The emergence of the frail older adult: mixed trends and potential explanations

Dorly J. H. Deeg, Vrije Universiteit Amsterdam

A good understanding of recent trends in morbidity and disability is paramount to forecasting and perhaps influencing future trends. However, explanations of trends so far have been based on declines in disability as have been observed to date in the United States and some other developed countries. Observations of declining trends lead to different explanations than observations of increasing trends. In this contribution, explanations for the mixed trends observed in the Netherlands are sought. Based on published literature and empirical data from a historic and a recent study in the Netherlands, trends are examined in morbidity, mild and severe disability and self-rated health across five decades. Potential explanatory factors are derived from additional analyses. The prevalence of chronic conditions rose since the mid-1950’s. Whereas severe disability showed a decreasing trend, mild disability increased. Self-rated health showed a decreasing trend until the 1990’s, which stabilized after that. Although explanatory factors that have been proposed in the USA (rising level of education, advances in medical treatment, increased use of assistive devices, and greater increases in male than female life expectancy) have followed the same development in the Netherlands, these factors cannot serve as explanations for increasing trends. Empirical evidence supports alternative explanations: changes in the associations between diseases, mild disability, and self-rated health; changes in the functioning of the health care system, in particular shorter hospital stays; differences in trends between socio-demographic subgroups of the older population, with worse trends in the less-well-off; and recent boosts in the public image of old age. The explanations provided for the mixed trends observed in the Netherlands may prove useful for anticipating on future trends in other countries. If the underlying evidence is replicated in research elsewhere, this will allow better planning of health care capacities.