August 12, 2008
Jerome Groopman’s “How Doctors Think”
Those of you who have followed our Tip of the Week column for over a year and a half now realize we usually do a book review when we return from vacation. This time we’re reviewing Jerome Groopman’s “How Doctors Think”. I was a resident with Jerry at the Mass General and know firsthand his outstanding clinical acumen and great bedside manner. I had not realized what a great writer he is. This is one book that anyone involved in patient care, including patients and their families, should read.
In our discussions on root cause analysis in this column we have often talked about how physicians (and other healthcare workers) make decisions in acute or emergent conditions. We have stressed the work of people like Gary Klein (see our May 29, 2008 Patient Safety Tip of the Week “If You Do RCA’s or Design Healthcare Processes…Read Gary Klein’s Work”) on pattern recognition and recognition-primed decision making. Jerry Groopman does discuss the importance of pattern recognition in physician’s thinking. However, his main focus is not so much on acute situations but rather on the day to day thinking that takes place in interacting with patients. And he points out a whole variety of cognitive traps we all fall into in our thinking in such situations.
Two interesting cognitive error traps are the representativeness error and the attribution error. The former is when one’s thinking is guided by a prototype and you fail to consider conditions that contradict that prototype. This tends to occur when you view a patient as a healthy, fit individual and think he would not be prone to some of the disease states that should be considered in your differential diagnosis. The attribution error is similar but more often feeds on negative cues. For example, the smell of alcohol on the breath of a patient may erroneously lead the physician to think the patient is an alcoholic, pushing the phyician’s diagnostic thinking in the wrong direction. Throughout the book, Jerry reminds us that our own emotions as physicians may bias our thinking and lead us down some error paths. If we really like a patient, we may tend to underdiagnose because we subconsciously want a positive outcome for that patient. This is known as an “affective” error and in such cases we tend to value too highly information that fulfills our wish to see a positive outcome. That, of course, is a form of confirmation bias similar to that we often talk about in our root cause analyses where we seize upon data that seems to confirm our diagnosis and dismiss data that controverts it. Very interestingly, he discusses the potential role that patients and their families may play in helping the physician to avoid attribution errors.
Another phenomenon coloring our thinking is the “availability” phenomenon. This is where the most recent or most memorable cases from the past narrow our thinking about a current patient. We all know how a previous bad experience with use of a medication may influence us not to use it again, even when we know the medical evidence tells us we should use it (one of the reasons so many patients with atrial fibrillation are never placed on coumadin). He illustrates the availability error by providing a patient encounter during an epidemic of pneumonia cases in which an excellent physician did not consider aspirin toxicity because so many other patients had had pneumonia. Again this involves confirmation bias or “cherry picking” only a few key symptoms and rationalizing contradictory data. He also talks about “anchoring” where we latch onto a single possibility and fail to look for alternatives. He recommends that we should always generate at least a short list of alternative possibilities in all decision making to avoid anchoring and confirmation bias.
As an aside, we’ve mentioned anchoring previously and it becomes a more significant problem once a diagnosis or other decision has been declared publicly. Many of you have done an exercise in executive training where a scenario is presented in which you must state a position publicly. You are then given a bit of disconfirming evidence and a chance to change your decision. Almost no one changes their decision! (The scenario is actually a poorly disguised parallel of the Challenger disaster). Another example is when we point out that a geriatric patient is on a drug on Beer’s list. The physician almost never takes that patient off the drug but may in the future be less likely to prescribe that drug in other geriatric patients.
Back to Groopman’s book. One way a patient can combat the anchoring and availability phenomena is to simply ask the physician “What’s the worst thing this could be?”. That often gets the physician to reassess his thinking and consider alternatives. Another question a patient could use is “What body parts are near where I’m having symptoms?”. These simple, harmless questions presented in a nonconfrontational manner can influence a physician to reassess.
Using an example of a patient with a severe nutritional immunodeficiency erroneously felt to be a case of the rare hereditary disosrder severe combined immunodeficiency disorder (SCID). Here he discusses the phenomenon of “diagnosis momentum” in which a certain diagnosis becomes fixed in the physician’s mind despite incomplete evidence. (This is somewhat similar to anchoring). And he talks about “zebra retreat” a term coined by Dr. Pat Croskerry. This refers to our old adage “when you hear hoofbeats, think horses, not zebras”. That, of course, means that common things occur commonly and we should think about atypical presentations of common things rather than rare things. Croskerry notes that we’ve taken that to the extreme and now often fail to consider the unusual conditions. And physicians also tend to use “Ocham’s razor”, where we try to simplify so that all symptoms are explained by one diagnosis. Some of the questions a patient might ask to avoid these sorts of errors in their physician’s thinking are “What else might this be?” or “Is it possible I might have more than one thing going on?”.
Another interesting phenomenon, often seen in radiologist’s reviewing images, is that of “search satisfaction”. There the tendency is to fix on the most flagrant abnormality and fail to search for other abnormalities. You often “see what you want to see”.
In a discussion about approaches to cancer therapy, he talks about the tendency to keep doing the same thing even when it is not working. Often stepping back and saying “What am I missing?” may lead one to move on to another form of treatment that might work. His discussions stress the importance of knowing and understanding what a patient’s goals and hopes are when determining what to do next in complex problems.
We’ve talked previously about the power of story telling. Jerry Groopman masterfully conveys the key points in this book by weaving them into stories, putting a face and personality on the patients and the physicians in each example. To be fair, Jerry attributes most of the key lessons to a host of other fine physicians. He also uses his own interactions with the healthcare system as a patient to illustrate numerous salient points. And he manages to weave into the background issues related to economic and time pressures in medicine, reimbursement and managed care issues, the double edged sword of technological advances, marketing and corporate medicine, and conflicts of interest. This book sends a powerful message to everyone in healthcare. You will see yourself on almost every page, whether you are a physician or patient, healthcare worker or family/friend. Trust me, if you are a physician you will find yourself saying “I remember making that kind of error” many times and hopefully your new insights will lead to more satisfying interactions with your patients. And he ends with an afterword, suggesting patients always help their physicians think openly by asking questions like “What else could this be?”, “Could there be two things going on?”, and “Is there anything in my history or exam or lab tests that is at odds with the working diagnosis?”.
Groopman J. How Doctors Think. Boston: Houghton Mifflin, 2007 (Mariner Books 2008)