Hopkins PodBlog

Is C-reactive Protein a Villain or an Innocent Bystander?

C-reactive protein or CRP is a blood marker of inflammation. First identified in the 1930s, CRP has been intensively studied in the hopes of imbuing it with some predictive power: the higher the CRP level, the higher the risk of cardiovascular disease would be one way of crystalizing a looked for relationship, with clear cause and effect the ideal. Sadly, such a relationship has had a bit of an on-again, off-again character, and in this week's JAMA, two studies further erode CRP's clinical utility.

'Novel and Conventional Biomarkers for Prediction of Incident Cardiovascular Events in the Community' is one of the studies. It assessed CRP levels and other so-called 'novel' blood markers as well as conventional measurements in thousands of people, then asked the question: does the addition of CRP and other biomarkers markedly improve our ability to predict who will develop cardiovascular disease? The answer was largely no.

A second study ('Genetic Loci Associated With C-Reactive Protein Levels and Risk of Coronary Heart Disease') looked at genetic variations associated with CRP levels and found that no cause and effect relationship exists. In other words, CRP is not the smoking gun when it comes to cardiovascular disease. It may be lurking about in the shadows, but it isn't the trigger man.

As Rick says, we are really quite good at using conventional risk factors for predicting who will develop cardiovascular disease for the vast majority of people. Overweight and obesity, diabetes, high blood pressure, sedentary lifestyle, smoking, high cholesterol, and a family history of heart disease are all pieces of the puzzle. The addition of CRP measurement to this doesn't help in the majority of people, although it may help a little bit in those at intermediate risk.

Other topics this week include the risks of walking aids for the elderly to be published in the Journal of the American Geriatrics Society, but here's a news story:http://health.yahoo.com/news/ap/us_med_elderly_falls.html , another swine flu update from NEJM , and failure to prevent kidney complications of diabetes using medications to treat the condition: Renal and Retinal Effects of Enalapril and Losartan in Type 1 Diabetes. Until next week, y'all live well.