2008
10.30
10.30
The sister of a friend of mine in India suffered from Crohn’s disease, a disease of the digestive system that is rare amongst Asians. Her condition was misdiagnosed for several years, causing her an immense amount of suffering. I have another friend who’s wife is suffering from something that has not been identified yet. Every doctor seems to think something else is wrong and she’s subject to a different treatment each time. Even temporary relief is rare.
Studies based on autopsies indicate that 10-15% of diagnosis are wrong. What are the causes of these failures of diagnosis ? Is it that the condition is really rare such as in the case of Crohn’s disease that it is difficult for the doctors to know or is it something else ? Come to think of it, how do doctors think their way to a diagnosis ? And why is it that many times, two different doctors disagree on the diagnosis ? What if I were a drunk or if I was obese ? Does my doctor emotionally react to my state (in disgust, for example) or don’t they ? If they do, how does that color their care ? What if they were positively affected by my condition, seeing me fit, in good condition, articulate and well mannered ? Does their positive thinking about me negatively affect my care ?
How Doctors Think by Dr. Jerome Kroopman is a book that addresses these questions. Dr. Kroopman, himself a physician and a professor at Harvard Medical School, has written a brilliant, lucid and engrossing book that addresses the very nature of how doctors think. That our thinking is fraught with myriad cognitive biases is well accepted now. This book illustrates how those errors are at the heart of incorrect diagnosis and the conditions that cause them.
Dr. Kroopman says that experts studying misdiagnosis that caused serious harm to patients attribute most errors to errors in thinking, not to lack of medical knowledge. He quotes one study that attributed 80% of misdiagnosis to cognitive errors, and another study that parceled inadequate medical knowledge to only 4% of the cases. About 15% of all diagnosis were incorrect says a 1995 report in which doctors provided a diagnosis based on written descriptions of the patient’s symptoms and examined actors simulating patients with various diseases. The average diagnostic error in interpreting medical images (such as XRays, CAT scans and MRI) is about 20-30%, an alarmingly large number. In a study assessing 100 radiologists on chest x-rays, they disagreed amongst themselves 20% of the time, when asked the same question a few days later after studying the same x-ray again, they disagreed with themselves 5-10% of the time. 60% of them failed to identify a missing clavicle. But cuing them saying that these x-rays were part of identifying cancer, 83% of them identified the missing clavicle, when told that it was part of an annual physical, 58% missed the finding.
Over the course of 320 pages and 10 chapters, Dr. Kroopman looks at different kinds of doctors from ER physicians to family practitioners to pediatricians to radiologists to specialists and brings a keen eye to the nuances of each profession, their difficulties and their practices and how cognitive errors enter the diagnostic process. In an era where doctors find themselves squeezed by money on either end, by big money pharma on one end and by the insurance industry at the other end, the book also addresses the kinds of cognitive errors that result, in part, by the the role of these two major ecosystem players.
The Cognitive Errors
Dr. Kroopman runs through the gamut of cognitive biases as he follows the minds of doctors during the course of their making a diagnosis. Many of these cognitive biases amplify each other resulting in a decision that seems rock solid to the physician but is not.
When a doctor sends a request to a radiologist asking for a check of the lungs for checking lung cancer, that question makes the radiologist think in a particular way, about lung cancer as opposed to say pneumonia. Or at other times, a doctor may send a patient to a specialist with a statement such as “I’m sending you a case of renal failure and diabetes”. Forcing doctors to think about particular outcomes makes them not think about certain others. This creates the framing error. A simple joke illustrates the framing error. Two friends go to a church for praying and one of them gets an urge to smoke. He decides to check with the priest before smoking. He asks the padre, “Father, is it OK to smoke while I pray” to which the father responds with utter horror and chastises him. When he reports the result to his friend, his friend says that he asked the wrong question and proceeds to ask, “Father, is it OK to pray while I smoke” to which the padre gushes, “My son, it is always OK to pray when you’re doing anything”. The first question activated the “smoking” frame and the second, the “praying” frame. The annual physical versus the cancer example quoted at the start of this article is a more pertinent and troubling example of the framing error.
A pediatrician seeing a stream of cranky children with fever who have the flu can easily overlook the one exception with meningitis. A doctor in India seeing a patient with diarrhea, vomiting and abdominal pain is more likely to consider irritable bowel syndrome rather than Crohn’s disease because that is the common case and Crohn’s is hardly seen. In other words, the brain arrives at a specific conclusion (or set of conclusions) based on the information that is easily available and we implicitly assume that “if we can think of it, it must be important”. This is called availability error. If I asked you if there are more number of words that start with the letter t compared to words which have t as the third letter, you’re more likely to think that it’s the former because of the ease with which you can come up with words that start with the letter t.
Once we’ve arrived at a conclusion, we tend to selectively look for data that confirm our conclusion and ignore or reinterpret the rest. This is called confirmation bias. Ego is a big factor here since we like to think of ourselves as more competent than we really are. Various studies show that the more incompetent we are, the more certain we tend to act (Sarah Palin effect ?). One example that Dr. Kroopman points to is a study comparing 100 radiologists in which the bottom twenty were more confident than the top twenty.
In another anecdote, a doctor looking for the cause of a persistent ache in the hand concludes that the cause are cysts in the hand when the problem was something else altogether. Search satisficing is caused by our stopping to look for causes once we’ve settled on one. For example, if you’re rushing to the airport and realize you’re missing your wallet, you start searching for it desperately; once you find it, elated, you rush out of the house, only to realize much later that you’ve forgotten the plane ticket inside. Having seen the cysts, the doctor stopped looking for other causes. Dr. Kroopman quotes a physician, “”Finding something maybe satisfactory, but not finding everything is suboptimal”.
Anchoring is another reason for search satisficing. In an experiment, participants were asked about the percentage of African nations that were members of the UN. They asked one group whether the percentage was more or less than 45% and they asked the other group if the percentage was more or less than 65%. Each group tended to anchor their answer around the number quoted to them, 45% or 65%. The doctor who arrived at the cysts as the answer, weighted his diagnosis by anchoring his decision on the importance of cysts.
Many of these errors are also caused by attribution error, especially if the patient is associated with negative stereotypes. Dr. Kroopman provides the anecodote of a patient who comes to a doctor after a decade of illness with labels of “anorexic” and “psychiatric” and how those labels helped many doctors give the patient a short shrift, arriving at a diagnosis rather quickly. Similarly, a doctor seeing a very personable, older patient may demur from subjecting him to a more invasive test that would really clear that little lingering uncertainty about the diagnosis.
Commission bias is caused because of the very nature of the medical profession (nay, the Western culture). It is the desire to act instead of observe. “Don’t just stand there, do something” is the Western mantra. Dr. Kroopman points to surgeons as examples of people with this bias.
The Conditions
All these cognitive biases are heuristics that we resort to when we’re in a hurry. Most of these biases can be overcome by pondering. But in an age where pediatricians and general practitioners attempt to remedy their lowering reimbursements from HMOs by seeing more patients, ponder is something they cannot do. And in places like ER, the very nature of what they do forces the physicians to work quickly. One ER physician is quoted as saying that he feels like a circus juggler, spinning plates on a stick; slowing down will cause everything to crash. Similarly, a primary care physician is quoted as saying that looking for the out of the ordinary gets very hard because she feels like someone looking for a face in a passing train; if the train goes faster and faster or if you get distracted, you can easily miss that face. Dr. Kroopman states that on the average, a radiologist views 150 CAT scans over a weekend and a CAT scan has dozens of images; new technologies such as MRI produce hundreds of images. Scanning them visually looking for errors takes time and time is always pressing (on the other hand, a radiologist who looks at an image for more than 38 seconds, risks seeing things that aren’t there).
Physicians also have to walk a balancing act between raising unnecessary fears and ignoring real problems. Learning how to communicate becomes a key factor. Dr. Kroopman says that there is a myth that a brilliant doctor is a poor communicator and a good communicator is a poor doctor. Both are essential, he says. A good doctor is one who communicates well, listens and speaks. The kinds of questions (s)he asks can result in a diagnosis arrived at through a stream of cognitive errors. Most of us are afraid and anxious when we visit a doctor, we also don’t want to appear stupid, as somebody wasting the doctor’s time. If we perceive the doctor is rushed or don’t get asked the right set of questions, we may not provide the information necessary to arrive at the right diagnosis. A study found that on average, a doctor interrupts a patient 18 seconds after the patient first starts telling their story.
Dr. Kroopman also says that much of what doctors practice is a result of where and under whom they studied. Shanthala tells me of procedures that were insisted on in her MD program that the hospital where she works don’t insist and instead do it slightly differently. “Playing God” is a familiar term used to describe doctors. Part of that allure is the mask of certainty that most doctors exude. Dr. Kroopman says that the orthodox and conservative medical establishment fosters such attitudes.
What Can We Do
Reading books like this can leave us wondering if there’s anything we can do. Fortunately, Dr. Kroopman offers lots of suggestions, questions that we can ask to jar the doctor out of their heuristics. For example, we can ask what organs are around where we’re having the problem forcing the doctor to consider other possibilities than gall stones. Or we could ask the doctor to compare the lingering pain post-surgery to having a tooth pulled to get more specific answers. He even helpfully summarizes all these questions in a single epilogue.
Dr. Kroopman addresses these and much more in a book filled with real life anecdotes, many from his own life, both as a doctor and as patient; most of the cases are real cliff hangers. He rarely casts a jaundiced eye on either the doctor, the system or the patient, though he does sound skeptical about the current health care system with insurance companies and big pharma calling the shots. Overall, a very knowledgable and pleasurable read. Highly recommended.
Studies based on autopsies indicate that 10-15% of diagnosis are wrong. What are the causes of these failures of diagnosis ? Is it that the condition is really rare such as in the case of Crohn’s disease that it is difficult for the doctors to know or is it something else ? Come to think of it, how do doctors think their way to a diagnosis ? And why is it that many times, two different doctors disagree on the diagnosis ? What if I were a drunk or if I was obese ? Does my doctor emotionally react to my state (in disgust, for example) or don’t they ? If they do, how does that color their care ? What if they were positively affected by my condition, seeing me fit, in good condition, articulate and well mannered ? Does their positive thinking about me negatively affect my care ?
How Doctors Think by Dr. Jerome Kroopman is a book that addresses these questions. Dr. Kroopman, himself a physician and a professor at Harvard Medical School, has written a brilliant, lucid and engrossing book that addresses the very nature of how doctors think. That our thinking is fraught with myriad cognitive biases is well accepted now. This book illustrates how those errors are at the heart of incorrect diagnosis and the conditions that cause them.
Dr. Kroopman says that experts studying misdiagnosis that caused serious harm to patients attribute most errors to errors in thinking, not to lack of medical knowledge. He quotes one study that attributed 80% of misdiagnosis to cognitive errors, and another study that parceled inadequate medical knowledge to only 4% of the cases. About 15% of all diagnosis were incorrect says a 1995 report in which doctors provided a diagnosis based on written descriptions of the patient’s symptoms and examined actors simulating patients with various diseases. The average diagnostic error in interpreting medical images (such as XRays, CAT scans and MRI) is about 20-30%, an alarmingly large number. In a study assessing 100 radiologists on chest x-rays, they disagreed amongst themselves 20% of the time, when asked the same question a few days later after studying the same x-ray again, they disagreed with themselves 5-10% of the time. 60% of them failed to identify a missing clavicle. But cuing them saying that these x-rays were part of identifying cancer, 83% of them identified the missing clavicle, when told that it was part of an annual physical, 58% missed the finding.
Over the course of 320 pages and 10 chapters, Dr. Kroopman looks at different kinds of doctors from ER physicians to family practitioners to pediatricians to radiologists to specialists and brings a keen eye to the nuances of each profession, their difficulties and their practices and how cognitive errors enter the diagnostic process. In an era where doctors find themselves squeezed by money on either end, by big money pharma on one end and by the insurance industry at the other end, the book also addresses the kinds of cognitive errors that result, in part, by the the role of these two major ecosystem players.
The Cognitive Errors
Dr. Kroopman runs through the gamut of cognitive biases as he follows the minds of doctors during the course of their making a diagnosis. Many of these cognitive biases amplify each other resulting in a decision that seems rock solid to the physician but is not.
When a doctor sends a request to a radiologist asking for a check of the lungs for checking lung cancer, that question makes the radiologist think in a particular way, about lung cancer as opposed to say pneumonia. Or at other times, a doctor may send a patient to a specialist with a statement such as “I’m sending you a case of renal failure and diabetes”. Forcing doctors to think about particular outcomes makes them not think about certain others. This creates the framing error. A simple joke illustrates the framing error. Two friends go to a church for praying and one of them gets an urge to smoke. He decides to check with the priest before smoking. He asks the padre, “Father, is it OK to smoke while I pray” to which the father responds with utter horror and chastises him. When he reports the result to his friend, his friend says that he asked the wrong question and proceeds to ask, “Father, is it OK to pray while I smoke” to which the padre gushes, “My son, it is always OK to pray when you’re doing anything”. The first question activated the “smoking” frame and the second, the “praying” frame. The annual physical versus the cancer example quoted at the start of this article is a more pertinent and troubling example of the framing error.
A pediatrician seeing a stream of cranky children with fever who have the flu can easily overlook the one exception with meningitis. A doctor in India seeing a patient with diarrhea, vomiting and abdominal pain is more likely to consider irritable bowel syndrome rather than Crohn’s disease because that is the common case and Crohn’s is hardly seen. In other words, the brain arrives at a specific conclusion (or set of conclusions) based on the information that is easily available and we implicitly assume that “if we can think of it, it must be important”. This is called availability error. If I asked you if there are more number of words that start with the letter t compared to words which have t as the third letter, you’re more likely to think that it’s the former because of the ease with which you can come up with words that start with the letter t.
Once we’ve arrived at a conclusion, we tend to selectively look for data that confirm our conclusion and ignore or reinterpret the rest. This is called confirmation bias. Ego is a big factor here since we like to think of ourselves as more competent than we really are. Various studies show that the more incompetent we are, the more certain we tend to act (Sarah Palin effect ?). One example that Dr. Kroopman points to is a study comparing 100 radiologists in which the bottom twenty were more confident than the top twenty.
In another anecdote, a doctor looking for the cause of a persistent ache in the hand concludes that the cause are cysts in the hand when the problem was something else altogether. Search satisficing is caused by our stopping to look for causes once we’ve settled on one. For example, if you’re rushing to the airport and realize you’re missing your wallet, you start searching for it desperately; once you find it, elated, you rush out of the house, only to realize much later that you’ve forgotten the plane ticket inside. Having seen the cysts, the doctor stopped looking for other causes. Dr. Kroopman quotes a physician, “”Finding something maybe satisfactory, but not finding everything is suboptimal”.
Anchoring is another reason for search satisficing. In an experiment, participants were asked about the percentage of African nations that were members of the UN. They asked one group whether the percentage was more or less than 45% and they asked the other group if the percentage was more or less than 65%. Each group tended to anchor their answer around the number quoted to them, 45% or 65%. The doctor who arrived at the cysts as the answer, weighted his diagnosis by anchoring his decision on the importance of cysts.
Many of these errors are also caused by attribution error, especially if the patient is associated with negative stereotypes. Dr. Kroopman provides the anecodote of a patient who comes to a doctor after a decade of illness with labels of “anorexic” and “psychiatric” and how those labels helped many doctors give the patient a short shrift, arriving at a diagnosis rather quickly. Similarly, a doctor seeing a very personable, older patient may demur from subjecting him to a more invasive test that would really clear that little lingering uncertainty about the diagnosis.
Commission bias is caused because of the very nature of the medical profession (nay, the Western culture). It is the desire to act instead of observe. “Don’t just stand there, do something” is the Western mantra. Dr. Kroopman points to surgeons as examples of people with this bias.
The Conditions
All these cognitive biases are heuristics that we resort to when we’re in a hurry. Most of these biases can be overcome by pondering. But in an age where pediatricians and general practitioners attempt to remedy their lowering reimbursements from HMOs by seeing more patients, ponder is something they cannot do. And in places like ER, the very nature of what they do forces the physicians to work quickly. One ER physician is quoted as saying that he feels like a circus juggler, spinning plates on a stick; slowing down will cause everything to crash. Similarly, a primary care physician is quoted as saying that looking for the out of the ordinary gets very hard because she feels like someone looking for a face in a passing train; if the train goes faster and faster or if you get distracted, you can easily miss that face. Dr. Kroopman states that on the average, a radiologist views 150 CAT scans over a weekend and a CAT scan has dozens of images; new technologies such as MRI produce hundreds of images. Scanning them visually looking for errors takes time and time is always pressing (on the other hand, a radiologist who looks at an image for more than 38 seconds, risks seeing things that aren’t there).
Physicians also have to walk a balancing act between raising unnecessary fears and ignoring real problems. Learning how to communicate becomes a key factor. Dr. Kroopman says that there is a myth that a brilliant doctor is a poor communicator and a good communicator is a poor doctor. Both are essential, he says. A good doctor is one who communicates well, listens and speaks. The kinds of questions (s)he asks can result in a diagnosis arrived at through a stream of cognitive errors. Most of us are afraid and anxious when we visit a doctor, we also don’t want to appear stupid, as somebody wasting the doctor’s time. If we perceive the doctor is rushed or don’t get asked the right set of questions, we may not provide the information necessary to arrive at the right diagnosis. A study found that on average, a doctor interrupts a patient 18 seconds after the patient first starts telling their story.
Dr. Kroopman also says that much of what doctors practice is a result of where and under whom they studied. Shanthala tells me of procedures that were insisted on in her MD program that the hospital where she works don’t insist and instead do it slightly differently. “Playing God” is a familiar term used to describe doctors. Part of that allure is the mask of certainty that most doctors exude. Dr. Kroopman says that the orthodox and conservative medical establishment fosters such attitudes.
What Can We Do
Reading books like this can leave us wondering if there’s anything we can do. Fortunately, Dr. Kroopman offers lots of suggestions, questions that we can ask to jar the doctor out of their heuristics. For example, we can ask what organs are around where we’re having the problem forcing the doctor to consider other possibilities than gall stones. Or we could ask the doctor to compare the lingering pain post-surgery to having a tooth pulled to get more specific answers. He even helpfully summarizes all these questions in a single epilogue.
Dr. Kroopman addresses these and much more in a book filled with real life anecdotes, many from his own life, both as a doctor and as patient; most of the cases are real cliff hangers. He rarely casts a jaundiced eye on either the doctor, the system or the patient, though he does sound skeptical about the current health care system with insurance companies and big pharma calling the shots. Overall, a very knowledgable and pleasurable read. Highly recommended.
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