The course of disability in the very old :drivers and trajectories

Abstract

In recent decades the rapid growth in the numbers of the very old, those aged 85 years and above, has made them the fastest growing age group of most populations worldwide. Nevertheless we know little about their health and disability, the latter being a particularly important aspect of quality of life for individuals but also more widely as a major determinant for residential care. This thesis uses a unique study, the Newcastle 85+ Study, a longitudinal, population based cohort study of people born in 1921 and aged 85 years at first interview in 2006, to explore the disablement process in very late life through three substantive sub-studies. In the first sub-study I explore how disability unfolds through the order of loss in basic and instrumental activities of daily living [(I)ADLs, these being the building blocks of disability. (I)ADLs were lost in a specific order, activities requiring long distance mobility and balance (for example shopping) being lost first and those requiring upper body strength (e.g. dressing, feeding) last and with little difference between men and women. The second sub-study examines the impact of specific diseases on disability onset and finds that arthritis, diabetes and cognitive impairment were similarly disabling for men and women, cardiac disease was more disabling in women, and cardiovascular disease and respiratory disease disabling for women only. The final sub-study uses novel statistical techniques to uncover patterns of disability from age 85 to 90. Four distinct trajectories of disability were found for both sexes, with a disability-free trajectory being identified in men but not women, and all other trajectories showing increasing levels of disability. These sub-studies are discussed in the light of other literature, the extent to which they explain the greater disability yet survival of women (the disability-survival paradox), and the implications for the future.