A review in this week’s edition of The Lancet discusses the challenges of an aging population. If current life expectancy trends continue, more than half of babies born in rich nations today will live to 100 years. Not only are we living longer, but those added years are spent with less disability and fewer limitations on daily life than in the past. In addition, preliminary evidence suggests shortened working weeks over extended working lives might further extend increases in life expectancy and health. The review is the work of Professor Kaare Christensen, of the Danish Ageing Research Centre, University of Southern Denmark, Denmark, and colleagues.

During the 20th century, enormous increases in life expectancy of more than 30 years have been seen in most developed countries. Death rates in nations with the longest life-expectancy, such as Japan, Sweden, Spain suggest that, even if health conditions do not improve, three-quarters of babies will live to see their 75th birthdays. If life expectancy continues to improve at the same rate, most babies born in rich nations since 2000 can expect to live to 100 years. Consequently, disease and disability rates in old age will have an increasing effect on the sustainability of modern society. The increases in life expectancy in rich countries, apparent since 1840, show no signs of slowing.

The authors explain: “The linear increase in record life expectancy for more than 165 years does not suggest a looming limit to human lifespan. If life expectancy were approaching a limit, some deceleration of progress would probably occur. Continued progress in the longest living populations suggests that we are not close to a limit, and further rise in life expectancy seems likely.”

In rich nations, mortality in people older than 80 years is still declining. According to data from more than thirty developed countries, in 1950 the probability of survival from age 80 to 90 years was on average 15 to 16 percent for women and 12 percent for men. In 2002, these values were 37 percent and 25 percent. Since the death rates of children and young adults are very low in these nations, additional increases in life expectancy will be achieved through further improvements in the oldest age groups.

The authors use Germany as a case study. They demonstrate how the German population will be significantly older and smaller than it is now, in 2050. This prediction is as well representative of other developed nations.

Due to more people living longer, overall cancer incidence is rising. Other chronic diseases such as diabetes and arthritis are also rising. Cardiovascular disease prevalence is also increasing. This is attributed to the fact that cardiovascular mortality is decreasing. As a result more people are alive with it since less are dying from it, in any particular age group. The answer to quality of life in old age is functional ability, and how it affects the activities of daily living (ADL). The activities that are central to self-care are called basic ADL. They are:

• bathing or showering
• continence
• dressing
• feeding
• transferring from bed and chair

Disability in instrumental ADL refers to disabilities affecting a broad range of activities such as:

• doing laundry
• handling drugs
• housekeeping
• managing finances
• preparation of food
• shopping
• telephone use
• using transport

After measuring these indicators, there is increasing evidence suggesting that disability prevalence has been declining.

A common indicator of disability-free life expectancy is being developed by the European Health Expectancy Monitoring Unit. It is named healthy life years (HLY). Time trends are available for 14 European countries between 1995 and 2003. Individuals who answer to the European Community Household Panel question “Are you hampered in your daily activities by any physical or mental health problem, illness or disability?” by “moderate” or “severe”, are defined as disabled. On the basis of this measure, differences in HLY in European countries are large, even among countries with similar yearly rates of increase in life expectancy.
Some countries show a rise:
• For men: Austria, Belgium, Italy, Finland, and Germany.
• For women: Belgium, Italy and Sweden.

Some countries show stagnation:
• For men: France, Greece, Ireland, and Spain.
• For women: Austria, Denmark, UK, Finland, France, Spain, and UK.

Some countries show reduction:
• For men: Denmark, Portugal, Netherlands, Sweden, and UK.
• For women: Germany, Greece, Ireland, Netherlands, and Portugal.

This is estimated in the proportion of years spent disability-free at ages 65 years and older. Inequalities in HLY are even greater if all 25 countries of the EU are considered.

A series of studies has reported larger improvements in disability-free life expectancy than in life expectancy. A comparison of four health surveys in France concludes that gains in life expectancy over recent decades might have added years with moderate difficulties but not years with severe difficulties. This finding is corroborated by German and Belgian research. The authors explain: “Continued improvement of health trajectories depends on improvement in elderly people, although the foundation for this progress might partly be based on enhanced living conditions and lifestyle early in life. Progress towards improvement of health is likely to depend on public health efforts to – for example, combat smoking, obesity, low levels of exercise, poor diets, and excess drinking, and to provide improved living conditions and care for elderly people with several ailments.”

The issue is whether we are not only living longer, but also better. For people younger than 85 years, most of the evidence suggests a postponement of limitations and disabilities. This is despite an increase in chronic diseases and conditions. This apparent contradiction is at least partly accounted for by early diagnosis, improved treatment, and amelioration of prevalent diseases so that they are less disabling. People younger than 85 years are living longer. Generally, they are capable to manage their daily activities for longer than were previous cohorts.

The situation is not as obvious for people aged older than 85 years. There is little information. Also, there is widespread concern that exceptional longevity has grim results both for individuals and for societies. The authors debate on the “common view in clinical medicine and among some gerontologists that the substantial rise in proportion of exceptionally long-lived individuals in successive birth cohorts is the result of help given to an increasing proportion of frail and ill people into advanced old age, with huge personal and societal costs.”

According to Danish research, the proportion of independent individuals is similar in those aged 100 to those aged 92 to 93 years. Consequently, the fact that more people live longer puts a greater burden on society as a whole. But exceptional longevity does not mean exceptional levels of disability. However, it is the overall financial burden of aging populations that is causing most concern to developed nations. The old-age dependency ratio is the number of people aged over 65 years divided by those of working ages (15 to 64 years). In Germany, for every 100 people aged 15 to 64 years, the number aged 65 and over has gone from 16 in 1956 to 29 in 2006, and is expected to reach 60 by 2056.

The authors recommend a redistribution of employment as a possible strategy to cope with the economic implications of aging. They remark: “If people in their 60s and early 70s worked much more than they do nowadays, then most people could work fewer hours per week than is currently common – if they worked correspondingly more years of their longer lives. …Preliminary evidence suggests that shortened working weeks over extended working lives might further contribute to increases in life expectancy and health. Redistribution of work will, however, not be sufficient to meet the coming challenges. Even if the health of individuals at any particular age improves, there could be an increased total burden if the number of individuals at that age rises sufficiently.”

They write in conclusion: “Increasing numbers of people at old and very old ages will pose major challenges for health-care systems. Present evidence, however, suggests that people are not only living longer than they did previously, but also they are living longer, with less disability and fewer functional limitations.”

“Ageing populations: the challenges ahead”
Kaare Christensen, Gabriele Doblhammer, Roland Rau, James W Vaupel
Lancet 2009; 374: 1196-208
The Lancet

Written by Stephanie Brunner (B.A.)