Current
research has drawn a connection between arteriosclerosis being
an inflammatory disease similar to rheumatoid arthritis or lupus.
This correlation has gained momentum over the past 15 years,
maintains that chronic vascular inflammation may have as large
a role in the evolution of MI and ischemic stroke as does hypercholesterolemia.
atherosclerotic vessel wall.
At
present, CRP appears to be the most useful of these in a number
of prospective studies—Have come to show that as levels
of CRP increase so does the risk of heart attack and stroke.
Those patient found to be in the highest quintile for CRP
had 2.6 times the risk of developing heart disease of those
with the lowest levels. Also interesting were the findings
that smokers had twice the CRP levels of nonsmokers, and obese
participants, categorized as those with a body mass index
(BMI) of 30 kg/m2 or more, had double the CRP levels of subjects
with a BMI of less than 25 kg/m2.
A study that examined CRP levels in women also determined
that CRP was a predictor of cardiovascular disease (CVD) In
fact, researchers learned that CRP levels predicted CVD events
even in women whose LDL levels were at the desirable level
of less than 130 mg/dL. A subgroup analysis in this group
revealed that the quartile with the highest concentrations
of CRP had 4 times the risk of those in the lowest segment.
After adjusting for other cardiac risk factors, these participants
still had a relative risk of 3.1, a significant difference.
Figure 4: Shows the risk factors
associated with CRP, extracted from publications authored
by Dr. Paul Ridker. It is important to note that risk factors
vary according to individual publications and may change with
future publications*
*Relative
risk is the ratio of the chance of a disease developing among
members of a population exposed to a factor compared to a
similar population not exposed to the factor
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Figure
4: Risk Factors Associated With C-Reactive Protein (CRP)
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|
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MEN
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RELATIVE
RISK FOR:
|
|
CRP (mg/L)
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Future
MI (Heart Attack)
|
Future
Stroke
|
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>2.11
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2.9
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1.9
|
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1.15
- 2.10
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2.6
|
1.9
|
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0.56
- 1.14
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1.7
|
1.7
|
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<0.55
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1.0
|
1.0
|
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WOMEN
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RELATIVE
RISK FOR:
|
|
CRP (mg/L)
|
Future
MI (Heart Attack)
|
Future
Stroke
|
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>7.3
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5.5
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5.5
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3.8
- 7.3
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3.5
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3.5
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1.5
- 3.7
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2.7
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2.7
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<1.5
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1.0
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1.0
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Ref:
Ridker, et. al. Circulation 1998;98:731-733
Ridker, et. al. N. Engl J. Med., 1997; 336:973-979
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What this suggests is that cholesterol levels indicate how much
atherosclerosis is building up in the arteries, but that CRP
measures the propensity of those plaques to rupture, a process
driven by inflammation. If so, screening could help physicians
detect patients vulnerable to cardiovascular events despite
a seemingly healthy cholesterol profile. For example, it might
be used as an extra check in patients with no evident risk factors
other than a family history of early heart disease. Proponents
note that when added to the cholesterol evaluation in patients
with elevated lipid levels, CRP levels can uncover those in
need of more aggressive treatment.
An
essential point is that the CRP test described here is not
the same assay used to assess inflammation due to other causes,
such as rheumatic disease, acute infection, or MI. Rather,
it is a high-sensitivity CRP or hs-CRP, designed to pinpoint
levels between 0 and 1 mg/dL, since amounts considered normal
(less than 0.8 mg/dL) under other circumstances could actually
be a harbinger of cardiovascular events.
The
approaches traditionally used to lower cardiovascular risk
also reduce CRP levels, providing one more reason why patients
should stop smoking and lose weight. In addition, consider
prescribing low-dose aspirin or treating high cholesterol
levels more aggressively by prescribing one of the statins.
This is one of the few times in our center we consider using
statin drug as the first line of therapy. Studies indicate
that both aspirin and the statin drugs reduce CRP levels and
may even work better in patients with such elevations. Researchers
also plan to explore whether statins can reduce the risk of
MI in patients with high CRP but "low" cholesterol
levels. Other methods used in our center to reduce elevated
CRP include the use of high dose fish oil, Vitamin E, and
the use of a systemic enzyme called Wobnzyme.
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