July 8, 2005
Bedrood B.S. and Asher Kimchi M.D.
C-reactive protein (CRP) is a marker for inflammation that has
been reported to be a risk factor for myocardial infarction in
many studies. High CRP is associated with increased coronary
heart disease. In a study conducted by Mary Cushman M.D., MSc et
al from the Departments of Medicine and Pathology at the
University of Vermont, baseline CRP and 10-year incidence of
first MI or CHD death were compared. This observational cohort
study, published in the July 5, 2005 issue of Circulation,
determined that in older men and women, elevated CRP measurement
was associated with an increased 10-year risk of CHD.
The study analyzed baseline CRP and 10-year incidence of first
MI or CHD death in the Cardiovascular Health Study (CHS), a
cohort of men and women greater than 65 years of age. They
categorized CRP as low (< 1 mg/L), intermediate (1 to 3 mg/L) or
elevated (>3 mg/L).
The Baseline CRP was
measured in 3971 men and women > 65 years of age without prior
vascular disease. Among these participants, 29% had CRP <1.0
mg/L, 45% had levels of 1 to 3 mg/L and 26% had elevated values
(>3 mg/L). With 10 years of follow-up, 547 participants
developed coronary heart disease, which was defined as
myocardial infarction or coronary death. With the elevated CRP,
the 10-year cumulative CHD incidences were 33% in men and 17% in
women. The age, ethnicity and sex-adjusted relative risk of CHD
for CRP > 3 mg/L as compared to a low CRP level was 1.82 (95%
CI, 1/46 to 2.28). After adjusting for conventional risk factors
for coronary heart disease, the relative risk reduced to 1.45
(95% CI, 1.14 to 1.86). The population-attributable risk of CHD
for elevated CRP was 11%.
The study also assessed whether CRP improved predictions by the
Framingham Risk Score. They found that among men with a 10-year
Framingham-predicted risk of 10% to 20%, the observed CHD
incidence was 32% for elevated CRP.
CRP appears to be
a useful tool for assessing risk of CHD to men and women greater
than 65 years of age. Elevated CRP levels of > 3 mg/L are
associated with an increased risk of coronary heart disease.
Co-authors: Alice M. Arnold, PhD; Bruce M. Psatsy, MD, PhD; Teri
A. Manolio, MD PhD; Lewis H. Kuller, MD, DrPh; Gregory L. Burke,
MD, MS; Joseph F. Polak, MD, MPH; Russell P. Tracy, PhD