After months of speculation about the diagnostic value of a new blood test
to help identify those at risk of heart attack, a national panel led by a
Medical Center researcher recommends limited use of the test. By Laurie Tarkan
A panel of experts has recommended that tens of thousands of people be tested
for a new indicator of heart disease. The indicator, C-reactive protein, is
produced in the liver in response to injury or inflammation, and it can help
identify people at higher risk for heart attack and stroke, including those
with normal cholesterol.
But the panel, convened by the Centers for Disease Control and Prevention
and the American Heart Association, stopped short of recommending the test
for every adult and said that the test should not replace assessments of other
risk factors, like cholesterol, high blood pressure, and diabetes.
People with a low risk of heart disease and those with a high risk will most
likely not benefit from the test, called high sensitivity C-reactive protein,
or hs-CRP, the panel says.
Thomas Pearson, senior associate dean for research at the Medical Center and
professor of community and preventive medicine, who cochaired the panel, helps
clarify the recommendations.
Why did an expert panel write guidelines for testing for a new indicator
of heart disease, known as hs-CRP?
Our response to that question is, How could you not write guidelines? There’s
been tremendous interest generated in the media about the ability of hs-CRP
to predict heart disease, and as a consequence there are a lot of patients
asking doctors to get it. We think hundreds of thousands of hs-CRPs were measured
last year. Clearly a lot of tests are being ordered in people for whom it
won’t make a difference, and likely there are people in whom it would
make a difference who aren’t getting it.
Will you explain the role of CRP, or C-reactive protein, in the hardening
of the arteries that can lead to heart attacks and stroke?
Atherosclerosis is thought to be due to an inflammatory response to arterial
injury. The injury is caused by high blood pressure, cholesterol, smoking,
and other risk factors. Inflammatory cells, along with cholesterol and fatty
substances, form lesions, and these lesions get little rubbery scars that
are prone to rupture. If one ruptures, a core of plaque that has the consistency
of pudding sets up a clot in the artery, leading to a heart attack or stroke.
“If you look at the tests for markers available today, hs-CRP is the best we have, but it may not always be so.”
So where does C-reactive protein come into play regarding inflammation?
One response to the inflammation in the artery is the release of cytokines,
which in turn trigger the liver to raise C-reactive protein levels in the
Is C-reactive protein a unique marker for heart disease?
We’ve known for many years that a number of inflammatory markers predict
coronary events. So this whole idea of markers of inflammation is not exceptionally
new. But if you look at the tests for markers available today, hs-CRP is the
best we have, but it may not always be so.
How is C-reactive protein different from other risk factors like cholesterol?
In our report, we made great care to differentiate between a risk factor and
a risk marker. A risk factor, like high cholesterol, is associated with disease
because it’s a cause of the disease. If you lower that factor, you will
lower the risk of disease. A risk marker, hs-CRP, is predictive of the disease,
but there’s no evidence to suggest it’s a cause. Lowering hs-CRP
doesn’t necessarily mean you’ll lower your risk. It may come to
pass that it’s also a risk factor, but there’s not enough scientific
evidence to support that.
The hs-CRP is a fairly inexpensive test, so why not test every adult?
Labs are charging between $20 and $120, but that’s not the issue. That’s
chump change compared to the cost and burden of the follow-up testing you
According to your panel, who should be tested for hs-CRP?
Typically it’s people who are borderline high risk. First, a doctor
would measure a patient’s major risk factors, like cholesterol, high
blood pressure, smoking, diabetes, sex, and age. Then he’d calculate
the patient’s 10-year risk of developing a heart attack or dying of
heart disease. We have simple formulas we use for that. If the risk falls
between 10 percent and 20 percent, you’re in a situation in which you
don’t know whether to treat this person or not, so doing this test would
help inform your decision.
Preventive Cardiology for
Thomas Pearson, senior associate dean for clinical research at the
Medical Center, also chaired a national panel that is urging
Americans of all ages, even children, to make lifestyle changes—quitting
smoking, eating right, exercising regularly—that are proven to
prevent heart disease before it starts.
The strategy for implementing the changes for the first time at the
community level was outlined in a paper published in Circulation:
Journal of the American Heart Association last winter.
The new guidelines are intended as a roadmap for schools, employers,
civic leaders, policymakers, and others interested in combating heart
disease and stroke, the No. 1 killers in the United States.
Here is a sampling of the recommendations:
• All schools and work sites should provide age-appropriate curricula,
materials, and services to educate people on causes and early warning
signs, and motivate and assist people to improve their lifestyles.
• School gym class should be required at least three times a
week for K-12, with an emphasis on lifetime sports and activities.
• Schools should offer heart-healthy breakfasts and lunches;
TV food advertising directed to youths should be limited to foods that
meet health guidelines.
• All citizens should be assured access to screening, counseling,
and referral services for cardiovascular disease.
• Communities should support farmers’ markets, gardens,
convenient bike routes, safe, attractive, and affordable fitness facilities,
and a smoke-free environment.
• Grocery stores and restaurants should increase their offerings
of foods that meet nutritional guidelines, and promote or display selections
low in saturated fat, sodium, and calories.
Previously, the association’s guidelines have focused on treatment
strategies aimed at physicians and their patients who already have heart
disease, or who have risk factors. But the new recommendations emphasize
the social and environmental origins of heart disease, and attempt to
reach people of all cultures and socioeconomic groups, and overcome
language barriers and literacy gaps.
“Health care providers, teachers, community leaders, and employers
all need to work together to ensure that the places where we live and
work and play promote heart health,” says Pearson, who was the
lead author of the recommendations. “We also need to continue
to be politically active. Cardiovascular disease is our biggest health
threat. Americans need to know about the problem, understand how to
prevent it, and have access to appropriate health care.
“Everyone should be a preventive cardiologist.”
Can people figure out their own 10-year risk?
They can go to the American Heart Association’s Web site, americanheart.com,
which has a risk assessment tool.
Can you give a sense of someone who has a 10 percent to 20 percent chance
of developing a heart attack or dying of heart disease in the next 10 years?
Smoking gets you there very fast; or having two or three elevated risk factors,
like high bad cholesterol, high blood pressure, and being an older male, which
is a substantial number of Americans. If you’re obese, you probably
have several risk factors, and that will get you into that category.
Why do you suggest not testing people for the heart disease indictor if their
risk of having a heart attack in the next 10 years is less than 10 percent?
Or those whose risk is greater than 20 percent?
We feel very strongly you shouldn’t test someone in whom you wouldn’t
do anything different on the basis of the test. You wouldn’t do it in
someone who has coronary disease, a previous heart attack or stroke or diabetes,
as we’re going to treat these people aggressively no matter what the
results of hs-CRP are. Similarly if you have a young person with few risk
factors, you wouldn’t test him either, because you’re not going
to do anything about it. If a young person had a 2 percent risk factor, and
had a high hs-CRP, it would only bring his risk up to 4 percent, which is
a level we still wouldn’t treat.
What is considered a high marker for heart disease based on hs-CRP?
Hs-CRP can be classified as low, average, and high risk. You do two tests,
two weeks apart, and average the two numbers. A low score is less than one
milligram per liter, average is one to three milligrams per liter, and greater
than three milligrams per liter is considered high risk. It turns out that
someone in the high risk group has twice the risk as those in the low risk
group. People with average risk have 1.6 times the risk of those in the low
How do you treat a patient with high hs-CRP?
This is the problem. You don’t treat risk markers. You’re not
treating hs-CRP. You go back and look at other risk factors, and when you
see something on the high side, you treat that symptom. You look at the cholesterol
level. If that’s high, we have a host of powerful drugs we can use.
If the blood pressure is high, we treat that aggressively. If someone didn’t
have any obvious risk factors, we might recommend weight reduction and exercise
programs, or suggest taking 75 to 160 milligrams of aspirin.
If hs-CRP goes down, does that mean you’re reducing the injuries to
the arteries, the inflammation and therefore the risk of heart attack?
One would hope so, but nobody knows what it means. No clinical study has tested
the hypothesis that direct therapy of hs-CRP causes you a good outcome. If the test, though, causes you to take steps to lower cholesterol or lower
blood pressure or reduce your weight, that would lower your overall risk of
Copyright 2003 by The New York Times Co. Reprinted with permission.