The findings may also lead to a more important role for the blood test high-sensitivity C-reactive protein (hsCRP) in assessing cardiovascular risk.
The study included about 18,000 apparently healthy men and women with normal cholesterol but higher than normal levels of high sensitivity C-reactive protein, a marker of inflammation that has been linked to heart disease.
Originally planned as a four-year trial, the study was stopped late in March after most participants had taken the statin for less than two years.
People who took Crestor had half as many major cardiovascular events as people assigned to the placebo arm of the trial.
The study was funded by Astra-Zeneca, which makes Crestor. It was presented in New Orleans at the American Heart Association's Scientific Sessions and it also appears in the Nov. 20 issue of The New England Journal of Medicine.
"Physicians can no longer assume that a patient with low cholesterol has a low risk for a heart attack or stroke," lead researcher Paul M. Ridker, MD, of Boston's Brigham and Women's Hospital, tells WebMD.
Statins Benefit "Low-Risk" Patients
Statins are generally prescribed only for people with high cholesterol or those who have borderline high cholesterol and other risk factors for heart attack and stroke, such as diabetes or established heart disease.
The newly reported trial was designed to explore whether statins might also benefit these people.
All of the study participants had LDL cholesterol levels of less than 130 milligrams per deciliter when they entered the trial, and none had known diabetes or heart disease. But they did have high-sensitivity CRP levels of 2.0 milligrams per liter or higher.
Blood hsCRP levels of less than 1 milligram per liter are indicative of low cardiovascular risk, while 1 to 3 milligrams per liter indicates moderate risk, and greater than 3 indicates high risk, Ridker says.
About 9,000 study participants were treated with 20 milligrams per day of Crestor and an equal number of participants took a placebo.
When the trial was stopped after a median follow-up of 1.9 years, statin users had lowered their LDL cholesterol by an average of 50% and their hsCRP by 37%.
There were also half as many heart attacks, strokes, and deaths from cardiovascular causes among the participants taking the statin. In all, 0.9% of statin users had one of these events, compared to 1.8% of placebo users.
"This study was designed to identify new groups of patients who could benefit from statin therapy, and it did that," Mayo Clinic cardiologist and American Heart Association past-president Raymond Gibbons, MD, tells WebMD. "There is no question that these findings are robust, but there are still unanswered questions about who should take these drugs."
Stanford University professor of health research and policy Mark A. Hlatky, MD, agrees.
In an editorial published with the study, Hlatky wrote that it is still not clear if the benefits of treating relatively low-risk people with statins for many decades outweigh the risks.
He notes that 120 people with similar risk factors to the people in the study would have to be treated for 1.9 years to prevent one heart attack, stroke, or death from cardiac causes.
The Crestor-treated participants were also slightly more likely to be diagnosed with diabetes during the study than placebo-treated participants.
"We are talking about treating relatively low-risk people with a drug that they will take for the rest of their lives," he tells WebMD. "We can't just say everyone should be treated. Individual risk factors need to be considered."
Expanded Role for hsCRP?
The study raises important questions about the role of high-sensitivity CRP in assessing cardiovascular risk.
The test is increasingly used by cardiologists but has not been considered a routine test for heart disease risk, mainly because its impact on treatment decisions has not been clear.
These findings, along with two other studies presented this weekend in New Orleans, could change this.
The studies, supported by the National Heart, Lung, and Blood Institute (NHLBI), showed the hsCRP test to be valuable for evaluating risk after a first heart attack or stroke.
In a written statement, NHLBI Director Elizabeth G. Nabel, MD, notes that the three studies provide the strongest evidence so far that hsCRP testing is a useful marker for cardiovascular disease.
"Many clinicians now offer hsCRP testing to their patients, but until now the value of hsCRP levels to treatment decisions, especially in adults with desirable cholesterol levels, was unclear," she writes.
An expert NHLBI-led panel is reviewing the scientific evidence regarding hsCRP testing and is expected to make more specific recommendations on how the test should be used in its revised guidelines for lowering cardiovascular disease risk.