Uncovering the end-of-life trajectories of older people with serious chronic illnesses: study protocol for the quantitative longitudinal study of the TRAJECT project.

Van den Bossche C, Tripathi K, Van den Block L, De Vleminck A, Decoster L, Naert E, Van Den Noortgate N, Pivodic L. Uncovering the end-of-life trajectories of older people with serious chronic illnesses: study protocol for the quantitative longitudinal study of the TRAJECT project. BMJ Open. 2026 Mar 30;16(3):e108617. doi: 10.1136/bmjopen-2025-108617.

Introduction: Older people who die with a serious chronic disease are at risk of experiencing extended periods (ie, months or years) of fluctuations and deterioration in their health and well-being. Traditional categorisations of these end-of-life trajectories focus on physical functioning and often consider three types (ie, cancer, organ failure, frailty/dementia), but data supporting these categories are limited, often neglect psychological, social and existential domains of health and well-being and provide little information on the extent and determinants of variation in end-of-life trajectories. 

This study aims to identify distinct temporal patterns in the trajectories of older people with serious chronic illness and determine to which extent personal, clinical and social characteristics predict them. 

Methods and analysis: We have developed and piloted a novel, feasible and acceptable study protocol for a longitudinal survey study with older people nearing the end of life. We will conduct a longitudinal survey study with 280 older people, aged 70 years or over, who have one or more chronic illnesses and who are in deteriorating health. Assessments will be done at baseline and every 2 months, over 12 months or shorter if the participant dies before. Deteriorating health is determined based on disease-specific criteria which we developed in collaboration with clinical specialists. People without cognitive capacity to consent to research participation, those in the terminal phase of life (ie, last days) and those who cannot participate in data collection in Dutch or French will be excluded. Participants will be recruited from hospitals in Belgium. The survey covers health and well-being in the physical, social, psychological and existential domains and determinants related to sociodemographic, clinical and social environment characteristics. When a participant dies, we will invite an adult proxy respondent (a family member or another close person) to complete a mortality follow-back study covering the deceased participants' health and care in the last 3 months of life. We will analyse trajectories with latent class growth models and mixed-effects models. Ethics and dissemination: The TRAJECT project has received approval from the Commissions for Medical Ethics from Universitair Ziekenhuis Brussel (Brussels University Hospital) and Ghent University Hospital. 

The findings of the study will be disseminated through scientific publications in international peer-reviewed journals and scientific conferences. For non-expert audiences, updates and findings will be shared through the project website, press releases and events for the general public. 

Keywords: Aged; Chronic Disease; Death; Longitudinal studies; Prospective studies; Retrospective Studies. 

© Author(s) (or their employer(s)) 2026. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ Group.