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Linking your data

The ELSA Research team consist of several collaborators; University College London (UCL), Institute for Fiscal Studies (IFS), University of Manchester (UoM), and the National Centre for Social Research (NatCen). NatCen, as the lead organisation, will be the only organisation with access to fields that can be used to identify you. Because the ELSA Research team researchers at UCL, IFS, and UoM do not hold any identifiable information about you. NatCen, whose interviewers conduct the ELSA interviews with you, is responsible for working with NHS England to get the data securely linked, and will be the only organisation with access to fields that can be used to identify you.

The data linkage journey

This is how the process works:

If you agree to data linkage you will be asked to provide a few pieces of information during the interview that can be used to identify your records, like your name, address, date of birth and National Insurance number and National Health Service Number.

NatCen separate these details from your other answers and pass them over to the government department or organisation who hold your records. Provided you’ve given consent these details will be sent to:


  • NHS England to be linked to your Hospital Episode Statistics, mortality data including broad cause of death, (supplied by NHS England on behalf of the Office for National Statistics) and cancer data (supplied by NHS England on behalf of Public Health England). We will send your ELSA member ID, NHS Number, Date of Birth, postcode and gender in order for NHS England to trace and link this data about you.

  • HM Revenue and Customs to be linked to National Insurance Records.

  • The Department of Work and Pensions to be linked to administrative records on receipt of state benefits.


NatCen link the data they receive from NHS England, HM Revenue and Customs and the Department of Work and Pensions to your survey answers using the ELSA member ID number to create a new set of data which contains no directly identifiable data. This de-identified linked dataset is shared with researchers at UCL, IFS and UoM. This will include all the useful information from your survey answers linked to the administrative data - but no one at UCL, IFS, and UoM will know it’s about you.


If any other researchers wish to access the de-identified data for a specific purpose, they need to seek permission from the ELSA Research Team using a separate application process, as well as an agreement from NHS England (the national controllers of health data). We would also like to make some basic information about the current status of ELSA cohort members available to researchers, including death registration data including broad cause of death, to enable analyses of life trajectories and life expectancy.

Why the linked data are needed

Hospital Episode Statistics

Although NatCen collect information about your health during the interview, there is not enough time to collect detailed information about your use of health services. The Hospital Episode Statistics contain records of all admissions, outpatient appointments and accident and emergency attendances at NHS hospitals in England. By linking your information to these records the ELSA researchers will be able to analyse the data to improve our understanding of how and why the use of hospital services varies among the over 50s. Because you tell us about your health, we can try to isolate the difference in hospital use over and above any differences in health and other characteristics across different people. This will enable us to provide evidence on how well spending on health and social care is allocated across different types of people and to look at inequalities in quality of care. The data will also be used to assess the impact that stays in hospital may have on other important aspects that affect your quality of life.

Mortality data

ELSA is a study about ageing and how the ageing process varies across different types of people. In order to understand what happens to people in later life, it’s important that we know when they have died and how they have died. Linking to mortality records gives us accurate information on cause and date of death. Mortality data is sourced from civil registration data.

Cancer data

Cancer Registration data is collected by Public Health England. These data contain information about the type of cancer or condition and any treatment that you may have.

Linking your information to these records we will be able to analyse the data to improve our understanding about who is affected by cancer, inequality in cancer care and how having cancer impacts on other aspects of your life.

Benefits data

The UK system of state benefits is complex, and we recognise that it is difficult for you to accurately tell us how much income you are receiving from different sources and how long you’ve been receiving them. Linking the information that you give us with administrative data gives us additional information about your income sources over a long period of time (all of which could not be collected as part of a survey). There is concern that some people who may be entitled to benefits may not be claiming them and we would like to understand why. Combining information on your circumstances with accurate information on which benefits you may be receiving allows us to analyse which factors may be affecting take-up. The data will also be used to look at policy issues relating to benefits. For example, we are able to see what happens when the government introduces a new benefit or changes an existing benefit.

National Insurance Records

Administrative data from National Insurance records provides a historical picture of your income and a detailed historical picture of your contributions to the National Insurance system. Although we collect information on your current income in the interview, it is important to understand the way that your income may have changed over your lifetime and how this has affected your current circumstances. Understanding your contribution to the National Insurance system allows us to calculate how much you could be entitled to receive from the State Pension. Knowing this means that we can look at how this may affect how long you continue to work, how much you save in other forms and what the impact may be on other aspects of your life such as your health.

How long we keep your data

We would like to keep the data at our institution as long as we have live projects that use the data, or there is the possibility of future projects that will use the data.

We will ensure that your records are secure for as long as we continue this study.

How to opt in or out 

The first time you take part in ELSA, you will be asked to provide consent for us to link to each of the types of data listed above. You can choose to consent to all of them, or some of them, or none of them. For each type of link, you will be provided with information to read, which explains the type of data that is collected, the purpose that it is collected for, how we control access to this information, and how to withdraw your consent if you change your mind. 

After that first time, you will be asked at each interview whether you still consent to each type of link.

You can withdraw your consent to any one or all of the different types of data. You can also withdraw your consent at any time outside of the interview by:

  • Writing to us at NatCen, Kings House, 101-135 Kings Road, Brentwood, Essex CM14 4LX or

  • Emailing


Please tell us which health records you no longer wish to consent to link; information to allow us to correctly identify you in our records (your name and DOB and/or the reference on the permission form originally left with you); and an address, email address or telephone number in case we need any further information to complete your request.

If you have any questions about this process, please call us on NatCen Freephone 0800 652 4574.

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