The importance of knowing life expectancy

Predicting life expectancy is far from an exact science. Statistical modeling may be mathematically precise, but assumptions are far more subjective. A 2009 study confidently stated that most babies born in the U.S. and Western Europe today should live to 100. Another group of scientists predicts life expectancy at birth will be 100 years by 2060, based on current trends. A more modest projection by the United Nations arrived at the same figure by the year 2300.

On the other hand, an influential article in the New England Journal of Medicine estimated that the effect of obesity could trim as much as five years of life by the middle of this century.

Other research echoes this. Researchers used a forecasting method that accounts for the delayed effects of accumulated health risks among younger adults. The results suggested the effects of rising obesity on future life expectancy and health-care costs could be far worse than currently anticipated.

Projecting life expectancy is much more than an academic exercise. If it is underestimated by just one year, that would mean an extra 53 million years lived by Americans 65 and older between 2000 and 2050. That would have enormous implications for Medicare and Social Security costs.

If life expectancy continues to grow and disease is kept at bay, life stages – education, work, retirement – will continue to be blurred.  Young people are taking longer to complete higher education because of steeply rising costs and dim career prospects. Meanwhile, the elderly are delaying retirement because of eroded stock portfolios, the security of health-insurance benefits in the workplace or self-fulfillment – especially if they are in robust health.

One trend is clear: The world is going gray. The number of people 65 and older will double to 1.3 billion globally by 2040. The elderly will outnumber children under age 5 for the first time in history.

At this point, there is no technology to extend the human lifespan. Dr. Nortin Hadler, in his book Worried Sick: A Prescription for Health in an Overtreated America, contends that the best we can hope for is 85 disease-free years – at which point life’s warranty expires. Any time beyond that is a bonus. He argues that medicine has little impact on longevity because it saves the lives of only a small percentage of the population.

Fearing disability more than death

A long life is one thing. A healthy life free of disease and disability is another. The evidence suggests that life overall is lengthening, but that disease and disability may be increasing. The result: More months and years spent in poor health. It has been dubbed a “failure of success.”

It is also a failure of “compression of morbidity,” a concept developed by Stanford professor James Fries 30 years ago. He believed the same forces that lengthened life expectancy would also decrease – or compress – the number of years of disease and disability prior to death. In other words, the ideal healthy life would be one spent without impaired functioning right up until the moment of death.

People over 50 generally do not fear death as much as disability. When questioned, they express a dread of potential chronic illness, pain and immobility. They fear senility, loss of memory and dependence on others.

Disease trends are mixed. People are acquiring chronic disease at earlier ages, but disability generally is being delayed because of medical technology. For example, a 20-year-old today can expect to live one less healthy year than a 20-year-old did a decade ago – even though life expectancy has grown. A typical 20-year-old man today can expect to spend nearly six years of his life without basic mobility, two more years than a decade ago. For a 20-year-old woman, it will be nearly 10 years of being unable to walk up 10 steps or sit for two hours.

Despite medical progress, the age of a first heart attack has remained relatively constant since the 1960s and the incidence of several forms of cancer continued to increase until recently. High cholesterol and high blood pressure have decreased only because of successful pharmaceutical treatments.

These trends certainly shatter the illusion that each successive generation would live longer and healthier lives. It also does not bode well for the extra burden placed on age-based entitlement programs such as Medicare and Social Security.

Physical decline is not inevitable. Fries and his colleagues followed more than 400 people for 12 years and categorized them based on lifestyle risk factors: cigarette smoking; physical inactivity, and being under- or overweight. Those with no risk factors had almost no disability 10 to 12 years before death, and the incidence of disability rose slowly until the end. Those with two or more risk factors had more disability, which rose significantly 18 months before death. Those with moderate risk declined swiftly three months before death.

Disability can be delayed relatively late in life by lifestyle choices. Mental and physical facilities can be improved at any age. It has been called the “plasticity of aging,” a phenomenon that can significantly diminish the effects of aging. This plasticity is why some 80-year-olds can run marathons and 90-year-olds can substantially increase strength by weightlifting. Age-related decline in maximum athletic performance is only 1 percent a year beginning at age 25. Training to achieve one’s athletic potential is far more important than one’s age. The body tends to rust out rather than wear out. Several studies show that improving one’s lifestyle and health behaviors reduces late-life disability more than it lengthens life expectancy — thus decreasing the amount of time spent with illness.

The rate of disability has been declining steadily since the early 1980s, although it is unclear why. It could be a number of factors: declining smoking rates; assistive medical devices; rising educational levels, and improved cardiovascular treatment. However, obesity may reverse that trend. Researchers estimate disability will begin to increase 1 percent a year by 2020 because of the excess weight carried by people 50 to 70 years old – and that’s assuming they gain no more weight.

The four leading causes of premature death

The four leading causes of premature death: smoking, high blood pressure, elevated blood glucose and being overweight or obese, according to a Harvard School of Public Health study. Those factors reduced life expectancy about five years for men and four years for women.

The researchers created eight demographic groups they called “Eight Americas.” The Eight Americas were defined by race, county, region and socioeconomic features to demonstrate the impact of health disparities. The Eight Americas were Asian-Americans; Northland low-income rural whites; middle American whites; low-income whites in Appalachia and the Mississippi Valley; Western Native Americans; middle American blacks; high-risk blacks and Southern low-income rural blacks.

For example, Southern rural black men lost almost seven years of life because of the risk factors, compared with less than four years for Asian-American women. Blacks, especially those in the rural South, had the highest blood pressure. Native Americans and Southern black women were the most obese. Native Americans and low-income whites smoked the most.

Health disparities exist on every health measure in the U.S. However, they are particularly pronounced in life expectancy. For example, a black man living in Washington, D.C., on average will die 17 years sooner than a white man in adjacent Montgomery County, Md.

Ralph Keeney, a Duke University professor, bluntly declares that nearly half the people who die before age 65 have only themselves to blame.  The list of poor decisions is a familiar one: smoking; binge drinking; overeating; not exercising; unprotected sex; not wearing a seat belt; using drugs; suicide and homicide. By comparison, only 5 percent of deaths in 1900 and 25 percent in 1950 were self-inflicted.

Nearly one-quarter of American women and one-third of American men die before age 75 of causes that potentially could have been prevented by timely and effective health care. They either chose not to seek care or could not afford it. The U.S. ranked 15th out of 19 industrialized nations on regular use of health-care facilities. If the U.S. had performed as well as the top three nations – France, Japan and Australia – it would have averted more than 100,000 deaths a year.

In 1975, Americans who reached 50 years old could expect to live slightly longer than Europeans did. By 2005, the U.S. had fallen significantly behind Europe in life expectancy, primarily because of chronic disease among the near-elderly. Americans are twice as likely to have high blood pressure, be obese or have diabetes. Economists calculated that the U.S. could save up to $1.1 trillion by 2050 if its health status were comparable to that of its peers.

A Health Affairs study measured survival rates in 12 other industrialized nations and compared them with national health-care costs. In 1975, the U.S. was close to the average per-capita cost and ranked last. By 2005, health-care costs had tripled and were twice as much per capita than any other nation – and the U.S. still ranked last. This was despite the fact that smoking decreased more rapidly and obesity grew more slowly than in other nations.

What controls health and premature death

Medical care gets too much credit for prolonging life.

A 2002 Health Affairs journal article calculated the contribution of factors that determined health and premature death. Those influences were personal behavior, life circumstances, environmental toxins,  medical care and genes.

Behavior accounts for 40 percent of premature deaths. The leading causes in this category are smoking, obesity and physical inactivity. While Americans place great faith in medical technology to extend life, simple changes in health habits would have far more impact.

Life circumstances cause 15 percent of premature death, but may contribute significantly to the other factors. People with lower income, less education and lower social status die sooner and are more likely to be disabled. People in lower classes are more likely to have poor health behavior: They smoke more, and have riskier lifestyles.

Environmental exposures account for 5 percent of premature deaths. Occupational products, pollution, lead paint and chemical contaminants are unpleasant facts in dangerous jobs and substandard living conditions.

Medical care affects only 10 percent of premature deaths, yet it accounts for 95 percent of U.S.  health-care spending. The big contributors in this category are lack of access and medical errors, which the Institute of Medicine estimates kill as many as 98,000 people annually. Lack of health insurance, which affects 16 percent of the U.S. population, also contributes to premature death.

Genes, which are considered an uncontrollable factor, cause 30 percent of premature deaths. Yet genetic predisposition is not destiny. About two-thirds of obesity risk is genetic, but the condition does not happen without poor health habits. Dr. David Heber, director of the UCLA Center for Human Nutrition, points out that the human DNA changes 0.5 percent every million years but the obesity epidemic is only about 30 years old.