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July 10, 2006

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elderly couple walking
Men and women who make it to age 75 in 2006 can expect to still be around in 2016 and 2017, respectively. At age 85, the odds are good that you'll reach 91.

The longer you live, the longer you can expect to live

Quiz measures death risk

By William J. Cromie
Harvard News Office

If you were born in the United States and celebrate your 65th birthday this year, you can expect to be around for your 81st birthday if you are male, and for your 84th if you are female.

Life expectancy in this country has been rising steeply since 1990, and the National Center for Heath Statistics concludes that the older you are today, the greater the age you are likely to reach. Men and women who make it to age 75 in 2006 can expect to still be around in 2016 and 2017, respectively. At age 85, the odds are good that you'll reach 91.

Newborn boys should survive until about age 75 and girls to age 80, according to numbers published by the National Center for Health Statistics. That works out to a life expectancy of 77.6 years for people in the United States, up from 75.4 years in 1990.

How come people who have already reached these ages can expect to keep going for 10 or 15 more years? Because they have already dodged the mortal dangers that do in younger people: infant mortality, violence, and auto wrecks, according to the July issue of the Harvard Health Letter, published by the Harvard Medical School. The article also credits the survivor effect. People with good genes who have lived in beneficial surroundings - good nature and nurture - are overrepresented in older populations.

life expectancy chart

What's more, people who study aging trends believe that life expectancies for the old will continue to grow longer. The main reason is that the three biggest killers of older people - heart disease, cancer, and stroke — are being treated more successfully.

You can't really cheer too loud about living longer if you're also living sicker. But there's also good news about staying healthy. Vincent Mor at Brown University Medical School comes up with three reasons. First, more than ever, older people can drive or have access to transportation, and their homes are more friendly to aging. There are fewer stairs, and bathrooms can be modified for easier use, for example. That makes getting around and being able to take care of yourself easier.

Second, Medicare, Medicaid, and Social Security provide safety nets for millions of elders, despite the confounding paperwork involved. Third, medical technology has made staying healthy more accessible, what with hip replacement, cataract surgery, and better management of heart disease.

How long will you live?

Such statistics are comforting. But statistics are just statistics, overall averages that may or may not apply to you individually. To get a clearer idea of your own destiny, researchers at the San Francisco Veterans Affairs Medical Center recently put together what is called a "mortality quiz." It consists of 12 simple questions, the answers to which show how your weight, health, and coping skills affect your chances of dying in the next four years. No laboratory or performance tests are required, but you must be truthful to yourself when answering the questions.

The questionnaire was originally published in the Feb. 15, 2006 issue of the Journal of the American Medical Association, page 807. It is reproduced below and in the Harvard Health Letter for your convenience.

The health letter points out that an 85-year-old nonsmoking woman without diabetes who has no difficulty walking three to four blocks has the same risk of dying in the next four years as a 60-year-old woman who smokes, has congestive heart failure, and can't walk a few blocks without difficulty.

One surprise is how weight is accounted for. The body mass index (BMI) referred to in one question is calculated by dividing your weight in kilograms (one kilogram equals 2.2 pounds) by your height in meters squared (one meter equals 3.3 feet, squaring means multiplying your height by itself). A healthy index runs between 18.5 and 25. Obesity is 30 or greater. But loss of weight, and thus a lower BMI in old age, might be due to illness. Gaining some weight in old age can actually have a limited protective effect. Extra weight seems to offer some cushion for women from hip fractures and weak, brittle bones, but too many pounds increases the risk for heart disease and cancer.

No short quiz is going to tell the whole mortality story, but the Harvard Health Letter labels this one "about 80 percent accurate." The researchers developed it for relatively healthy people so it doesn't include people who live in nursing homes. Many more whites than blacks are included in the data on which the quiz is based, so blacks and other groups will find it less accurate. Other statistics, for example, give 60-year-old black men and women three years less life expectancy than whites. By age 70, this gap drops to one year.

Why women live longer

One big question remains. Why do women live longer than men? The short answer is that no one really knows. However, one good explanation is the gender gap in heart disease risk. "Women tend to lag behind men in death rates from heart disease," notes JoAnn Manson, Elizabeth F. Brigham Professor of Women's Health at Harvard Medical School. Some of this difference is presumably due to the protective effect of the female hormone estrogen. But some of it may come from traditionally lower smoking rates in middle-aged and older women than in men of comparable ages.

As these smoking differences decrease, Manson speculates, the gender gap in lethal disease rates may also lessen. This would not only include heart disease but also lung cancer, emphysema, and other smoking-related diseases.

"It is interesting to note," she continues, "that before smoking became common, the life expectation of men and women were more similar."

life-expectancy quiz

For more information, see http://www.health.harvard.edu


Copyright 2006 by the President and Fellows of Harvard College