What do we know about human lifespan with regard to the length or shortness of life? The information to be had is small, observation careless and tradition based on fables.
—Francis Bacon, Historia Vitae et Mortis, 1645
Longevity in the future will alter both the practice of medicine generally and cardiovascular disease in particular. Fig 1⇓, the curve of human survival by Gompertz, was first described in 1825 in the Philosophical Transactions of the Royal Society of London. It illustrates ideal human survival unaltered by any disease process. The inner curve at 1900 and the middle curve at 1990 show the change in mean survival in this century. Both infant mortality and diseases of mid-life have drastically changed, resulting in a longer lifespan and as a result many older people in our society.
Life expectancy in the United States in 1900 was 47 years, with 4% of the population older than 65. In 1996 life expectancy is 76 years, with 12.3% of the population over 65. By 2026 life expectancy will be a mean of 82 years, with 20% of the population over 65. Aging is therefore a social phenomenon of the 20th century with profound medical and social implications. The rapid increase is more than either predicted or expected and is still not generally appreciated. In the United States, more than 30 million people are older than 65 years. The aged now constitute 12% of our population but use one third of the drugs and account for roughly one third of the healthcare costs. Forty-five percent of those treated have cardiovascular disease. There are also major social implications. In the over-75-years age group, there are approximately 185 women to each 100 men; at 85, the ratio is 3 to 1. One in 10 persons over 65 has a child living who is also over 65 years.
Much of our future society will depend on the interplay between aging, lifestyle, and disease. For too long, however, we have been influenced by mortality rates and life expectancy. In the future we must concentrate on both illness and disability in the living.
Fig 2⇓ shows the female population of Japan, the oldest in the world.1 These data, obtained from vital statistics and population surveys, show a gradient from disability to morbidity to mortality at various ages in terms of health loss relative to age. These data, which are more crucial to healthcare planning than mortality, are not readily available.
Fig 3⇓ shows the decline in coronary heart disease (CHD) mortality in Australia between 1950 and 1994.2 In Australia, as in most Western countries, there has been an impressive decline in CHD mortality similar to the United States. This has been hailed variously as a triumph of public health care, medical therapy, or primary prevention. The important question is whether the actual number of patients with CHD has decreased when the increase in the elderly population is accounted for.
Fig 4⇓ compares the total population in Australia in 1950 and in 1994.3 The data are for three age groups: those aged 55 to 64, those aged 65 to 74, and those older than 75. The total population is in millions of people. The 55-to-64 age group has doubled, the 65-to-74 age group has tripled, and the over-75 age group has quadrupled, illustrating the disproportional increase in the aging population. These demographic changes are used to compare the mortality rate with the actual number of deaths from coronary artery disease (CAD) between 1950 and 1994.
Fig 5⇓ illustrates the total population, male and female. In 1950 the mortality rate was almost twice that of 1994. The number of deaths in the 55-to-64 age group has decreased significantly despite a doubling of the population in that group, whereas deaths have increased in the 65-to-74 age group and more than doubled in those over 75.
In the male population, Fig 6⇓ shows the same trends as in Fig 5⇑. The female population, illustrated by Fig 7⇓, shows fewer deaths in the 55-to-64 and 65-to-74 age groups, with a halving of the mortality rate between 1950 and 1994; however, the number of deaths in the over-75-years group has increased threefold despite a substantial reduction in mortality rate due to a huge increase in the over-75 female population.
Fig 8⇓ compares the 1950 and 1994 deaths in persons aged 35 to 85+ years. The number of deaths decreases in middle age despite doubling of the population but is significantly greater in the over-65-through-80 age group.
Fig 9⇓ shows the total number of deaths since 1950 every 10 years and in 1993 and 1994. Overall they have increased 60%, despite a 60% reduction in CHD, and are predicted to increase further in the future.
Fig 10⇓ illustrates that 80% of CAD deaths now are in the aged. This fact needs to be emphasized. Many trials have excluded elderly patients, notably the long-standing Monica trials, which seem hardly representative of the disease under study when 80% of patients are excluded.
Fig 11⇓ also shows the decreasing reduction in mortality with age between 1950 and 1994, with decreases of nearly 65% in the 45-to-54 age group and 40% in the over-75 age group. The observation that CHD is reduced in all age groups but less among the older is obviously relevant in preventive strategies but has not been taken into account in most trials.
The main points to be emphasized from these data are that most of the statistics displayed by governments and heart foundations showing the impressive decline in mortality concentrate on the under-65- or -70-years age groups, a legacy from the past, when old age was thought to be irrelevant. We as cardiologists have accepted this, even smugly, taking some credit for this impressive change. This has been our mistake. As cardiologists we have been politically in error, because this mortality decline is translated by politicians and the media into phrases such as “The battle for heart disease has been won!” This in turn is reflected in decreased funding for both research and management of cardiovascular disease.
Fig 12⇓ shows 1994 figures of US research spending in dollars per death. A high-profile disorder like AIDS attracts 38 times the funding for research that heart disease does. Funding of diabetes research is five times that for heart disease and funding for cancer research four times more. It is important in the future that the total burden of heart disease be presented to politically redress this imbalance.
What about our future society? Fig 13⇓ shows the population of Australia from infancy to old age3 : there are 18 million people. The pyramidal shape reflects a high-fertility, high-mortality society. Note, however, the larger 1995 population compared with the 1970 population aged 35 to 50 years. This large difference represents the “Baby Boomer” population, which began at the end of the Second World War. This large group of people is aging, moving upward on the graph. With the attendant low birth rate at the bottom, the graph will convert to a rectangular shape illustrating the aging of the society. When this group reaches age 65, beginning in the next millennium, a huge increase in cardiovascular disease is expected.
Fig 14⇓ shows percent actual and projected growth from 1996 to 2041. Note there is no growth in the population younger than 45 years and substantial increase in the population over 65 years in about 2010, which continues to 2040.
Fig 15⇓ shows the estimated incremental change now with the rapid growth of the aged over 65 and over 75, beginning in 2010, peaking at 2030, and declining afterward.
The same process is happening in all countries, except in some African nations, but at varying rates. Population aging is the term used to describe the number of years to double the over-65-years population.4 Table 1⇓ shows that population aging occurs much more rapidly in developing countries than in the developed countries where it has already occurred. In Sweden 18% of the population is over 65. China shows the most rapid growth of aging, increasing from 7% to 14% in 27 years. Because of China’s very large population, the figures are staggering. By 2020, China will have 200 million aged people, 40 million over 85, more than the population of most nations.5
In Brazil, over a 70-year period beginning in 1950, the total population will increase three times, the over-65 population 15 times. This emphasizes that developing countries have a more rapidly growing aged population than the developed nations and with less health resources to meet the obvious demand. This is not all. Within the general population of the aged, the 85+ group is showing a phenomenal increase. These people are known as the old and now constitute 22% of the aged, a figure that will rise to 35% in 30 years.6
The 85+ population in the United States in 1970 was 1 million people; now that population is about 3.3 million. In 30 years those 85 and older will number between 16 and 23 million, or 5% of the population. This age group has a prevalence of heart failure of 10% to 15% and CAD of 30% and will further increase the demands of health care.
One quarter of those attaining the age of 65 now will live to be older than 90. Thus a very old person, an object of exotic curiosity a generation ago, is no longer so. This is a worldwide phenomenon. Nine countries in the world have more than 1 million old, and in 30 years there will be 19 countries with that many old.
If these projected demographic figures for the aged are used with the known current incidence of CAD, hypertension, and heart failure, the approximate numbers of such patients that will need appropriate treatment in the future in the older age groups may be calculated and an attempt made to quantify the clinical burden of disease.
Coronary Artery Disease
Data from the Australian Heart Foundation show the increasing prevalence of coronary disease within the three deciles from 9.4% at age 55 to 64 to 18.1% at 75+ years. Figs 16A⇓ and 16B⇓ show the prevalence of CAD and the projected numbers of people with ischemic heart disease in the aged, both 65 to 75 years and 75+ years in 1996, 2016, and 2026. The incidence, determined by population surveys in Australia in 1989,2 probably underestimates the incidence in older age groups as the longitudinal study in Gothenburg, Sweden,7 suggests: the incidence of ischemic heart disease in the aged is 30% and would significantly increase.
The incidence of hypertension is high in the older age groups, greater than 30%. Fig 17A⇓ shows the Australian Heart Foundation prevalence data2 and Fig 17B⇓ the projected numbers in 1996, 2016, and 2026. There will be a twofold increase in the number of patients who need to be treated for hypertension.
As treatment has been shown to prevent both stroke and coronary artery events in systemic hypertension and isolated systolic hypertension in the elderly,8 for the pharmaceutical industry this represents a potential therapeutic bonanza of major dimensions.
Despite the protestations that there are too many physicians and cardiologists in the community, who will treat these people?
What about heart failure? Fig 18⇓ shows figures from the Framingham study in the United States.9 When Australian data from 1950 and 1993 are compared (Fig 19⇓), the number of patients with heart failure increased dramatically in all age groups, but by more than 500% in the 85+ years age group.
Fig 20⇓ shows the projected numbers of aged patients with heart failure in 1996, 2016 and 2026. Because heart failure requires expensive medical treatment and is the most common cause of medical admission to public hospitals, this represents an ever-increasing demand on healthcare budgets.
Fig 21⇓10 shows that in a comparison of treatment of cardiomyopathy in the early 1980s and the early 1990s, the outcome was almost doubled over the latter five-year period. This is ascribed to medical treatment and can only improve in the years that lie ahead. Paradoxically this will make the problem of heart failure even more prevalent and more expensive in our future society.
Medical interventions and surgical therapies continue to improve. However, this will add to the social and economic costs in our aging society. This therapeutic triumph may be our economic Armageddon.
In conclusion, our future global society is an aging society. Aging is a social phenomenon of this and the next century, with important health implications for cardiovascular disease. Population aging is occurring more rapidly in developing countries. For most of this century a primary aim of medical endeavor has been to decrease mortality. Perhaps as we approach the next millennium, we should concentrate on preventing disability and enhancing enjoyment of life in our ever-increasing aging population.
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Presented at the 69th Scientific Sessions of the American Heart Association, November 11, 1996, New Orleans, La.
- Copyright © 1997 by American Heart Association
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