Monday, September 14, 2009

How We Decide by Jonah Lehrer P. 163-165

In chapter 5 of his book, How We Decide, Jonah Lehrer discusses back pain and what changed after the MRI became a "crucial medical tool. It allowed doctors to look, for the first time, at stunningly accurate images of the interior of the body.” Unfortunately without a proper context including a much better understanding of the human body, this ‘accurate evidence’ gave them a false confidence in their decisions. This appears to have resulted in lots of unnecessary tests, procedures and surgeries.

p. 163-164 How we Decide

“A large study published in the Journal of the American Medical Association (JAMA) randomly assigned 380 patients with back pain to undergo two different types of diagnostic analysis. One group received x-rays. The other group got diagnosed using MRIs, which gave doctors much more information about the underlying anatomy.

Which group fared better? Did better pictures lead to better treatments? There was no difference in patient outcome: the vast majority of people in both groups got better. More information didn't lead to less pain. The stark differences emerge when the study looked at how the different groups were treated. Nearly 50% of MRI patients were diagnosed with some sort of disc abnormality, and this diagnosis led to intensive medical interventions. The MRI group had more doctor visits, more injections, more physical therapy, and were more than twice as likely to undergo surgery. These additional treatments were very expensive, and they had no measurable benefit.”

I posted a video yesterday of Nassim Taleb, saying the same thing about certain financial metrics: the (false) precision of the measure gives a trader or bank executive a false understanding of the risk being taken and a false confidence in his/her understanding.

p. 165 How we Decide

“The problem with diagnosing the origins of back pain is really just another version of the strawberry-jam problem*. In both cases, the rational methods of decision-making cause mistakes. Sometimes, more information and analysis can actually constrict thinking, making people understand less about what's really going on. Instead of focusing on the most pertinent variable -- the percentage of patients who get better and experienced less pain -- doctors got sidetracked by the irrelevant MRI pictures.

When it comes to treating back pain, this wrong-headed approach comes with serious costs. "What's going on now is a disgrace," says Dr. John Sarno, a professional of clinical rehabilitation at New York University Medical Center. "You have well-meaning doctors making structural diagnoses despite a serious lack of evidence that these abnormalities are really causing chronic pain. But they have these MRI pictures and the pictures seem so convincing. It's amazing how perfectly intelligent people will make foolish decisions if you give them lots of irrelevant stuff to consider."

*Strawberry Jam problem: in blind taste tests, students’ tastes correlated with a panel of experts, but when asked to explain their decisions, another group of students showed no correlation. i.e there are situations when rational-decision making causes worse decisions.

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