Irish Longitudinal Study On Ageing (TILDA)

The Irish Longitudinal Study on Ageing (TILDA) is a major inter-institutional initiative led by Trinity College Dublin (TCD) which aims to produce a massive improvement in the quantity and quality of data, research and information relating to older people and ageing in Ireland. It involves detailed interviews on a two yearly basis with a cohort of people aged 50 and over, charting their health, social and economic circumstances over a 10-year period. The study aims to determine: (1) the health, social and economic status and needs of older people, (2) the biological and environmental components of "successful ageing", (3) the contributions that older people are making to society, and (4) how each of these key components interact and inform public health and social policy ensuring that Ireland meets the needs and choices of its citizens.

Data Collection
Wave 1 of TILDA was collected in 2010 and is a representative cohort of over 8,500 people resident in the Republic of Ireland aged 50 years and over. Households were selected in geographic clusters from a list of all residential addresses in Ireland. Each selected household was visited by an interviewer and residents aged 50 or older, as well as their spouses or partners, were invited to participate. The household response rate was 62.0%. Each respondent provided written informed consent. Those with cognitive impairments that prevented meaningful consent being given, were not included in the study. Respondents were interviewed in their homes by trained professional interviewers on many aspects of health, lifestyle, social interactions, and financial circumstances. They were also asked to answer a self-completion questionnaire. Each respondent was then invited to travel to one of two health centers, in Dublin and Cork, for a comprehensive health assessment or received a home health assessment. The sampling procedure, the home interview, and the health assessments have all been described in detail (Kearney et al., 2011a; Kearney et al., 2011b).

Wave 2 of TILDA was collected in 2012 and included approx. 7,300 respondents, a response rate of 86%. Once again respondents were interviewed in their homes and self-completed a questionnaire. This wave did not include a comprehensive health assessment. The next health assessment will take place at Wave 3, which was undertaken in 2014. An overview of the longitudinal study design and sample numbers is provided in Figure 1.

The collection of TILDA biomarkers was taken during the comprehensive health assessments at Wave 1 and a reduced subset was taken during the home interview at Wave 2.

Additional samples were collected in Waves 3 of the study (2014). Lipid profiles were obtained at Wave 1 and carotenoid analyses on banked plasma samples has been undertaken by the Vision group lead by Prof. Stephen Beatty and Dr. John Nolan at Waterford Institute of Technology (WIT). In Wave 3 (2014), the aim was to expand on the types of samples that would be banked for future study.

The biomarkers collected to date are outlined in Table 1. TILDA has been designed such that many biomarkers map onto similar international studies of older adults such as the Health and Retirement Study (HRS), the Survey of Health, Ageing and Retirement in Europe (SHARE) and the English Longitudinal Study of Ageing (ELSA). In addition, a set of "TILDA-unique" biomarkers were also measured (Table 1).


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