For the last decade, the drumbeat has been building. New tests have come along that supposedly will improve our ability to estimate a person's risk of a heart attack. Right now, you are supposed to know your cholesterol numbers and your blood pressure. Do you also need to know your C-reactive protein (CRP)?
The CRP test is one of the new markers for heart disease risk. CRP is a blood test that reflects inflammation within the body. Researchers have become convinced over the last decade that the body's arteries are not just tubes that carry blood — they are living "systems," and atherosclerosis is the result of the process of damage and repair to the linings of the arteries. This process produces inflammation just as surely as a scrape causes redness on the surface of your skin — and a CRP rise as well.
Why do we need CRP testing when we already have several types of cholesterol to worry about? Low-density lipoprotein (LDL) and high-density lipoprotein (HDL) cholesterol are in fact wonderful tests, but the painful truth is that about half of heart attacks occur in people with normal lipid profiles. Some cardiology experts are increasingly hopeful that CRP will improve our ability to figure out who has the highest risk of heart disease among people whose cholesterol data seem just fine.
Several studies have shown that, among people with normal cholesterol numbers, the people with increased CRP levels have a several-fold higher risk of heart problems. Not only that, at least one study found that treatment of people with normal LDL cholesterol and high CRP levels led to a reduction in their risk of heart attacks. On the other hand, statins (extremely effective cholesterol-lowering drugs) did not do anything for patients with normal LDL and low CRP levels.
Based on information available so far, it sounds like a good strategy would be:
- Get screened for cholesterol levels.
- If your levels are high, get treated.
- If your cholesterol levels are normal, consider a CRP test.
- If your CRP level is low, relax.
- If your CRP level is high, consider a statin, especially if you have other traditional risk factors for heart disease.
If this becomes the standard of care, it will mean that about three-fourths of adult Americans will be taking a statin — so the public health and economic consequences are huge. So huge, that most experts hedge when asked if everyone should get their CRP measured today.
As safe as statins are, they still occasionally have side effects. While CRP testing may help some people decide about the need for a lifetime of statin therapy, we still do not know if a person with an isolated high CRP without any other risk factors should take these drugs.
Thomas H. Lee, M.D., is the chief executive officer for Partners Community HealthCare Inc. He is a professor of medicine at Harvard Medical School. He is an internist and cardiologist at Brigham and Women's Hospital. Dr. Lee is the chairman of the Cardiovascular Measurement Assessment Panel of the National Committee for Quality Assurance.