An article appearing in the November 14 issue of the New England Journal of Medicine confirms that, at least in women, an elevated blood level of C-reactive protein (CRP) is strongly predictive of future cardiovascular events (such as heart attack and stroke.) These results came from an analysis of over 20,000 blood samples taken from women enrolled in the Women's Health Study, a long-term study which enrolled and followed apparently healthy women for a number of years.
While elevated CRP levels have been known to be associated with cardiovascular risk for several years, this new report offers striking evidence that elevated CRP may be just as important as elevated LDL cholesterol levels; and that furthermore, high CRP levels may identify high-risk patients who would be "missed" by just measuring cholesterol levels. In this study, women with low CRP and low cholesterol did well; while those with high CRP and high cholesterol had very high risk. Women with either high CRP or high cholesterol also had elevated risk - indeed, those with high CRP but normal cholesterol apparently had a higher risk than those with normal CRP and high LDL cholesterol.
In other words, CRP is an independent marker of cardiovascular risk, and may be a partial explanation for why some patients develop significant coronary artery disease despite normal cholesterol levels.
CRP is a protein released into the bloodstream any time there is active inflammation in the body. (Inflammation occurs in response to infection, injury, or various conditions such as arthritis.) Evidence is accumulating that atherosclerosis (coronary artery disease) is an inflammatory process. The fact that elevated CRP levels are associated with an increased risk of heart attack tends to support the proposed relationship between inflammation and atherosclerosis.
Does this new study mean that CRP levels should be measured routinely?Well, perhaps it does, but not everyone agrees.
In an editorial accompanying the November 14 New England Journal article, Dr. Lori Mosca from Columbia University argues that CRP should not be measured routinely, at least not until randomized trials are conducted that confirm this finding, and until effective ways of treating elevated CRPs level are identified.
This is the scientifically correct answer, of course, and to say anything else would have placed Dr. Mosca in professional contempt. However, while scientific "proof" is not yet available, in DrRich's opinion the circumstantial evidence is now strong enough to convict beyond a reasonable doubt. To fully characterize an individual's risk of cardiovascular "events," measuring CRP should be added to the list of screening tests.
How are elevated CRP levels treated?There's the rub. We still don't know the best ways to reduce CRP levels, or even whether reducing CRP levels will, in turn, reduce cardiovascular risk. However, there is suggestive evidence that both aspirin and statin drugs can reduce CRP levels and cardiac risk even in people with normal cholesterol levels. There is a good argument to be made for taking daily aspirin if CRP levels are elevated, and some doctors would even start therapy with statins in these circumstances. (A large randomized trial is being planned to test statins in patients with high CRP and normal cholesterol levels. Unfortunately, it will be several years before the results of this study will be available.)
Certain lifestyle changes can also lead to a reduction in CRP levels. Smoking elevates the CRP levels, so quit smoking. Further, metabolic syndrome x is associated with high CRP levels. This fact provides us with yet another compelling reason to reduce our weight and exercise regularly. And finally, a common cause of elevated CRP levels is periodontal disease (gum disease) - and poor oral hygiene has been associated with a risk of heart attacks and stroke. In fact, dentists are engaged in studies to see whether an antibiotic gel rubbed on the gums can reduce CRP levels and cardiovascular events.