"How do I feel today?" An analysis of HRQOL variability among Institutionalized older adults

Intra-individual variability is a central topic in Nonlinear Dynamical Systems (NDS) studies of human development, because the theory predicts that particular forms or properties of intra-individual variability will serve as indicators or predictors of transitions, bifurcations, and stable states in individual development. Currently, there are almost no studies that address intra-individual changes and variability of Health Related Quality of Life in old age. The main aim of this paper is to analyze the role of day-to-day HRQOL variability and long term HRQOL and disability development in a sample of institutionalized older adults. 22 older adults took part in this longitudinal study. Daily diary-based assessments were made for a period of 100 days. Furthermore, monthly assessments of HRQOL and disability with validated questionnaires were performed. The intra individual variability on a day-to-day basis was found to be related to HRQOL and disability development. Furthermore, life events as operationalized by extreme values in HRQOL were related to the level of day-to-day HRQOL variability. As predicted by NDS theory, day-to-day variability emerges as an important indicator of levels of and changes in HRQOL and disability and as such, it may be an important indicator of developmental processes in old age.