Crestor is considered to be one of the most powerful of the statins. Its maximum 40-milligram dose is half of the maximum approved for other popular statins, such as Pfizer Inc.'s Lipitor and Merck & Co.'s Zocor.
Safety concerns have dogged Crestor since it was approved in 2003. A variety of studies have come to conflicting conclusions on the drug's safety.
Crestor's 40-milligram dose is recommended only for those who don't meet their cholesterol goals on lower doses. The product label cautions patients to weigh the possible risks of muscle damage against the potential benefits. Researchers said no cases of severe muscle damage were reported in the study. Nineteen patients, or 3.7%, quit the study complaining about muscle pain and weakness.
Asians are advised to take no more than 20 milligrams because of poorly understood genetic factors.
Dr. Sidney Wolfe of the Washington watchdog group Public Citizen said he was concerned that the study would lead to increased prescribing of the highest dose of Crestor.
In an editorial published online Monday by the Journal of the American Medical Assn., Dr. Roger S. Blumenthal of Johns Hopkins Medical School said the study also did not address whether the highest dose of Crestor was needed to reduce blockages.
Nissen said that it would have been unethical to give heart disease patients a placebo or lower dosages. He also said that a study that compared Crestor with another drug would have been expensive and it was unlikely that a drug company would fund such a trial because of the risk of its drug looking bad.
Another unanswered question is what happens to blockages when patients take high doses of cholesterol drugs for longer periods.
"If we continued for five years instead of two, could we get to 50 [milligrams]?" Nissen said. "How much plaque could we get rid of? How far can we turn back the clock on disease?"