Sensitive Blood Test Marginally Improves Cardiac Diseases Risk Appraisal

The highly sensitive C-reactive protein (CRP) screening test only minimally improved the risk assessment in middle-aged patients with traditional cardiovascular disease risk factors.

Investigators had found that taking a cholesterol-lowering statin reduced first cardiovascular event by 37% in people who primarily had normal cholesterol levels and no other risk factors except elevated CRP.

However, in an analysis of 4,853 patients in the United Kingdom and Ireland, CRP measurements below the median level were not associated with reduced cardiovascular events compared with those with CRP above the median after adjusting for other risk factors and the changes in low-density lipoprotein (LDL). Participants in the analysis were 65 years old on average, predominantly male, with total cholesterol levels under 250 mg/dL of blood, including levels considered normal to moderately elevated. In the treatment group, the statin drug reduced LDL by 40% and reduced median CRP by 27% over six months.

The investigators found those participants' baseline levels of LDL cholesterol, the so-called "bad" cholesterol, and levels of CRP were both predictive of cardiovascular events. However, after the researchers considered other risk factors at the start of the study, or in-trial changes in LDL, the changes in CRP were no longer linked to cardiovascular events. Cardiovascular events occurred in 485 participants during the 5.5 years of follow-up. Those cases were age and sex-matched with 1,367 controls from within the group who had not had a cardiovascular event. The scientists then used statistical models to evaluate the association between cardiovascular events and patients' cholesterol and CRP levels.

Peter S. Sever, FRCP, the principal investigator from Imperial College London, (London, UK), said, "Our key findings are that if you measure CRP at baseline in a population of middle-aged and elderly people with high blood pressure, and with a few additional risk factors for cardiovascular disease, it does independently predict cardiovascular events over the course of our trial. But when you add screening CRP values to a conventional risk model used by doctors, such as the Framingham Risk Score, CRP really has a very small additive effect." The results of the study were presented at the American Heart Association's Scientific Sessions, held in Chicago, IL, USA, during November 13-17, 2010.

Related Links:
Imperial College London
American Heart Association