Interpreting the data

Monday, November 10, 2008

When it comes to research, the devil is in the details and those details sometimes get lost when science makes it to the front page. The announcement that healthy people can cut their heart attack risk in half by taking a cholesterol lowering drug made headlines around the world.

Researchers presented a study at the American Heart Association annual meeting and simultaneously published it in the New England Journal of Medicine that described the positive effects of Crestor, a drug used to lower cholesterol. Normally the medication would be used to bring cholesterol levels into the normal range and prevent one of the risk factors for heart disease and stroke. In this study, almost 18,000 healthy people from different countries around the world were monitored for almost two years to see whether Crestor would prevent heart attack and stroke. These patients didn’t have high blood pressure, diabetes or liver disease but they did have an abnormal blood test called C – reactive protein (CRP) which is marker in the blood that there is inflammation in the body. Elevated CRP levels may indicate inflammation in the heart arteries and can be used as a screening test for heart attack risk.

Newspapers, television and internet headlines touted the 44% reduction in heart disease, from heart attack to death. The study authors heralded a new age in heart attack prevention, but nothing in medical research is easy and sometimes it’s important to step back, take a deep breath and as Paul Harvey is wont to say: read the rest of the story.

There were 18,000 people enrolled in the study including men over 50 and women over 60; half took Crestor, half took a placebo. Though the study was supposed to last 4 years, it was stopped just shy of 2 years because the early numbers looked so good and the people overseeing the study, felt that they could not ethically withhold Crestor from the placebo group.

157 people in the placebo group died of stroke, heart attack or another heart illness. Only 83 died in the group taking Crestor. The number looks better when expressed as a percentage. The risk was cut by 44%. It’s less impressive when it is expressed as 73 patients out of 18,000. It would cost almost $290,000 in medication alone to save one life.

Aside from the numbers, a couple other issues need to be addressed. It isn’t known what happens to people with normal cholesterol who take Crestor for long periods of time. A two year study isn’t very long when a 50 year old may take it for 30 or 40 years. And there isn’t any consensus yet how to use CRP as useful screening tool to decide who gets the drug and who doesn’t.

Finally, an ethical issue that probably isn’t but at least needs to be addressed. The lead author of the study, Dr. Paul Ridker and his hospital, Brigham and Womens Hospital, own the patent for the C Reactive Protein test and have licensed it to the pharmaceutical company, Astra Zeneca, the same company that manufactures Crestor.

It may be that the headlines will stand the test of time but before patients are encouraged to rush to their family doctor and demand a blood test and new prescription, perhaps it would be wise to wait and see the details that emerge in the near future. Just like any other consumer behavior, there will be those who will rush out and buy the latest and greatest technology while others will wait and allow the bugs to be worked out.

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