The Northern Ireland Cohort for the Longitudinal Study of Ageing (NICOLA) is a large-scale, public health study involving a representative sample of men and women aged 50 years and over living in Northern Ireland.

The primary objective of NICOLA is to collect longitudinal multidisciplinary data across a wide range of domains to be used for investigation and research relevant to ageing and making Northern Ireland a better place to grow old in.

NICOLA collects extensive information on all aspects of health, social and economic circumstances of ~8500 men and women as they grow older in Northern Ireland over a series of data collection waves approximately every 2-3 years.

Longer term research goals will investigate the determinants of retirement behaviour and economic wellbeing, the impact of cognitive function and sensory disability on decision making, the determinants of disability trajectories, the influence of social participation on these and the interaction of genetic, biological and psychosocial determinants on health and mortality.

There has been one sweep of data collection (2013 – 2016) and a second is currently underway (2017 – )

The Northern Ireland Longitudinal Study (NILS) is a large-scale, representative data-linkage study created by linking data from the Northern Ireland Health Card Registration system to the 1981, 1991, 2001 and 2011 Census returns and to administrative data from other sources. These include vital events registered with the General Register Office for Northern Ireland (such as births, deaths and marriages) and the Health Card registration system migration events data. The result is a 30 year plus longitudinal data set which is regularly being updated. In addition to this rich resource there is also the potential to link further Heath and Social care data in our distinct linkage projects (DLPs).

Selection into the study is based on birth date (day and month): 104 dates throughout the year were selected and if an individual’s date of birth coincided with one of these they were included in the sample. The sample is large – c. 28% of the Northern Ireland population (approximately 500,000 individuals and accounting for approximately 50% of households).

The Northern Ireland Mortality Study (NIMS) is a large-scale data linkage study that links the 1991, 2001 and 2011 Census returns for the whole of the enumerated population (approximately 1.6 million individuals) to subsequently registered mortality data from the General Register Office (GRO). While larger than NILS it is more limited in scope, focusing only on the linkage of mortality data. It allows researchers to focus on more detailed analyses of specific cause of death, some of which may not be possible in NILS because of small numbers in sub-populations and the analysis of less common causes of death (e.g. accidental death). The NIMS dataset is recommended to researchers whose primary interest is in mortality in Northern Ireland. These data are maintained under the same conditions as the NILS and is accessible only under the same constraints.