SAN FRANCISCO - It turns out that answering 12 simple yes or no questions can give you a decent idea of whether you're going to be alive in 10 years, at least if you're older than 50. (SEE QUESTIONS BELOW.)
University of California, San Francisco researchers have created an index that may help predict the chances of older people living an additional decade.
The index is not exactly a crystal ball. But the hope is that doctors can use it to identify which patients may benefit from preventive interventions and which ones might not have enough years left to justify costly and burdensome screenings.
The survey incorporates the idea of "lag time-to-benefit," or the time between when a screening points to the emergence of a disease and when the patient starts having serious problems.
A colonoscopy, for example, might detect a small abnormal polyp that could develop into full-blown colon cancer in eight years, said Dr. Marisa Cruz, the lead author of the study. If that is the case, then it might not be worth the burden, risks and costs of close surveillance if the patient is likely to live five more years in the first place.
"If your life expectancy is less than the lag time-to-benefit, then those preventive interventions are more likely to expose you to harm than to improve your health outcome," Cruz said.
On the other hand, she said, if the index points to a longer life, then it may be worth being more aggressive.
All interventions carry the risk of negative side effects and many are expensive. Some, like colonoscopies, are burdensome. The stress of not knowing test results and of false positives also factor into the overall onus of the tests.
The index was reported this month in the Journal of the American Medical Association. Researchers examined data from between 1998 and 2008 of 20,000 adults nationwide who were at least 50 years old.
Factors on the 12-item survey included age, sex, health history and lifestyle. The higher the score patients received -- out of a total of 26 -- the more likely they were to die within the next 10 years.
Men, you automatically get two points. Older people get more points, and people with chronic lung disease, non-skin cancers and heart failure have points tacked on. Tobacco use and diabetes add points. And trouble bathing, managing your finances, walking several blocks, and pulling or pushing large objects all add up to higher scores.
Women who scored a zero -- healthy, fit and younger than 60 -- had a 3 percent chance of dying in the 10-year period, according to the report. Younger and healthy men with just two points had a 6 percent chance of dying.
Anyone with a score of 14 or higher, however, had a 95 percent chance of dying in the decade.
"Preventive interventions, such as cancer screenings, expose patients to immediate risks with delayed benefits, suggesting that risks outweigh benefits in patients with limited life expectancy," the authors wrote.
Fewer procedures for people who do not really need them also mean lower costs. One person abstaining from an extra colonoscopy might not save substantial money, but thousands of people making that choice every year could lead to considerable reductions.
The survey was an update to a four-year mortality index released in 2006. The researchers found that the risk factors on the earlier index served as valid predictors of 10-year survivability rates.
"Both indices actually identified the same risk factors for intermediate longevity and long-term longevity," Cruz said.
Dr. Yusra Hussain, the director of the Stanford Senior Care Center, said the study affirmed what clinicians have been practicing for years with patients. She also said many patients decline tests on their own.
"They understand their limitations and they might find these interventions cumbersome," she said.
A 2001 study about cancer screenings in elderly patients also from UCSF researchers said, "Patients with life expectancies of less than 5 years are unlikely to derive any survival benefits from cancer screening."
Aggressive diabetes therapies are another example of interventions that might not be worth their potential benefits for people with short life expectancies.
There are those, of course, who want every possible test and intervention, experts said. But most people prefer spending their final years at home and in places they feel connected to rather than in the hospital, said Karyn Skultety, the vice president of home care and support services at the National Institute on Aging.
Skultety said that patients who at first want aggressive interventions may have a change of heart if they are getting the information about risks versus rewards from a doctor they are close to.
"As long as it's someone they trust, most people will make decisions about quality of life rather than quantity of life," Skultety said.
-- Calculating the odds of dying --
University of California, San Francisco researchers have developed a 12-item index to estimate the chances of someone 50 years old or older living an additional 10 years.
Points are allotted based on age, gender, disease, overall fitness and tobacco use. The greater number of points a person is assigned, the more likely that person will die during the next decade. The goal is to determine which patients should consider preventive interventions.
-- 60-64 years: 1 point
-- 65-69 years: 2 points
-- 70-74 years: 3 points
-- 75-79 years: 4 points
-- 80-84 years: 5 points
-- 85 or older: 7 points
Men: 2 points
Current tobacco use: 2 points
Low body mass index: 1 point
Diabetes: 1 point
Non-skin cancers: 2 points
Chronic lung disease: 2 points
Heart failure: 2 points
Difficulty bathing: 2 points
Difficulty managing finances: 2 points
Difficulty walking several blocks: 2 points
Difficulty pushing or pulling large objects: 1 point
Drew Joseph is a San Francisco Chronicle staff writer. E-mail: email@example.com and Twitter: @drewqjoseph.