How well are we aging? : capturing the complexity of health trajectories of older adults

Abstract: Despite its positive nature, population aging represents a public health challenge that could be alleviated by maintaining good health during older age. The aim of this thesis was to evaluate how well people are aging, taking the complexity of their health status into account. All four studies included data from the Swedish National Study on Aging and Care in Kungsholmen (SNAC-K). Study I also gathered data from the Kungsholmen Project (KP). The reference population consisted of the people living in the community or in an institution in Stockholm, Sweden. In the KP, they were aged 75+ in 1987, and in SNAC-K, aged 60+ between 2001 and 2004. Study I. Between 1991 and 2010, both prevalence and incidence of disability remained steady with a tendency towards a gradual decline. In this period, survival increased in functionally independent people but remained constant in disabled people. Our findings suggest that we are living longer and healthier lives, at least in urban-dwelling non-impoverished societies with access to adequate health care and public health assistance. Study II. We used four health indicators to characterize the health status of a population of adults aged 60+ living in Stockholm, Sweden: morbidity, physical impairment, cognitive impairment, and mild and severe disabilities. While multimorbidity and slow gait speed were already prevalent (>60% and >20%) among sexagenarians, both cognitive impairment and mild disability were low until age 84, and severe disability was nearly absent until 90. Study III. The four health measures used in Study II were integrated in a health assessment tool (HAT) for assessing and following health changes in older adults. The HAT score ranges from 0-10 (poor-good health). HAT was reliable over time and accurately predicted adverse health outcomes (ROC area hospitalization: 0.78, 95% CI 0.74–0.81; mortality: 0.85, 95% CI 0.83–0.87). At baseline and follow-ups, at least 90% of participants aged 85 or younger were free of severe disability, and half were functionally independent despite some morbidity. Study IV. A HAT score higher than the age-/sex-specific median was related to completion of the chair-stand test (OR: 2.6, 95% CI 2.1–3.3), better balance and grip test results (interaction OR: 1.2, 95% CI 1.1–1.3), and good self-rated health (OR: 2.2, 95% CI 1.8–2.7). HAT predicted social and medical care use better than did disability (p<0.001) and morbidity (HAT better for hospital admission, formal care, and informal care; p<0.001). HAT score can be computed with a flowchart, and the percentile curves help estimate individual health status. Conclusions. The health status of this urban Swedish population was fairly good. Time trends in disability remained stable over 20 years (1991-2010), and at the same time, the increase in life expectancy during recent years appeared to be driven by the longer lives of functionally independent people. Studying the health status of older people using multiple indicators of health, we found that age 80-85 is a transitional period when major health changes take place, often following the co-occurrence of more than one negative health event. HAT, composed of relatively few items, may help assess and identify deviations from expected health trajectories at the individual level and determine medical, rehabilitation, or social care needs at the population level. Determination of individual-level deviations can be facilitated by creating reference health curves similar to the growth charts used by pediatricians. HAT is a reliable and valid health measure and is a good candidate for use in developing such geriatric health charts.