By Sahar Bedrood B.S. and Asher Kimchi M.D.

Colchester, VT- 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