Friday October 2 2009
Life span continues to rise
“Most babies born in the past few years in the UK will live to be 100 if current trends continue,” The Guardian has today reported. The newspaper said that despite the elderly having more long-term illnesses, such as cancers and heart conditions, people will survive them because they will receive earlier diagnosis and better treatment.
The scientific review behind this story builds on a large body of ongoing research from the past five years. Its authors pose the question asked by policy makers about whether expected increases in life expectancy will be accompanied by a better quality of life. They believe that because aspects of the ageing processes have become more controllable, people are currently living longer without severe disability. However, whether these quality-of-life benefits will extend to future elderly generations remains uncertain.
One finding from this well-conducted research is that more than half of the babies born in developed countries since 2000 will potentially celebrate their 100th birthday. However, to predict what this will mean for the ageing population’s quality of life will need more study.
Where did the story come from?
This research was carried out by Professor Kaare Christensen from the Danish Ageing Research Centre at the University of Southern Denmark and colleagues from Germany. The study was supported by grants from the National Institutes of Health and of Ageing in the US, and published in the peer-reviewed medical journal The Lancet.
What kind of scientific study was this?
This was a systematic review of several pieces of previous research, which were then used to create a narrative report on predicted life expectancy and the rates of disease or disability (quality of life). The review section mainly included studies conducted since 2005. Mathematical modelling was included to predict the length and quality of life of people through to 2050 and beyond.
The researchers searched a variety of sources for information, including the International Network on Health Expectancies and Disability Process, the TRENDS network, and reports that were identified through published research databases such as PubMed. The researchers looked for reports published after 2005, also searching through their reference lists to find cited, older reports for inclusion if relevant.
To ensure the most recent demographic data was used, they extracted data from a source called the Human Mortality Database. The researchers present their findings in sections that cover mortality projections, trends in the complex notions of health, and issues of disease and disability.
What were the projections for mortality?
The researchers say the data on life expectancy from selected developed countries shows that between 1840 and 2007, life expectancy has lengthened almost consistently, with no sign of slowing down. Importantly, the researchers claim the data suggests that a limit to human lifespan is not yet near. The researchers also assess the probability of dying before the ages of 80 and 90 years, showing that this too had fallen between 1950 to 2003.
The predictions up until the year 2050 are based on German statistics and show increases in the proportion of elderly and retirement age groups compared to working and younger age groups. The calculations assume a constant total fertility rate of 1.4 babies per pregnant woman and a yearly net migration of 100,000 people. Life expectancy is predicted to reach 83.5 years for men, and 88 years for women by 2050.
What were the trends in health and disease?
The researchers explain that studies of health trends are complex due to a number of reasons. For example, the measures of disease or of any functional limitations or of disability are not consistent across the research. Also, the individual studies are not directly comparable as their designs or questions have also changed over time, and often the elderly in institutions are excluded from surveys despite the fact that they are an important group to study.
Despite these limitations, the researchers are able to say that there have been rises in many long-term diseases among the elderly including heart disease, arthritis and diabetes. In addition there have been increases in pain-related and psychological distress, general fatigue, dizziness, leg ulcers, heart problems, hypertension, asthma, osteoarthritis and lower back complaints.
In other reports, several diseases have decreased or improved: cardiac disease, asthma, osteoarthritis, depression and lower back complaints were found to be less in a Dutch study. The data was based on registers of activity and diagnoses from family doctors.
The researchers say that total cancer incidence has been rising, but deaths from heart attack have fallen more than rates of new heart disease. Obesity is also increasing.
What were the trends in disability?
The researchers analysed changes in disability over time using measures such as the restrictions in the ability to perform the activities of daily living and the need for assistance in daily life. These, they say, provide increasing evidence that the prevalence of disability has been falling since the 1980s and 1990s. Reductions in disability have been reported as fall of 0.4-2.7% every year.
What are the implications for a healthy and long life?
Health expectancies combine information about life expectancy and prevalence of good health. They can indicate if the period of disease or disability at the end of life is shortening or lengthening. Several measures can be used and results differ depending on which one is used (disease-free health expectancy, life expectancy in perceived good health, and disability-free life expectancy). While the trend has been improving for most measures, there has been a decrease for the most severe levels of disability at the same time as an increase for the least severe levels.
What interpretations did the researchers draw from these results?
The researchers conclude that people are living longer, but are not definite about whether this is accompanied by a better quality of life.
For people younger than 85 today, limitations and disabilities seem to occur later in life than in previous generations, despite an increase in chronic diseases and conditions.
The researchers explain this contradiction in four ways:
- There may be earlier diagnosis, improved treatment and better outcomes from prevalent diseases so that they are less disabling.
- An estimated 14-22% of the overall fall in disability can be attributed to reductions in disabilities associated with cardiovascular diseases. This has complicated the picture.
- The rising use of technology to help older people’s mobility, as well as improvements in housing standards and accessibility of buildings. might have made some diseases less of a functional limitation or disability.
- Finally, socioeconomic changes, such as increasing levels of educational attainment and income in elderly people and improved living and workplace conditions, might have contributed to the fall in disability.
The authors say that people younger than 85 today are living longer and are generally able to manage their own daily activities for longer than previous generations could.
What does the NHS Knowledge Service make of this study?
This is a complex and well-presented review, which has summarised a number of individual studies. The newspapers have focused on data on children that indicates that most born now will live beyond 100 years. While this may be true from the modelling contained in this report, the issue of how well they will be during their life still needs further research.
The researchers call for more research into this and discuss policy implications for matters such as retirement and the major challenges that healthcare systems will come to face. They say: “Very long lives are not the distant privilege of remote future generations - very long lives are the probable destiny of most people alive now in developed countries.”