hsCRP: A new player on the cardiovascular risk stratification stage

Medical Tribune January 2009 P2&3

Dr. Jacques Genest, director of cardiology and Novartis Chair in Medicine at McGill University, Montreal, Canada, addresses the emerging role of high-sensitivity C-reactive protein in predicting cardiovascular risk.

High-sensitivity C-reactive protein (hsCRP) represents a new paradigm in the assessment of cardiovascular risk. It is set to become the first new biomarker for 30 years to be incorporated into routine clinical practice alongside traditional tests such as blood pressure and cholesterol. Guidelines across the world are under review, and it is only a matter of time before hsCRP becomes an integral tool in the risk stratification armory of the primary care physician.

The recent Justification for the Use of Statins in Prevention (JUPITER) trial showed that treating patients who had elevated hsCRP in the absence of other risk factors could significantly reduce the incidence of major cardiovascular events. After a median of 1.9 years of follow-up, the occurrence of cardiovascular death, myocardial infarction, stroke, arterial revascularization or hospitalization for angina was reduced by 44 percent in those treated with rosuvastatin (20mg daily). [N Engl J Med 2008 Nov 20;359(21):2195-207]

These results do not justify testing everyone for hsCRP, but rather suggest that the test will be of great benefit for patients who occupy the grey area between low and high risk. A high hsCRP score can push a debatable case over the treatment threshold while a low score, conversely, can confirm that the patient does not require treatment. Those already deemed to be at high-risk should receive treatment regardless of hsCRP, so the test will add little prognostic value in these patients, while at the other end of the scale there is not sufficient evidence to support routine hsCRP testing in young, healthy people with no other risk factors.

Physicians should begin, therefore, by performing a full and complete cardiovascular risk stratification including sex (until menopause in women), age, physical activity levels, diet, diabetic status, blood pressure and LDL, HDL and total cholesterol levels. For patients who are not obviously at high or very low risk, the physician should now routinely include an hsCRP test. Present evidence suggests that this strategy should be adopted in all men aged over 50 and women aged over 60 – the population that was successfully targeted for treatment in JUPITER. In my opinion, hsCRP will ultimately prove to be of use in men aged over 40 and all postmenopausal women, since these years often herald an increasingly sedentary lifestyle whereby the long-term outcome is likely to be heart disease or cancer. We await the support of local guidelines on this point, however, and at present physicians should exercise their own judgment as to the appropriate age for introducing hsCRP testing.

JUPITER treated patients with hsCRP levels of 2.0 mg/l or higher, and physicians may wish to adopt this level as their cut-point for deciding whether to initiate treatment. There is, however, strong epidemiological data and an ongoing argument in support of adopting a threshold of 3.0 mg/l or higher. This, again, will prove a matter for the guideline makers to decide and is likely to vary from country to country. For those with socialized medicine the cost implications of adopting the lower threshold will be considerable, and will prove an important factor in this decision.

Introducing routine hsCRP testing will undoubtedly increase the number of patients being treated with statins. We must not lose sight, however, of the continued importance of diet and lifestyle interventions, for which there is incontrovertible evidence in favor. Physicians should continue to press the message on five fronts: smoking cessation, quality of diet, quantity of diet, daily exercise, and serenity. The latter encompasses both stress management and levels of social interaction – both important prognostic factors in long-term mortality outcomes. Addressing these issues in a single consultation can be difficult – particularly when seeing the patient only once every 6 to 9 months – and I would recommend that GPs refer certain cases to a dietician and kinesiologist in order to improve motivation through more regular advice and feedback.

Many biomarkers have come and gone over the past 20 years of my research career but very few have proven to be clinically useful. Homocysteine, inflammatory factors, cell adhesion molecules, matrix metalloproteinases, and enzymes such as lipoprotein-associated phospholipase A2 have all failed or are still not ready for primetime use. These markers may predict disease but that does not mean that targeting them will automatically yield a reduction in hard clinical trial endpoints.

The journey towards hsCRP testing has been a long one but the marker has finally matched our ability to predict with our ability to prevent, while also asserting its independence from other risk factors. Guidelines will change in time, but in the face of the evidence from JUPITER physicians may decide not to wait. The time is right, in my opinion, to begin measuring hsCRP and implementing the appropriate strategies in the JUPITER-like patient while we await further international guidance. Unlike other biomarkers, hsCRP testing is here for good.

Dr. Genest is one of the investigators of the JUPITER trial and reports receiving consulting fees from AstraZeneca, Merck, Merck Frosst, Schering-Plough, Pfizer, Novartis, Resverlogix and Sanofi-Aventis.