The ageing population
The demographic structure of the Swedish population, and its dynamics, have been in focus among scientists and politicians on several occasions during the previous century. It is currently a prioritized issue because of the rapid increase in the number and percentage of old and very old people. This will have a big impact on society through increased demands on the health care system and through consequences for social security systems, including retirement age. A drastic reduction in the number of births in combination with a continuous reduction in mortality has led to the present – and will determine the future – population structure.
Mortality can be followed in Sweden for over 250 years. Over that period, life expectancy has increased from 40 to 80 years, by an average of 2 months per year. This trend continues to date. Reduction in childhood mortality explains most of this change during the early period, but there have been reductions over the entire age span. During the last decades, primarily improvements in mortality above the age of 65 drive the increase in life expectancy. Currently, mortality reduction among the old and very old attracts considerable interest. Is it reasonable to assume that the mortality reduction will continue or is it approaching an end? A commonly held view is that the survival curve is becoming increasingly rectangular since more and more people survive to an age closer to maximum life span. If this was true, the increase in life expectancy would gradually slow down as it approaches the maximum life span. However, this hypothesis is not supported by data which show that life expectancy (in the record keeping countries) continues to increase almost linearly with no indications of leveling off. At the same time, we have seen that the mortality risks among the oldest old in Sweden and Denmark have not improved the past decades. The risk of dying after turning 100 is the same today as it was 40 years ago. Also the maximum age of death has not improved the past decade. Directly linked to this are questions about determinants of longevity. These questions are addressed from several different angles including molecular genetics using telomere length as a biomarker of ageing and of course by close scrutiny of mortality patterns. Doll and Peto discussed this in a BMJ paper in 1997 postulating that there is no such thing as ageing, but only a lifelong accumulation of risk factors.
A core question when discussion the prolonged life is whether the increase in life expectancy is driven by declining disease rates or by improved survival from disease. This will have an impact on population health. Even if both parts contribute, it seems like survival has improved more than the incidence of diseases has declined, which will result in an increasing share of the population with a history of disease. Another important aspect of this research is whether the extended lifespan has been characterized by healthy or unhealthy years. It’s an easy question to phrase but a difficult question to answer because of the many different definitions and measurements of poor vs good health.
In addition to how health has changed among the old, the structure of health- and elderly care has changed dramatically in Sweden the past decades. Hospital stays have become shorter, waiting times in some instances longer, and a shift from living in institutions to living at home with home care has taken place the past two decades (1). Today, the majority of old people, in Sweden as well as in other countries, live at home with home care or assistance, rather than in institutions. The research about home care is sparse. Even if the granting of home care rely on the decision of an administrative official, it is of interest to investigate the distribution of home care based on variables such as household composition, marital status, childlessness and socioeconomic status.
The research area of ageing and longevity, its determinants and consequences is of major societal importance and at the heart of public health sciences. It is an area that links public health, epidemiology and demography. Sweden has unique data for research along these lines because of a very long history of health and mortality records and excellent current mortality data along with other relevant information.
Aims of project
The overall objective of this research program is to increase the knowledge about ageing processes of human populations, the development of healthy life expectancy in relation to total life expectancy, and potential implications for society. It will ultimately contribute to informing and preparing policy makers to face the 5th epidemiological transition currently taking place.
With a unique database consisting of the total Swedish population over several decades, together with a highly competent and interdisciplinary team, the combined resources will enable novel approaches and bring the research front about the health of the ageing population forward.
The research program is built around three themes.
Theme 1. Human longevity
We have found that in parallel with increasing life expectancy, mortality has become more compressed in the population, that is; the variability in age at death in the population has become smaller. We will continue to explore this, together with the potential for additional mortality compression. Other questions to be covered are the lack of mortality improvements at the highest ages and whether or not we are approaching a limit to human life. And, whether the rate with which mortality increases with age is a force we cannot defeat.
Theme 2. Ageing and health
Whether the prolonged life is a consequence of improved health or improved survival with disease is an often-phrased question within ageing research. Despite numerous studies there is still no consensus. Less informative prevalence studies dominate the literature together with studies looking at changes in age of disease onset. We take a more ambitious approach by not only focusing on disease onset, but the whole chain of disease events. We focus on the most dominant diseases in old age such as myocardial infarction, stroke and hip fractures, and study changes in risk of disease onset, subsequent events, as well as changes in survival, and how they interrelate.
Theme 3. Societal consequences
The societal implications of an ageing population are a topic of concern in all ageing societies. In this theme we focus on disease burden, future living arrangements and care of elderly, potential support deficits of old persons, and the role of family support for health and survival in old age.
The studies are primarily based on Swedish national register data of the total population.
The project is planned to continue at least to 2021.