people with HIV and mental disorders, with the aim of improving the care that they receive.

HIV and severe mental illness

HIV in people with severe mental illness (SMI) is an incredibly under-researched area in the UK, therefore, research is needed to examine the prevalence of HIV in people with SMI, the identification of at risk groups, parity in treatment and testing compared to the general population, and clinical challenges (e.g. adherence to medication).

Linking mental health data from CRIS with information on HIV from HARS will allow us to answer questions about risk and clinical picture both in terms of HIV status and mental health status. This work has the potential to highlight areas of need in treatment and prevention of HIV in people with SMI.

Findings of the research will be fed back to relevant organisations such as NICE and promoted locally with the aim of directly impacting NHS policies and current patient care.

Data access

Data is hosted in the CDLS Trusted Research Environment (TRE) within the South London and Maudsley NHS Foundation Trust.  

All applications to use CRIS-HES and ONS Mortality data must be approved by the CRIS Oversight Committee. For more information on applying to use CRIS, see our Information for Researchers page.  

More information

Download the CRIS-HARS Leaflet or Poster for more information.

By law, fertility clinics have a duty to submit data to the Human Fertilisation and Embryology Authority (HFEA) about fertility treatments taking place and babies born as a result. The HFEA are the data controllers of this data which is held on a secure database and is the longest running database of its kind in the world. This register collects data on more than 75,000 treatments that take place in UK fertility clinics each year. 

The CDLS has linked the HFEA database to CRIS and currently holds anonymised HFEA data for female patients of the South London and Maudsley NHS Foundation Trust (the Trust) who have also undergone fertility treatment within the UK. 

We believe it will be the first undertaking of its kind to demonstrate the use of routinely collected mental health and fertility treatment data in order to understand the two-way relationships between infertility/fertility treatments and the treatment/outcome of mental health disorders. 

By undertaking this linkage, and subsequent research projects, it will provide a strong evidence-base to improve understanding of people’s risks and experiences, informing service improvement, and guiding targeted intervention to improve outcomes and experiences of women undertaking fertility treatments. 

Data access

Data is hosted in the CDLS Trusted Research Environment (TRE) within the South London and Maudsley NHS Foundation Trust.  

All applications to use CRIS-HFEA data must be approved by the CRIS Oversight Committee and by the HFEA Register Research Panel.