Simplicity still rules for heart disease forecast

Content provided by the Faculty of the Harvard Medical School

Simplicity still rules for heart disease forecast

New heart disease tests add little to the predictive power of blood pressure, cholesterol, and other traditional risk factors.

One of the $64,000 questions in cardiology today is, "What is the best way to predict who is likely to have a heart attack and who isn't?"

Over the years, scores of tests and tools have been trotted out to estimate the likelihood of having a heart attack. They range from inexpensive blood tests to costly heart scans. Work on these tests has cost millions of dollars, led to thousands of published studies, generated considerable controversy among doctors, and sowed confusion among the rest of us.

So far, none of these tests or cool tools trumps the mundane octet of age, sex, race, total cholesterol, HDL (good) cholesterol, blood pressure, smoking status, and presence of diabetes. And according to a new study, the newbies add little or nothing to the estimation of heart attack risk.

Prediction match-up

The study that gave us the term "risk factor" — the legendary Framingham Heart Study — also gave rise to the first good tool for gauging an individual's risk of developing heart disease. Back in 1998, Framingham researchers published a seven-step score sheet. It assigned points to various ages, cholesterol and blood pressure levels, and smoking and diabetes status. You tallied up your points, then consulted an accompanying chart, which equated various point totals with the chances of having a heart attack over the next 10 years.

The score sheet is simple, easy to complete, cheap, and generally accurate. It does, though, tend to underestimate heart disease risk in blacks and overestimate it in Asians and Hispanics. And the estimates get fuzzy for people over age 65. The database and equations have been incorporated into dozens of risk assessment tools (see "Your heart disease risk").

A team involved with the Atherosclerosis Risk in Communities Study, a long-term study designed to look at new markers for heart disease, compared the standard Framingham tool with 19 other tests. They did this by examining how well each of these predicted the development of heart disease among 16,000 initially healthy men and women over a 20-year period.

The standard Framingham risk tool worked pretty darned well. It was about 80% correct in identifying those who went on to develop heart disease, the researchers reported in the July 10, 2006, Archives of Internal Medicine. Adding new tests or risk factors to the mix did little to improve on this. The two best, a marker of inflammation called interleukin-6 and a measure of vitamin B₆ in the bloodstream, improved the estimate by just 1%. C-reactive protein, another trendy new marker, improved the estimate by 0.3%. The results were similar in men and women, whites and blacks.

The results support using the simple, fast, and free Framingham tool to gauge heart disease risk. People it identifies as low risk and high risk don't need more tests, while those in the nether zone in between may. One of the beauties of the old standbys included in this tool is that you can modify several of them, like blood pressure, cholesterol, and smoking, and by doing so decrease your risk.

Odd risk factors

Most indicators of heart disease risk — like cholesterol and blood pressure — are scientific and sensible. A few that have been uncovered, though, are oddballs.

Ear lobe creases. People with a diagonal crease or dent on one or both earlobes have a higher-than-average chance of developing heart disease.

Baldness. Heart disease is somewhat more common in men who begin losing their hair early.

Gray hair. Premature graying has been linked with heart disease.

Leg length. The longer your legs, the lower your risk of heart disease.

Short stature. Adults who are on the short side are more likely to develop heart disease and tend to have a higher risk of atrial fibrillation.

Future risk

Why bother with the somewhat morbid task of calculating your heart disease risk? Learning that you have a one-in-five chance of having a heart attack in the next few years can be a powerful motivator to stop smoking, lose weight, start exercising, or take up other healthful habits. Finding out that your risk is low can ease your mind and reinforce the good things you are doing for your heart and the rest of you. In addition, doctors use these estimates to decide who needs medications and how aggressively to go after their risk factors.

The search for better ways to gauge heart disease risk hasn't been fruitless. The basic science underpinning the pursuit of new tests and tools is helping explain how heart disease occurs and may lead to new ways to treat it. And it's entirely possible that a single new test may someday surpass the old standby. Until then, the old tool rules.

Your heart disease risk

Heart disease risk calculators abound on the Internet. Two good ones are a Framingham risk calculator from the National Heart, Lung, and Blood Institute (health.harvard.edu/104) and Your Disease Risk (health.harvard.edu/105) from the Harvard School of Public Health.

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Last updated:	September 05, 2008

Medical content reviewed by the Faculty of the Harvard Medical School. Harvard Health Publications, Copyright © 2007 by President and Fellows of Harvard College. All rights reserved. Used with permission of StayWell.

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