New debate on C-reactive protein (CRP) test and statins
Study suggests CRP blood test may not predict heart benefits of statin treatment
28th January 2011 -- Cholesterol-targeting statins protect against heart attacks and strokes even when patients have normal LDL “bad” cholesterol and little evidence of systemic inflammation, new research suggests.
Inflammation is a well-recognised risk factor for these cardiovascular events, but the study found that its presence or absence measured by a CRP blood test did not predict how well patients will respond to statins.
The study is published online first in The Lancet.
Researchers tested the hypothesis that patients with elevated blood levels of the inflammation-marker C-reactive protein (CRP) derive the most benefit from taking statins and that the drugs may not benefit patients with both normal cholesterol and low CRP.
They did this by analysing data from more than 20,000 participants in a UK study - one of the largest statin studies ever conducted. The Heart Protection Study included patients at high risk for heart attack and stroke recruited from 69 hospitals between 1994 and 2001. The patients were treated with a statin or placebo for an average of five years.
Those who took the statin simvastatin had a 24% reduction in cardiovascular events, including heart attacks, strokes and death from cardiovascular causes.
The analysis revealed that patients with the lowest CRP levels had similar reductions in risk as patients with the highest levels of the inflammation marker.
In fact, the risk reduction was about the same for any combination of low or high CRP with low or high LDL cholesterol, the researchers reported.
Assessing heart risk
The findings do not mean CRP is of no benefit as a marker for cardiovascular risk, study researcher Dr Jonathan Emberson tells us.
However, he says it is clear that assessing a patient’s overall risk profile is more important than any single test result when deciding if statin therapy is warranted.
“CRP may be useful to help a physician understand a patient’s absolute risk along with other characteristics like age, sex, blood pressure, and blood lipids,” he says. “But this analysis tells us that a normal CRP doesn’t necessarily mean a statin won’t be beneficial.”
In an editorial, Dr Jean Pierre Despres, of the Quebec Heart and Lung Institute, writes that the new analysis of the Heart Protection Study data “brings more fuel to the healthy debate” about the usefulness of CRP as a predictor of heart attack and stroke risk.
Despres agrees that elevated CRP is clearly predictive of cardiovascular risk, but he says the marker of systemic inflammation is usually seen in people with another cardiovascular risk factor -- obesity.
His own research and that of others suggests a particularly strong association between elevated CRP and belly fat.
He tells us that you are unlikely to see high CRP in a “ vegetarian monk” training for a marathon. He says that by far the greatest driver of elevated CRP “is a sedentary lifestyle and carrying too much fat around the middle.”
Because of this, he says, lifestyle modification has to be part of the discussion about how to lower cardiovascular risk.
“Statins are clearly effective, but lifestyle modification is optimal,” he says.