To Test or Not to Test for CRP: Two Experts Provide Different Opinions
Although high sensitive CRP has been available about 15 years, cardiologists are still divided on whether or not testing for this marker of inflammation is needed or helpful for patients. Two cardiology and atherosclerosis experts who had diverse opinions spoke with CSWN about the decision to test patients for high levels of CRP.
CRP Testing Is Still a Complicated, Unclear Issue
By Ira Tabas, MD, PhD
The topic of whether or not to test for CRP is indeed a Pandora’s box among the cardiology community, with parties having adamant opinions one way or the other. At this point, my opinion is that there is not a lot of incremental benefit in terms of changing action that you get by measuring CRP. However, others will claim that it is one of the most important things you can measure.
People claim that physicians can use the measurement of CRP to help make a decision about a patient’s treatment if you are on the fence about their level of risk. For example, if a physician has a patient who is high risk, it is unlikely that you need to test for CRP to make the decision to treat because you would treat this type of patient aggressively anyway. On the other hand, if you have a patient who is low risk, physicians might say that you should measure CRP, and, if it is high, that the patient should be treated.
Currently, I do not think that we have sufficient data to support that opinion. Speaking generally, data could easily support that a large number of people who are not currently on statins would benefit from statins if you consider the big picture and long-term, life-long risk. There is no doubt that inflammation is an important and driving force behind atherosclerosis. However, for the time being, I am still awaiting additional data to support testing a majority of patients for markers of inflammation.
CRP Testing is a Useful Tool for Primary Prevention of Disease
By Paul M. Ridker, M.D., M.P.H., F.A.C.C.
This question is controversial, and you might get a different opinion from me as well, depending on the day that you talk to me about it. Overall, I consider myself a conservative physician in that I would argue that we should not do tests or measure things in medicine simply because they predict risk.
We should measure something if it predicts risk and if there is hard clinical trial evidence that we could provide the patient with an intervention that he or she would otherwise not receive except for the fact that I measured for that biomarker.
That was the logic behind the JUPITER trial, which showed that by measuring people for CRP who would not otherwise be treated who are in situations where CRP is high, I can lower the rate of heart attack and stroke by 50% and lower mortality by 20%.
Our guidelines call for universal screening of total cholesterol. I would argue that clearly what we know is true is that measuring CRP adds as much to risk prediction as does measuring either total cholesterol or HDL cholesterol. The reason I measure total cholesterol is because I know if it is high then I can give a patient a statin and they will do better. Now I know if CRP is high and I give a statin then the patient will do better.
Not every patient needs to have CRP measured because, in secondary prevention, the patient should already be treated with a statin. This is really about primary prevention screening.
Keywords: Atherosclerosis, C-Reactive Protein, Biological Markers
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