Northern Ireland Cohort for the Longitudinal Study of Ageing

It is predicted that 1 in 4 children born in Northern Ireland today will celebrate their 100th birthday. While this trend is good news, by 2048 almost half of the population will be aged over 50 years, thus posing many challenges for our society and policy makers.

NICOLA is the first large scale longitudinal study of ageing to be set up in Northern Ireland. It aims to explore why and how certain social, economic and biological factors are changing the lives of older people, to understand how health, lifestyle, financial circumstances and wellbeing change with age and to understand what it is like to grow older in Ireland.

The study has recruited 8,500 people in private households from across Northern Ireland to provide a true representation of the Northern Ireland population and has been designed to maximise comparability with other well-established international longitudinal studies, in particular the Health and Retirement Survey in the United States (HRS), the English Longitudinal Survey of Ageing (ELSA) and The Irish Longitudinal Study on Ageing (TILDA).

Wave 1 of the study which was conducted between December 2013 and March 2016 had three main components: a Computer-Assisted Personal Interview (CAPI) conducted in the participant’s home; a self-completion questionnaire (SCQ) including a dietary questionnaire; and an objective health assessment. Data collection for Wave 2 took place between May 2017 and November 2019 and consisted of a CAPI only.

The CAPI covers pensions, employment, living standards, health aspects including service needs and usage, as well as social contact and formal and informal care. The self-completed questionnaire covers relationship quality, loneliness, stressful and traumatic life events, worry and alcohol intake.
The health assessment included a range of measurements including height, weight, blood pressure, cognitive function, cardiovascular function, gait and balance tests, respiratory function and visual health. Blood and urine samples were also obtained as part of the health assessment. Following completion of the health assessment, participants were asked to complete a 130-item food frequency questionnaire that assessed their food and drink intake over the previous 12-month period.

The detail of information collected to date allows us to investigate trajectories of ageing and their social and biological determinants and consequences, underscoring its value for policy makers, the research community and wider economy.

A further add-on to Wave 2 has been the mailing of a self-completion COVID questionnaire to all study participants in February 2021. This specific questionnaire was designed to capture information relating to physical and mental health, food provision, financial security, work and finances, volunteering and caring, health and lifestyle, social connections, pensions and retirement during the period of COVID-19. The questionnaire content is closely harmonised with that of ELSA to facilitate comparative analysis. The data obtained will enable us to make pre- and post-COVID comparisons as well as global comparisons in relation to the impact of COVID-19 on the health and wellbeing of older adults.

Sample design

Participants were originally sources from a randomised sample of NI addresses which were obtained from the Business Service Organization (BSO) General Practitioner Register Database. Addresses were identified using a systematic approach and stratified by geographical location and postcode to ensure a nationally representative sample.

Over 400,000 addresses were initially identified as having a household member aged 50 years or above. From these addresses, a smaller random sample, based on over 14,000 addresses, was selected to provide an overall representation of the Northern Ireland population. Selected addresses were visited by an interviewer from Ipsos MORI. All persons aged 50 years or over (and their spouses/partners of any age) were canvassed to participate in the survey.

A nationally representative sample of over 8,500 adults, aged 50 years and over and resident in Northern Ireland, were selected using this population sift.

Sample boosts

The NICOLA sample was refreshed for Wave 2 in order to maintain the representation of individuals aged 50 – 54 years.

Linked data

The NICOLA cohort is flagged on the National Health Applications Infrastructure Service (NHAIS) to enable robust and comprehensive linkage for identification of participant outcomes and affecting factors.

In March 2021, NICOLA also became one of many UK longitudinal research studies contributing to a national research partnership called the UK Longitudinal Linkage Collaboration (UK LLC) which is embedded within the COVID-19 Longitudinal Health and Wellbeing National Core Study. The UK LLC has been designed to allow large population based studies such as NICOLA to fully contribute to the national research programme and policy development in response to the COVID-19 pandemic. It brings together data from UK based longitudinal studies and manages the linkage and integration of data to routine health and administrative records, thus providing greater breadth and depth of data and enabling researchers to answer priority research questions to help inform government policy and healthcare decisions.

Management and funding

Led by the Centre for Public Health at Queen’s University Belfast (QUB).

NICOLA is supported by a range of funders. To date, these have included:

Accessing the data

Approved researchers, and others from the practitioner and policy communities who wish to use the anonymised dataset can do so by making an application using the designated proforma available on the NICOLA website.

Cohort profile

Neville C.E., Cruise S.M., Burns F. (2019) The Northern Ireland Cohort for the Longitudinal Study of Ageing (NICOLA). In: Gu D., Dupre M. (eds) Encyclopedia of Gerontology and Population Aging. Springer, Cham.