* Biomarker shows risk but itself does not cause disease
* "Fruitless" to develop drugs to lower protein levels
By Andrew Stern
CHICAGO, June 30 Measuring a compound called
C-reactive protein helps identify people with heart disease,
but a study on Tuesday concluded there is no reason to think
that elevated levels of the substance itself cause heart
A pair of studies published in the Journal of the American
Medical Association revealed limitations in the much-debated
tests for biomarkers such as C-reactive protein, which is
secreted by the liver and signals tissue inflammation and a
risk for heart attack or stroke.
An international study involving 30,000 patients by
researchers from Imperial College London and a dozen other
universities and institutes in Europe and North America
concluded that higher-than-normal levels of C-reactive protein
were likely caused by tissue inflammation, and not a cause of
the inflammation and resulting cardiovascular problems.
"This study puts the nail in the coffin ... in the question
about (C-reactive protein): does it cause cardiovascular
disease?" said Dr. James Lemos of the University of Texas
Southwestern Medical Center, who helped write a commentary in
the journal about the studies.
It clearly does not, he said.
Dr. Paul Elliott of Imperial College, who led the study,
wrote that it would be "fruitless" to develop drugs aimed at
lowering C-reactive protein to prevent heart disease.
Many heart attacks are caused by atherosclerosis, a
narrowing of arteries that can be caused by a build-up of fatty
deposits and inflammation.
UNEXPLAINED HEART ATTACK
For many years doctors have searched for tools to identify
people at risk for sudden heart attack, but "you frequently
encounter the unexplained heart attack," Lemos said in a
Traditionally, the risk factors used to identify risk are
high blood pressure, diabetes, smoking and high cholesterol
levels. Some doctors test their patients for biomarkers, but
the usefulness of the results is debatable, Lemos said.
In the other study by researchers at Massachusetts General
Hospital and Lund University in Malmo, Sweden, 5,000 Swedes
were tested for six potential biomarkers for heart disease and
then monitored for up to 15 years.
While five of the six biomarkers -- including C-reactive
protein -- were useful in predicting future cardiovascular
problems such as heart attacks, they were not helpful in
classifying patients' risk or determining changes in the course
Last year, the JUPITER study found patients who had
higher-than-normal C-reactive protein levels but modest
cholesterol levels had dramatically lower heart risks after
taking the cholesterol-lowering statin drug Crestor,
manufactured by AstraZeneca Plc (AZN.L). That raised the
question whether lowering C-reactive protein could curb heart
Statins that include Crestor and Pfizer Inc's (PFE.N)
Lipitor are the top-selling prescription drugs in the world.
"That is the goal of these tests -- to pick up these
individuals (at risk for heart attack)," Lemos said. He said
while the Swedish study was negative, others had mixed
"Both as a clinician and as an investigator, I still think
at some point we will figure out how to use multiple biomarkers
to predict risk. I don't think this is a failed idea," he said.
(Editing by Maggie Fox and Xavier Briand)