Absolute risk versus relative risk

Here is a short article that discusses the topic of absolute risks focusing on the now withdrawn drug, Vioxx.  

My own highly speculative opinion is that Merck withdrew Vioxx rather than heavily publicize the absolute risk numbers because it understood that if  the public became aware of the importance of absolute risk and benefit statistics it would ultimately hurt profits more.

Why? Well, because stated in terms of absolute benefit, very few drugs are worth the cost and the bother.

Please read this carefully as even in professional circles the concepts of absolute vs relative risk and benefit statistics not understood well.

from Cardiobrief:

Posted on May 7, 2010 by Larry Husten

There’s a fascinating discussion about Vioxx echoing around the blogosphere. (William Heisel has a nice summary here.) A few weeks ago Catherine DeAngelis, the editor of JAMA, spoke at the recent meeting of the Association of Health Care Journalists and said:

I believe Vioxx should not have been taken off the market. At least a million people, if told the truth about its side effects, would accept it because their lives could be lived with a lot less pain. There are a lot of people now whose lives are miserable because they have to live with arthritic pain.

At the same meeting, the editor of Reuters Health, Ivan Oransky, was critical of the way the Vioxx issue was reported by many journalists: “There was a doubling of heart attack risk, but the doubling was from a 1% risk to a 2% risk. If you lay that all out to readers, they can make much better decisions.”

I think DeAngelis and Oransky make valid points, but I think they miss a much more important point.

DeAngelis of course is right: there are probably a million people who even now would be willing to make the calculated risk and take Vioxx. The problem is that not only were those 1 million people never told about the risk, there were another 19 million people taking the drug as a first line analgesic who were extremely unlikely to derive any unique benefit from the drug and who never should have been started on the drug in the first place. In a carefully selected patient population the risk to benefit equation yields very different results than in an indiscriminate population 20 times the size.

Let’s assume Oransky’s and DeAngelis’s numbers are true. (It’s the general concept, not the actual numbers, that are important here.) If a million patients took Vioxx then the number of heart attacks doubled from 10,000 to 20,000. That seems like a lot, but if all these people were deriving significant pain relief from Vioxx, after having failed previous agents, then perhaps the excess risk could be deemed worthwhile.

But if 20 million people were taking Vioxx then the number of heart attacks jumps from 200,000 to 400,000, although only 1 million people are likely to derive any benefit from the drug. Suddenly the small increase in absolute risk is pretty frightening…

find the rest via Vioxx, Avandia, Vytorin: absolute risk versus relative risk « CardioBrief.

here is a link to William Heisel’s most recent post on this subject

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