June 23, 2012

MARKETING, NOT MEDICINE:

The Problem Is Relative (H. Gilbert Welch, 06/21/2012, Huffington Post)

A few years ago a study of a cholesterol-lowering statin drug was hailed for big reductions in heart attacks in people with so-called healthy cholesterol levels. The drug led to about a 50 percent reduction in the risk of heart attack. That sounds like a breakthrough.

But the absolute risks -- the real numbers -- are sure to look a little different. Why? Because in people with healthy cholesterol levels, heart attacks are rare. To get that context, get the two additional numbers: the risk of heart attack in people taking and not taking the drug.

For people taking the drug, the chance of having a heart attack over five years was less than 1 percent. To be sure, that is about 50 percent lower than the analogous risk for those not taking the drug -- less than 2 percent -- but it sounds a lot less like a breakthrough.

These absolute risks suggest that 100 apparently healthy people have to take the medication for five years for one to avoid a heart attack. And it's not even clear from the research -- or the federal registry of clinical trials -- what kind of heart attack: the kind that patients experience (the bad kind) or the kind that is diagnosed by detecting less than a billionth of gram of a protein in the blood (the not-so-important kind). Add in all the hassle factors of being on another drug (filling scripts, blood tests, insurance forms) and the legitimate concerns about side effects, the use of relative change might now strike you as more than a little misleading.

Whatever the finding -- harm or benefit -- relative change exaggerates it.

Upon learning this, one of my students likened relative change to funhouse mirrors. If you are thin, there is a mirror that can make you look too thin; if you are heavy, there is mirror that can make you look too heavy.

In the case of relative change, it all happens in the same mirror. It provides a potent combo to promote medical care: exaggerated perceptions of risk and exaggerated perceptions of benefit. Can you imagine a more powerful marketing strategy?

Posted by at June 23, 2012 6:24 AM
  

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