A Better Way to Screen for Heart Disease?
Research suggests that using statins to lower CRP levels might save lives
The Jupiter trial found that being on a statin cut high CRP levels by 37 percent—which, to Ridker, suggests that screening for CRP should be much more widely used in heart disease risk assessment. (He helped invent the test, called "high-sensitivity CRP," and receives royalties from its sale.) Still, Ridker concedes that concluding that lowering an elevated CRP level directly benefits the arteries would be based on faith, rather than evidence. The American Heart Association says this "hasn't yet been established" and recommends thehs-CRP test only for intermediate-risk patients—those whose age, gender, cholesterol levels, blood pressure, and smoking habits translate as a 10 to 20 percent risk of heart attack over the next 10 years. (About half of the Jupiter participants had less than a 10 percent heart disease risk.) "The study doesn't totally clarify the causal role of CRP in the development of cardiac events," says AHA's president, Timothy Gardner.
One confounding factor in Jupiter, experts point out, is that the drug used to lower inflammation—rosuvastatin, manufactured by AstraZeneca (which funded the study)—also dramatically lowered levels of harmful LDL cholesterol. Siscovick says this leaves open the question of whether the benefits were largely due to the statin's cholesterol-lowering effects, even though participants' LDL levels weren't elevated. Schwartz concurs and wonders whether a drug that targets only inflammation, like aspirin, might have worked as well as a statin in people without obvious heart disease.
Still, given the edge that statins demonstrated over placebos, why not make CRP screening as routine as cholesterol and blood pressure checks? After all, Schwartz estimates that half of American adults would be flagged as having high levels, defined by the Jupiter study as more than 2 mg per liter of blood. Trouble is, she says, this could swell the ranks of people on statins by millions. The drugs are considered to be very safe, but they do have side effects, such as disabling muscle pain. In rare cases, they elevate liver enzymes and cause severe muscle deterioration and kidney malfunction. While the Jupiter trial didn't detect a significant increase in these problems, Ridker admits that the study size may not have been large enough to detect unusual complications. And for reasons that aren't clear, the people taking statins were slightly more likely to develop diabetes during the study than the placebo group.
As doctors and public-health experts tussle over whether to look for and treat inflammation more aggressively, ordinary folks can act now to make some inflammation-fighting lifestyle changes. The Jupiter participants, with a typical CRP level of 4 mg per liter, weren't exactly the picture of health: Most of them were overweight, and many had metabolic syndrome, a precursor of diabetes that is characterized by high blood-sugar levels, too much abdominal fat, and high blood pressure, for example. Some were smokers. If this sounds like you, you probably have increased inflammation, too. A growing body of evidence suggests approaches beyond statins also lower CRP levels:
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