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Eight Tests That Could Save Your Life; Only a precious few disease-screening tests make a difference in healthy adults. Here's what you need to know.
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On The Cover/Top Stories
1963 Words
08 June 2009
Forbes
52
Volume 183 Issue 12
English
(c) 2009 Forbes Inc.
Only a precious few disease-screening tests make a difference in healthy adults. Here's what you need to know.
No modern doctor would have been surprised at Franklin Delano Roosevelt's death from a cerebral hemorrhage in 1945. His blood pressure was 260 over 150 millimeters of mercury, double the normal level.
Blood pressure, measured by how far pulses of blood in your arm push up a column of mercury, is one health-related number everyone should worry about. But it's on a very short list. If you're healthy and trying to stay that way, the important tests are few and relatively low tech. Measure your cholesterol. Step on a scale. Check for signs of a small number of cancers and tell your doctor if you feel depressed.
This advice may run contrary to what might be characterized as test madness--the tendency of doctors and patients to want to test in all sorts of ways, using dozens of parameters that purport to measure how well your internal bodily engine is running. More are proposed and touted by entrepreneurs all the time--such as exotic new genetic tests and whole-body scans. They claim they will spot disease before symptoms arise. But most have no data proving that taking the test will improve your health or lengthen your life.
"There are five things that can happen with a screening test, and four of them are bad," says B. Ned Calonge, the Colorado doctor who is chairman of the U.S. Preventive Services Task Force, a government-sponsored expert panel that evaluates preventive tests. Tests can indicate you have a disease you don't. They can tell you don't have a disease you do, leading you to ignore symptoms. They can spot a slow-growing disease you might be better off not knowing about. And they can waste money with unhelpful information.
Conclusion: Before you take an exotic test, talk to your doctor about whether taking it will really improve your health.
The Preventive Services group takes a conservative approach and tries to cherry-pick the few tests that are highly likely to lead to better health. Its list of recommended screening tests for healthy adults provides the basis for ours; we've added an overall calculator for heart risk, and waist circumference, which many cardiologists believe may spot risky amounts of abdominal fat.
Most of our tests screen for the risk of heart disease and stroke. Cardiovascular disease slays 800,000 Americans a year, 60% more than cancer, the runner-up killer. Heart disease put the whole idea of risk screening on the map. The Framingham Heart Study, which has followed 5,000 patients in Framingham, Mass. for half a century, established blood pressure and cholesterol as risk factors way back in 1961.
Routine blood panels done by doctors often include dozens of obscure numbers. Finding out many of these lab numbers might not hurt, but there's not a lot of proof they'll help you in the long run. If you do enough tests, one will be high just by chance-- causing unnecessary anxiety and yet more tests.
Health is not just about the numbers. Too often, "the abnormality on the screening test has become the disease," says Peter Bach, a pulmonologist and epidemiologist at Memorial Sloan-Kettering Cancer Center. Equating the number with the disease can lead to problems. In one big study diabetics who had their blood sugar lowered all the way back to normal died sooner than those who had it lowered somewhat less. So stick to treatments that have been proved in clinical trials.
Blood Pressure
Optimal: 120/80 mm Hg or lower Borderline: 120/80 to 140/90 mm Hg High: above 140/90 mm Hg
Every 20-point increase in blood pressure doubles your risk of dying from a heart attack or stroke. The top number measures the pressure of blood flowing through your arm when your heart beats; the bottom is the pressure between beats. Even people over age 80 cut their risk of death by 20% if they lower their blood pressure by 15 points with drugs, a 2008 New England Journal of Medicine study found. Various categories of blood pressure drugs lower heart risk; many are cheap generics. Lifestyle changes--such as losing weight, cutting salt intake or increasing fruit and vegetable intake--can have an effect similar to taking a single blood pressure medicine.
Bad Cholesterol (Low-density lipoprotein, or LDL)
Optimal: LDL less than 100 milligrams per deciliter of blood Normal: LDL between 100 and 129 mg/dL Borderline: LDL 130 to 59 mg/dL High: LDL 160 to 190 mg/dL Very high: over 190 mg/dL
Ideally, a person's low-density lipoprotein should be under 100, as it was in your average hunter-gatherer. But national guidelines generally don't push drug treatment until levels reach 160. In people with heart disease, it appears, any lowering of LDL is accompanied by a survival benefit. But extrapolating those results into healthy people requires a leap of faith. The Preventive Services Task Force recommends screening starting at age 35 for men (who are at risk for heart disease earlier) and at 45 for women. The National Cholesterol Education Program recommends screening all adults over 20.
Overall Heart Risk
Low: less than 10% chance of developing or dying from heart disease in ten years Medium: 10% to 20% chance High: more than a 20% chance
A careful internist calculates your risk level before prescribing cholesterol-lowering statin drugs. That risk depends not merely on LDL but on factors like your age, gender, blood pressure and whether you smoke. If your doc shortchanged you, do the work yourself. One risk calculator, based on heart disease rates among residents of Framingham, Mass., can be found by Googling Framingham Risk Calculator; the site is run by the National Institutes of Health. A newer calculator is the Reynolds Risk Score (http://www.reynoldsriskscore.org). It adds family history and results from a blood test for high sensitivity C-reactive protein (CRP), a measure of inflammation (high CRP is above 3 milligrams per liter). You can ask for CRP to be included in your next blood test; it might add $50 to the lab's bill. And once you know your risk level, talk to your doctor about whether you need a statin, blood pressure drugs or lifestyle changes.
Body Mass Index
Obese: 30 kilograms or more of weight per meter squared of height Overweight: 25 to 30 kg/m2Normal weight: 18.5 to 25 kg/m2
Obese people have a higher mortality rate, especially from cardiovascular disease. They are more likely to get diabetes, arthritis and certain cancers. Obesity is defined as a body mass index (BMI) above 30. BMI, in turn, is an abstract ratio that compares a person's weight to the square of his height. As a shortcut, multiply your weight in pounds by 703 and divide the result by the square of your height in inches; or go to
http://www.nhlbisupport.com/BMI. Being very underweight raises the risk of death, too. Whether being moderately overweight will kill you is murkier, with studies showing conflicting results. One reason: BMI is a crude metric that doesn't directly measure the level of abdominal fat. (It overstates the obesity of muscle-bound athletes and understates that of flabby people.) Abdominal fat is probably a driver of heart risk.
Waist Circumference
Men: risky if at or above 40 inches Women: risky if at or above 35 inches
Another metric that may help distinguish people at high risk of cardiovascular disease is the waist circumference. People with bulky waistlines are significantly more likely to die over the next ten years, even if they aren't obese or overweight, according to a 2008 study of 359,000 European men and women published in the New England Journal of Medicine.
Osteoporosis
Bone mineral density (T-score)Normal: 0 to --1 Low bone density: --1 to --2.5 Osteoporosis: --2.5 or lower
The Preventive Services panel recommends bone density screening for women starting at age 65, when osteoporosis becomes more common, or at age 60 if other risk factors are present, such as previous fractures. It doesn't yet make a recommendation for men, who have much lower fracture rates. (The American College of Physicians recommends older men get screened if they have risk factors such as previous oral steroid treatment.) The most common test, a T-score, measures how much less dense your bones are compared with those of an ethnicity-matched 30-year-old. The most relevant tests measure the bone density in the hip or spine, where fractures are most serious.
It can make sense to take other risk factors into account. To estimate your hip fracture risk based on World Health Organization data, Google "frax" or go to
http://www.shef.ac.uk/frax, click on the phrase "Calculation Tool" in the drop-down menu and select your country and race. You can leave question 12 (on bone mineral density) blank. A 3% ten-year risk of hip fracture made drug treatment cost-effective, a 2008 study found.
Blood Sugar1
Normal: under 100 mg/dL Prediabetes: 100 to 125 mg/dL Diabetes: 126 or higher mg/dL 1There are multiple tests; these numbers are for the fasting plasma glucose test.
Diabetes kills mostly through heart disease. If you don't have symptoms, you can wait to get your blood sugar tested until your blood pressure is high or you are considering treatment for high cholesterol, Preventive Services says. Diabetics need more aggressive blood pressure and cholesterol lowering, in addition to treatments to lower their blood sugar. Preventive Services says there is "insufficient evidence" to recommend blood sugar tests for all older adults, as no trial proves that doing this saves lives. The American Diabetes Association recommends blood sugar tests for all individuals over 45. For those in the high-risk prediabetic category, diet and exercise are more effective than drugs at preventing full-blown diabetes (so found a big 2002 government trial). GOP presidential candidate Mike Huckabee reversed his diabetes by dieting.
Cancer Screening
Numerous cancer screenings have been proposed over the years, but Preventive Services recommends only three: Pap smears for cervical cancer; colonoscopy or other screening tests for colon cancer in men and women starting at age 50; and mammograms in women starting at 40. Pap smears are credited for dramatically reducing cervical cancer deaths, and some trials have shown that mammograms prevent breast cancer deaths.
The group recommends avoiding many other cancer screens, including blood-in-urine tests for bladder cancer (too many false positives); various tests to spot ovarian cancer (many false positives); testicular cancer exams (unlikely to provide benefit); ultrasound to spot pancreatic cancer (no evidence this helps); and prostate-specific antigen tests for men 75 and up (who are likely to die from something else). Recent studies in younger men showed that tests for psa lead to lots of treatment but save few lives, as prostate cancer is such a slow killer. Skepticism may be warranted.
Additional Tests
Preventive Services also recommends: HIV tests for adults at increased risk; chlamydia and gonorrhea tests for sexually active young women; one ultrasound check for aortic aneurysms in male smokers and former smokers between ages 65 and 75; counseling to consider BRCA1 and BRCA2 breast cancer gene tests in women at risk due to family history. Talk with your doctor about your alcohol use and if you are frequently sad. Pregnant women need additional tests.
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(c) 2009
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