Monday, May 2, 2016

The Medical Bait and Switch

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I just discovered a thinking fallacy featured in the book "Superforecasting." It happens all the time in medicine.

It's called the bait and switch. It's similar to anchoring, but different.

It happens when, confronted with a difficult and foreign problem, a person substitutes an easier-to-solve and more intuitive problem, and then answers that problem. 

When someone comes to the emergency room with shortness of breath, this is a complex problem with many, many possible causes, often mixed together. Rather then get to the bottom of this, we substitute shortness of breath with a simpler problem- pulmonary edema from heart failure. Mild pulmonary edema is a much easier problem than shortness of breath. We give a relatively harmless medicine, furosemide, quantify that we're making progress by measuring its effect on weight loss or negative fluid balance, and then dust our hands of the problem and congratulate ourselves on another job well done. 

Meanwhile, while hospitalized for a few days, the patient is removed from whatever insult caused the shortness of breath (maybe the mold in their apartment triggers asthma, or the challenges of insecure housing, nutrition or basic safety, or substance use). During that remove, they feel better and their shortness of breath improves. 

They feel especially better when suggested by their doctors' leading query: "Are you feeling better?" 

This is even more effective when phrased like "You've lost a liter of fluid and your chest X-ay is clear, are you breathing better?" Who could say no?

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