METHOD ARTICLE Linking death registration and survey data: Procedures and cohort profile for The Irish Longitudinal Study on Ageing [version 1; peer review: 2 approved, 1 approved with reservations] Mark Ward 1 , Peter May 2 , Robert Briggs 1,3 , Triona McNicholas 1,3 , Charles Normand 2 , Rose Anne Kenny 1,3 , Anne Nolan 1,4 1 The Irish Longitudinal Study on Ageing, Trinity College Dublin, Dublin, Ireland 2 Centre for Health Policy and Management, Trinity College Dublin, Dublin, Ireland 3 Department of Medical Gerontology, St James's Hospital, Dublin, Ireland 4 The Economic and Social Research Institute, Dublin, Ireland First published: 08 Jul 2020, 3:43 https://doi.org/10.12688/hrbopenres.13083.1 Latest published: 19 Nov 2020, 3:43 https://doi.org/10.12688/hrbopenres.13083.2 v1 Abstract Background: Research on mortality at the population level has been severely restricted by an absence of linked death registration and survey data in Ireland. We describe the steps taken to link death registration information with survey data from a nationally representative prospective study of community-dwelling older adults. We also provide a profile of decedents among this cohort and compare mortality rates to population-level mortality data. Finally, we compare the utility of analysing underlying versus contributory causes of death. Methods: Death records were obtained for 779 (90.3% of all confirmed deaths at that time) and linked to individual level survey data from The Irish Longitudinal Study on Ageing (TILDA). Results: Overall, 9.1% of participants died during the nine-year follow- up period and the average age at death was 75.3 years. Neoplasms were identified as the underlying cause of death for 37.0%; 32.9% of deaths were attributable to diseases of the circulatory system; 14.4% due to diseases of the respiratory system; while the remaining 15.8% of deaths occurred due to all other causes. Mortality rates among younger TILDA participants closely aligned with those observed in the population but TILDA mortality rates were slightly lower in the older age groups. Contributory cause of death provides similar estimates as underlying cause when we examined the association between smoking and all-cause and cause-specific mortality. Conclusions: This new data infrastructure provides many opportunities to contribute to our understanding of the social, Open Peer Review Reviewer Status Invited Reviewers 1 2 3 version 2 (revision) 19 Nov 2020 report report version 1 08 Jul 2020 report report report Dan Lewer , University College London, London, UK 1. Peter Harteloh, Statistics Netherlands (CBS), The Hague, The Netherlands 2. Zubair Kabir, University College Cork, Cork, Ireland 3. Any reports and responses or comments on the article can be found at the end of the article. HRB Open Research Page 1 of 52 HRB Open Research 2020, 3:43 Last updated: 11 DEC 2020