NHS admin data now linked to Millennium Cohort Study

News, Data release
7 December 2022

Researchers tracking the experiences of young people born at the turn of the century can now explore a wider range of research questions related to health care and treatment in hospitals, thanks to a new data linkage between NHS Digital and the Millennium Cohort Study (MCS).

This new linked dataset, complementing the health linkages that have already been enacted for the older three cohorts at the UCL Centre for Longitudinal Studies (CLS), will allow researchers to explore a range of health-related issues across four generations.

The linked administrative and survey data, available via the UK Data Service SecureLab, will open up new opportunities for researchers to investigate the factors that affect health, and the way health interacts with other facets of people’s lives.

The datasets contain information about all hospital admissions in England including accident and emergency attendance, critical care, inpatient and outpatient appointments. Spanning the period 2001-2020, they provide details on diagnosis, types of therapies, treatment length and other clinical information.

With the consent of cohort members, the Hospital Episode Statistics (HES) data have been linked to their longitudinal survey data. The survey data, collected since birth, cover topics such as physical health, mental health and wellbeing, health behaviours, education, work, finances and family.

CLS, which manages MCS, and NHS Digital adhered to strict data security protocols to protect cohort members’ identities when linking the HES data to the MCS records. A total of 6,027 cohort members were successfully matched to their HES records.

Professor Emla Fitzsimons, Principal Investigator for MCS, said: “I am thrilled that researchers now have the opportunity to access linked NHS Hospital Episode Statistics and Millennium Cohort Study data. These new linked datasets hold great promise for improving our understanding of the lives of young people and the health issues facing this generation.”

The linked health datasets have been de-identified and can be accessed by registered researchers through the UK Data Service SecureLab, which enables the data to be widely used by accredited researchers.

Additional bespoke access arrangements, which include an additional NHS data sharing agreement and data minimisation via the selection of variables, have been put in place to ensure that this secure onward sharing complies with NHS Digital requirements.

Linked health datasets have already been linked to the three other cohort studies at CLS: the 1958 National Child Development Study (NCDS), the 1970 British Cohort Study and Next Steps.


How to access the data

The linked data are available via the UK Data Service’s secure access system, the SecureLab. Information about how users can apply for access to these data can be found on the UK Data Service website.

The datasets are included in the UK Data Service catalogue: Millennium Cohort Study: Linked Health Administrative Datasets (Hospital Episode Statistics), England, 2000-2019: Secure Access


Find out more

More information on the linked data datasets is available in the user guide: Millennium Cohort Study Linked Health Administrative Datasets Hospital Episode Statistics (HES): User Guide



  1. CLS securely transferred personal details (such as the cohort member’s name, sex, date of birth and address) when working with NHS Digital to link the health data to the survey data. No other information about the person was sent, or any of their answers to the surveys. NHS Digital only used these details to identify the person in their systems and to send CLS their health records. Once the correct information was identified, these personal data were destroyed. All linked data are made available to researchers under a secure access licence. Names, addresses, National Insurance and/or NHS numbers, are never disclosed.
  2. Highly confidential datasets managed by the UK Data Service are classified as controlled data, which are not available under standard UK Data Service access arrangements. Users applying for controlled data have additional conditions of access, including the completion of special forms and attending a training course. Once approval is granted, datasets are available to view on the UK Data Service’s secure system, the Secure Lab. Data accessed in this way cannot be downloaded. Once researchers and their projects are approved, they can analyse the data remotely from their organisational desktop, or by using the UK Data Service’s Safe Room. They provide access to statistical and office software to make remote analysis and collaboration secure and convenient.

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