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CRP vs. LDL for Predicting Cardiovascular Risk

CRP and LDL may identify different groups of people who are at risk for a first adverse cardiovascular event.

Levels of C-reactive protein (CRP), an inflammatory marker, and of LDL cholesterol each predict adverse cardiovascular events. To compare CRP with LDL directly, investigators measured baseline levels of both in 27,939 healthy Women's Health Study participants. Incidence of MI, ischemic stroke, coronary revascularization, and cardiovascular death were assessed prospectively during a mean 8-year follow-up.

Participants were stratified into quintiles of both CRP and LDL levels. Progressively higher levels of each showed clear, inverse linear correlations with event-free survival rates over time, even after adjustment for age, smoking status, diabetes, blood pressure, and hormone replacement therapy. Notably, CRP predicted event-free survival and each event type even better than LDL did. CRP and LDL levels were correlated only minimally.

Median CRP level was 1.52 mg/L; median LDL level was 123.7 mg/dL (3.20 mmol/L). When women with below-median CRP and below-median LDL levels were used as the reference group, multivariable-adjusted relative risks for a first event were these: below-median CRP, above-median LDL (1.5); above-median CRP, below-median LDL (1.5); above-median CRP, above-median LDL (2.1). When the analysis was confined to nonusers of HRT, the RRs were 1.5, 1.7, and 2.4, respectively.

Comment: The authors conclude that CRP may be better than LDL for predicting adverse cardiovascular events and that CRP adds predictive value. The precise role CRP plays in cardiovascular disease remains unclear: Is it really a risk factor? An accompanying editorial cautions against widespread CRP screening before it is clear exactly how clinicians should use screening results. Also note that statin therapy has been shown to be as effective in reducing adverse event rates in people with elevated CRP as in people with elevated cholesterol (Journal Watch Cardiology Aug 31 2001). Future trials must assess whether reducing CRP levels, with statins or by other means, actually limits event rates.

— Joel M. Gore, MD

Published in Journal Watch Cardiology December 13, 2002

Citation(s):

Ridker PM et al. Comparison of C-reactive protein and low-density lipoprotein cholesterol levels in the prediction of first cardiovascular events. N Engl J Med 2002 Nov 14; 347:1557-65.

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Mosca L. C-reactive protein -- To screen or not to screen? N Engl J Med 2002 Nov 14; 347:1615-7.

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• Medline abstract (Free)