For years, doctors have used cholesterol as the main measure of a person's heart health, but a new study suggests that testing for another substance in the blood may be just as important.
Aggressively lowering cholesterol as well as a substance in the blood known as C-reactive protein, or CRP, led to a greater reduction in heart attacks, strokes and deaths than cutting cholesterol alone, according to research presented at a cardiology meeting Sunday and published on the Web site of the medical journal The Lancet.
The study is the latest evidence suggesting that CRP testing should be done in large numbers of middle-aged people who normally would not be considered at risk for cardiovascular disease because their cholesterol levels are acceptable. It follows landmark research in November showing heart attacks and strokes were reduced in people with healthy cholesterol levels who substantially reduced levels of CRP in their blood by taking the cholesterol drug Crestor, one of the most potent statin drugs on the market.
The test, known as high-sensitivity C-reactive protein test, requires a blood sample and costs about $25.
CRP is a measure of inflammation in the body. It can be increased by a lot of risk factors, including being overweight and smoking, or even temporary conditions such as an infection.
The study involved an analysis of 15,548 people who were part of a two-year clinical trial comparing 20 milligrams of Crestor with a placebo. The trial was funded by AstraZeneca, the maker of the drug. Doctors not associated with the trial said the finding is likely to lead to a change in guidelines that will vastly broaden the use of CRP testing. The research "suggests that inflammation is important, independent of your cholesterol," said Michael Widlansky, an assistant professor of medicine and pharmacology at the Medical College of Wisconsin and a cardiologist at Froedtert Hospital. "These are typical Americans." The study found a 65% reduction in so-called vascular events such as heart attacks, strokes, cardiovascular deaths or the need for a heart procedure in those who got their CRP and LDL cholesterol down to low levels, compared with a 33% reduction in those who got one or neither of the two measures below a targeted level. The targets were aggressive: LDL cholesterol of less than 70 milligrams per deciliter and CRP of less than 2 milligrams per liter. While people in the study had acceptable LDL cholesterol levels, most of them had other conditions that increased their heart disease risk, said James Stein, a cardiologist at the University of Wisconsin-Madison's School of Medicine and Public Health. Those conditions included their age, being overweight and having slightly elevated blood pressure.
"It's very uncommon to find high CRP in the absence of something else," Stein said. Still, he said, the test provides "one simple number" that can be used to let people know more about their risk. The study's authors noted that lifestyle interventions such as diet, exercise and smoking cessation should be tried before putting someone on a statin such as Crestor, which costs about $100 a month. Indeed, generic statins, which cost a fraction of that, also are likely to bring about substantial reductions in both LDL cholesterol and CRP, doctors said. "All statins lower LDL, and all statins lower CRP," said the study's lead author, Paul Ridker, director of the Center for Cardiovascular Disease Prevention at Brigham and Women's Hospital in Boston. "Compliance with taking any statin is far more important than which one." Ridker and the hospital jointly hold patents on CRP testing that have been licensed to AstraZeneca.
