Blink_ The Power of Thinking Without Thinking - Malcolm Gladwell [50]
A patient comes in clutching his chest. A nurse takes his blood pressure. A doctor puts a stethoscope on his chest and listens for the distinctive crinkling sound that will tell her whether the patient has fluid in his lungs — a sure sign that his heart is having trouble keeping up its pumping responsibilities. She asks him a series of questions: How long have you been experiencing chest pain? Where does it hurt? Are you in particular pain when you exercise? Have you had heart trouble before? What’s your cholesterol level? Do you use drugs? Do you have diabetes (which has a powerful association with heart disease)? Then a technician comes in, pushing a small device the size of a desktop computer printer on a trolley. She places small plastic stickers with hooks on them at precise locations on the patient’s arms and chest. An electrode is clipped to each sticker, which “reads” the electrical activity of his heart and prints out the pattern on a sheet of pink graph paper. This is the electrocardiogram. In theory, a healthy patient’s heart will produce a distinctive — and consistent — pattern on the page that looks like the profile of a mountain range. And if the patient is having heart trouble, the pattern will be distorted. Lines that usually go up may now be moving down. Lines that once were curved may now be flat or elongated or spiked, and if the patient is in the throes of a heart attack, the ECG readout is supposed to form two very particular and recognizable patterns. The key words, though, are “supposed to.” The ECG is far from perfect. Sometimes someone with an ECG that looks perfectly normal can be in serious trouble, and sometimes someone with an ECG that looks terrifying can be perfectly healthy. There are ways to tell with absolute certainty whether someone is having a heart attack, but those involve tests of particular enzymes that can take hours for results. And the doctor confronted in the emergency room with a patient in agony and another hundred patients in a line down the corridor doesn’t have hours. So when it comes to chest pain, doctors gather as much information as they can, and then they make an estimate.
The problem with that estimate, though, is that it isn’t very accurate. One of the things Reilly did early in his campaign at Cook, for instance, was to put together twenty perfectly typical case histories of people with chest pain and give the histories to a group of doctors — cardiologists, internists, emergency room docs, and medical residents — people, in other words, who had lots of experience making estimates about chest pain. The point was to see how much agreement there was about who among the twenty cases was actually having a heart attack. What Reilly found was that there really wasn’t any agreement at all. The answers were all over the map. The same patient might be sent home by one doctor and checked into intensive care by another. “We asked the doctors to estimate on a scale of zero to one hundred the probability that each patient was having an acute myocardial infarction [heart attack] and the odds that each patient would have a major life-threatening complication in the next three days,” Reilly says. “In each case, the answers we got pretty much ranged from zero to one hundred. It was extraordinary.”
The doctors thought they were making reasoned judgments. But in reality they were making something that looked a lot more like a guess, and guessing, of course, leads to mistakes. Somewhere between 2 and 8 percent of the time in American hospitals, a patient having a genuine heart attack gets sent home — because the doctor doing the examination thinks for some reason that the patient is healthy. More commonly, though, doctors correct for their uncertainty by erring heavily on the side of caution. As long as there is a chance that someone might be having a heart attack, why take even the smallest risk by ignoring her problem?
“Say you’ve got a patient who presents to ER complaining of severe chest pain,” Reilly says. “He’s old and he smokes and he has high blood pressure.