Every Patient Tells A Story Part 9

CHAPTER NINE.

Sick Thinking.

David Powell sat quietly in the tiny emergency room cubicle. His muscular arms and chest were barely covered by the thin cotton hospital gown. He looked far too robust to be in the hospital, and yet this was his fourth emergency room visit in two months. "I'm losing my strength," he explained quietly to Dr. Christine Twining, a young physician-in-training. "Doctors keep telling me I'm not having a heart attack. Okay, that's good, I'm glad it's not my heart. But can't anyone tell me what is is wrong?" wrong?"

It had started a couple of months earlier, when twenty-seven-year-old David noticed that his hands and fingers felt numb. Then he started having chest pains-a strange tightness or heaviness that made it hard for him to breathe. That's what sent David to his local emergency room the first couple of times. His mother had recently died of a heart attack and he was afraid he was having one too. Once the ER doctors heard his story, they too thought it was his heart. But at each visit the EKG was normal, the blood tests showed he wasn't having a heart attack, and the stress test suggested he wasn't likely to have one anytime soon. That was rea.s.suring, but it wasn't an answer.

As autumn turned to winter, David began to have a hard time keeping up at work-quite literally. He was a garbage collector and noticed that the short sprints from house to truck, which had been part of his daily routine, now left him panting. And the cans he emptied were somehow heavier. His muscles hurt constantly; he had frequent cramps. By the end of the route, his arms and legs shook with fatigue.

"The guys would ask me what's wrong, 'cause I'm strong, a weightlifter, and I was too ashamed to tell them I was getting weak," David told the young doctor. "I'd just tell them I'd worked out at the gym real hard the day before."

The truth was, he hadn't been able to work out for weeks. He simply didn't have the strength. There were other symptoms too: he was losing weight-twenty pounds in two months. And he was tired. After work, he'd nap, get up for supper, then go back to bed. He also had terrible constipation.

Then, just before Christmas, he was shopping with his wife and kept b.u.mping into the shoppers crowding the mall. "I couldn't make myself go straight," he said. And his chest felt squeezed, as if he were wearing some kind of girdle around his rib cage. When he began to stagger that evening his wife insisted he go to the emergency room once more. During this visit, his third, there was another normal EKG, another normal set of blood tests, another doctor rea.s.suring him and his wife that he wasn't having a heart attack.

A week later, he almost fell off the back of his truck. "My fingers were so weak," he said, "I couldn't hold on tight. Just one b.u.mp and I would have been on the ground."

That's what brought David to the ER this time. As he told his story-his voice soft and level-he studied his hands, describing their disobedience: these days he had to use both hands to hold up his coffee cup; his handwriting had become a childish scrawl-barely legible even to himself; his fingers could no longer distinguish the coa.r.s.e cotton of his work clothes from the smooth silkiness of his Sunday tie.

When David returned to the Emergency Department this time, the ER doctor had again gone for the EKG and the blood tests to look for evidence of a heart attack. It's practically a reflex when someone presents with a chief complaint of chest pain. Still, as he reviewed the young man's chart the doctor knew that these were unlikely to provide any insight into what brought this guy back time after time. Emergency room physicians are trained to diagnose and treat life-threatening illnesses-true medical emergencies. For the majority of patients who come to an emergency room and do not have these immediate emergencies, ER physicians make another very important decision about their care: does the patient need to be admitted to the hospital or is this something that can be followed up as an outpatient? While this guy had one of the key symptoms we are all taught to attend to-chest pain-the ER physician thought that it was unlikely the usual chest pain workup was going to provide this man with the diagnosis he sought. So he asked Christine Twining, one of the internal medicine residents-in-training, to see him and admit him to the hospital so that someone could figure out what was going on. While it probably wasn't an emergency, it seemed to him that this young guy really was sick.

Twining listened carefully to David's story. He was so young and healthy-looking. What could be wrong with him? He was only twenty-seven years old; he didn't smoke or drink. He lived with his wife and their six-year-old daughter. Although his mother had died at fifty-five of a heart attack, and two cousins had sickle cell anemia, the rest of his family was fine.

Physically he was ma.s.sive. He was just over six feet and weighed 240 pounds-lifting weights had chiseled off most of the fat, so what was left was muscle. On examination there was no evidence of atrophy in the well-defined muscles, and while he easily pa.s.sed the standard doctor's-office tests of strength, Twining thought that was because those tests were not designed for someone with greater-than-average strength, like this young man.

He'd complained of numbness in his hands and feet. When Twining examined them they certainly looked normal, but when she jabbed them with the pointed instrument she used to test sensation, he couldn't feel it. And when she tapped his joints with her small rubber hammer, the usual spontaneous jerk was completely absent. He had no reflexes. When she asked him to close his eyes and tell her whether she had moved his big toe up or down, testing one of our most primitive senses, he couldn't even tell her that.

Then the doctor noticed a result from a blood test done on one of the patient's previous visits to the ER: he had a low red blood cell count. Anemia is unusual in an otherwise healthy young man. He had two very different symptoms-anemia and this odd weakness and loss of sensation. Were they linked? She couldn't know based on the data she had so far.

She focused first on his loss of strength and the loss of sensation in his arms and legs: having both problems made it clear it was his nerves-and not his muscles-that were the problem. There were dozens of possible causes for this type of neuropathy: diabetes, alcohol abuse, syphilis, HIV, thyroid disease, cancer. But none really fit this patient.

Given his occupation, the doctor considered an unusual cause of this type of nerve damage: toxins. Could he have been exposed to some dangerous substance discarded thoughtlessly or illegally in the regular garbage? a.r.s.enic could cause this kind of nerve damage; lead and mercury could as well. Moreover, these toxins could account for the anemia as well as the neuropathy, if they were in fact linked.

And what about the anemia? Had his low red blood count predated this new illness? Sickle cell anemia ran in his family, and although he had no symptoms of this painful disorder, could these chest pains be from this trait? He complained of abdominal pain: could he be losing blood in his stomach or intestines? It was possible, though his stools had not shown evidence of blood when tested.

The report from the lab described a few abnormal white cells in his blood: the cells contained irregularly shaped nuclei. This suggested he was anemic because of a nutritional deficiency. A diet poor in folate or vitamin B12 could cause anemia as well as this type of abnormal white cell. Moreover, vitamin B could cause anemia as well as this type of abnormal white cell. Moreover, vitamin B12 deficiency could cause neurological symptoms too. It's easy to get adequate amounts of vitamin B deficiency could cause neurological symptoms too. It's easy to get adequate amounts of vitamin B12 in a normal diet, and it seemed very unlikely that this well-nourished young man could have such a deficiency. But the doctor needed to be sure because the body can't make its own vitamin B in a normal diet, and it seemed very unlikely that this well-nourished young man could have such a deficiency. But the doctor needed to be sure because the body can't make its own vitamin B12 and a true deficiency can cause permanent disability-even death. And treatment is easy and safe: replacing the missing vitamins usually reverses all the symptoms. and a true deficiency can cause permanent disability-even death. And treatment is easy and safe: replacing the missing vitamins usually reverses all the symptoms.

Twining sent off blood samples to look for the origin of the anemia and for evidence of a recent exposure to mercury and a.r.s.enic. Other causes of this neuropathy, she thought, were much less likely, and she could test for them later, if necessary.

The results of the anemia workup came back first. David had no evidence of sickle cell disease or any other congenital blood disorders. He had normal levels of iron and folate. But his level of vitamin B12 was dangerously low: a tenth of the normal level. The doctor was sure this was the cause of David's weakness, numbness, constipation, and anemia. It could even account for his chest pain and shortness of breath. was dangerously low: a tenth of the normal level. The doctor was sure this was the cause of David's weakness, numbness, constipation, and anemia. It could even account for his chest pain and shortness of breath.

The cause of David's anemia was proved by yet another blood test. He had an autoimmune disease that goes by one of those great nineteenth-century names: pernicious anemia. In this disease, the body's own immune system mistakenly destroys the protein responsible for absorbing the vitamin from digested food and getting it into the blood. The immune system makes antibodies for this protein, just as if it were an invading virus or bacteria. David was started immediately on vitamin B12 injections-he would have to take B injections-he would have to take B12 supplements the rest of his life. The results were dramatic and almost immediate. supplements the rest of his life. The results were dramatic and almost immediate.

"Every day I can feel myself growing stronger," David told me when I called him not long after his diagnosis. One week after his first injection he was able to go back to work. "I can finally run again. I can pick up my daughter again. I can tell I'm going to get it all back."

When Thinking Goes Awry David's story is an example of a diagnostic error. Researchers define diagnostic error as a diagnosis that is wrong, missed, or delayed. And although Powell didn't suffer any permanent harm and has been restored to full health, it took four visits to the emergency room to get there.

David was lucky. Many studies show that diagnostic errors often exact a tragic toll. Diagnostic errors are the second leading cause for malpractice suits against hospitals. And a recent study of autopsy findings identified diagnostic discrepancies-a difference between the diagnosis given in life and that discovered after death-in fully 20 percent of cases. The authors of that study estimate that in almost half of these cases knowledge of the correct diagnosis would have changed the treatment plan. Extrapolated to the millions of people in the United States alone who receive medical care every year, that 10 percent of diagnostic errors means a vast toll of avoidable suffering and death.

And patients are worried. One survey showed that over one third of patients surveyed after visiting an emergency room had concerns about medical errors and by far the greatest concern was the possibility that they had been misdiagnosed. They are right to worry. A recent review of the data reported that primary care physicians-those in family practice and internal medicine-had a diagnostic error rate that ranged from 2 to 10 percent. Up to one in ten patients seen was incorrectly diagnosed.

Of course that number only looks at single visits, and anyone who has been to the doctor for a complicated problem knows that it is often figured out over the course of several visits. Emergency room doctors have a somewhat higher rate of diagnostic errors, specialists a somewhat lower rate. This doesn't mean that specialists are better doctors or emergency room physicians are worse. The uncertainty surrounding a diagnosis and thus the likelihood of error is greatest when a patient first presents with a problem-in an emergency room or a primary care office. By the time patients get to specialists much of the uncertainty about their diagnosis has been resolved.

There are many ways of getting a diagnosis wrong. In earlier chapters I looked at how each element of the medical data gathering can break down and lead to diagnostic mistakes-taking an inadequate history or performing an ineffective exam, or not examining the patient at all. A misreading or misinterpretation of a test can also derail the diagnostic process. But perhaps the most common type of diagnostic error-and the one that I will focus on in this chapter-is the one that takes place in the doctor's head: the cognitive error, what I call in this chapter sick thinking. (Anyone interested in learning even more about this important issue should check out Jerome Groopman's outstanding book on the topic, How Doctors Think How Doctors Think.) So how often is an error due to sick thinking? Mark Graber, a physician and researcher at the VA Hospital on New York's Long Island, wanted to answer that question. He collected one hundred cases of medical error from five hospitals over the course of five years. For each case, records were reviewed and, when possible, the doctors involved were interviewed within one month of the discovery of the error. These were serious errors. In 90 percent of the cases patients were harmed by the error; thirty-three patients died.

Graber divided the missed or delayed diagnoses into three categories. (The three categories overlapped somewhat; not surprisingly, most diagnostic errors were due to multiple factors.) "No-fault errors" are mistakes that happen because of factors beyond the control of the doctor making the diagnosis. When a disease presents in an unusual and uncharacteristic fas.h.i.+on-as when an elderly person with appendicitis has a fever but no abdominal pain-or when a patient provides incorrect information-as a patient with Munchausen syndrome might do-a diagnosis can be unavoidably missed or delayed. This was by far the smallest category of diagnostic error, present in only seven of the one hundred cases.

Graber found that our complex and often poorly coordinated medical system also contributes to diagnostic error. If a test result was not reported in a timely manner or if there were equipment failures or problems, he a.s.signed the resulting diagnostic mistakes to the category of "system-related errors." For example, a urinary tract infection might be missed because a urine sample was left too long before being cultured. Or a pneumonia might be missed because an overburdened radiology department hadn't read a critical X-ray correctly. These were relatively common; more than two thirds of the errors Graber studied involved some component of system failure.

The issues that Graber was most interested in were what he called "cognitive errors," by which he meant all errors due to the doctor herself. In his study, Graber attributed more than a quarter of all mistakes made, twenty-eight out of one hundred, to those made due to cognitive errors alone. Half of all the errors made were due to a combination of bad systems and sick thinking.

Graber broke his category of cognitive error down further. Which aspect of cognition was at fault? Was it lack of physician knowledge? Not most of the time. Faulty knowledge was the key factor in only a few of the missed diagnoses, each of which involved a rare condition. Faulty data gathering-an inadequate history, missed findings on the physical exam, or misinterpreted test results-was a more common problem, playing a role in 14 percent of the diagnostic errors. Faulty synthesis-difficulty putting the collected data and knowledge all together-by comparison, played a role in well over half of the incorrect or delayed diagnoses.

In David Powell's case, both the system and the doctors played a role. Early on in his illness David went to two different emergency rooms. Getting records from one ER to another can be a time-consuming affair. Often emergency physicians don't even try to get them because the chances of obtaining them in time to help the patient are so small. So because David went to a different emergency room, his second visit was a virtual rerun of the first visit. And although the patient told the doctor who saw him at his second ER visit that he'd already been "ruled out" for a heart attack or myocardial infarction (MI), without the records to confirm it, the ER doctor repeated the studies rather than risk missing this important diagnosis.

Because the records were not available, David's diagnosis was delayed. Graber would define this as a system-related error. Certainly, in an ideal world, a patient's records should be readily available.

But the emergency room doctors were guilty of thinking errors as well. Each found that the patient was not having a heart attack but none, save the last, carried that train of thought to its next logical destination. None of them asked that most fundamental question in diagnosis: what else could this be? what else could this be? And because they didn't, the diagnosis was missed. And because they didn't, the diagnosis was missed.

They might have missed the diagnosis even had they asked such a question. The differential diagnosis for chest pain is long, and while this is a well-described symptom of pernicious anemia, the disease itself is relatively unusual. But they didn't even try.

In medicine it seems that almost nothing that comes after the words "chest pain" is even heard. And if you are an adult male with chest pain, the odds are almost overwhelming that you are going to end up with a ticket on what I have heard called "the MI express." Far too often those words trigger the cascade of EKGs, blood tests, and even exercise stress tests in search of a heart attack-despite the presence of other signs and symptoms or workups that might suggest a different diagnosis.

Each of these doctors exhibited "premature closure"-one of the most common types of diagnostic cognitive errors. Premature closure is when a doctor latches on to a diagnosis and "closes off" thinking about possible alternative diagnoses before before gathering all the data that would justify going down a particular diagnostic path. In David's case, the doctors' thinking was skewed by two factors: the fact that cardiac problems are so common in the ER, and the potentially dire consequences of a heart attack (which lends urgency and pressure to the task of diagnosis). The doctors heard David describe the cla.s.sic symptom of a myocardial infarction-squeezing or pressurelike pain in the chest a.s.sociated with shortness of breath-and began ordering tests and exams aimed at clarifying the suspected cardiac situation. In premature closure, "Thinking stops when a diagnosis is made." The symptoms of weakness and numbness were noted in the chart in each of the visits but weren't considered on their own even though they are not part of the typical chest pain presentation. When the "MI express" pulls out of the station, far too often everything that doesn't fit-like David's complaint about his loss of strength-is left behind. gathering all the data that would justify going down a particular diagnostic path. In David's case, the doctors' thinking was skewed by two factors: the fact that cardiac problems are so common in the ER, and the potentially dire consequences of a heart attack (which lends urgency and pressure to the task of diagnosis). The doctors heard David describe the cla.s.sic symptom of a myocardial infarction-squeezing or pressurelike pain in the chest a.s.sociated with shortness of breath-and began ordering tests and exams aimed at clarifying the suspected cardiac situation. In premature closure, "Thinking stops when a diagnosis is made." The symptoms of weakness and numbness were noted in the chart in each of the visits but weren't considered on their own even though they are not part of the typical chest pain presentation. When the "MI express" pulls out of the station, far too often everything that doesn't fit-like David's complaint about his loss of strength-is left behind.

Pat Croskerry is an emergency room physician and a doctor who has written extensively about diagnostic thinking. The brain, says Croskerry, uses two basic strategies in working to figure things out. One is what Croskerry calls an intuitive approach. This "nona.n.a.lytic" approach works by pattern recognition. He describes it as a "process of matching [a] new situation to one of many exemplars in your memory which are retrievable rapidly and effortlessly. As a consequence, it may require no more mental effort for a clinician to recognize that the current patient is having a heart attack than it is for a child to recognize that a four-legged beast is a dog."

This is the instant recognition of the true expert described by Malcolm Gladwell in his book Blink Blink-fast, a.s.sociative, inductive. It represents "the power of thin slicing ... making sense of situations based on the thinnest slice of experience." Intuition leads to a diagnostic mode that is dominated by heuristics-mental shortcuts, maxims, and rules of thumb. This is the diagnostic mode used by the emergency room doctors during David Powell's first few visits to the emergency room with his chest pain and strange weakness.

Croskerry contrasts this almost instantaneous intuitive diagnostic thinking with a slower, more deductive approach to diagnostic thought. As described by Croskerry, this a.n.a.lytical approach is linear. It is a process that follows rules and uses logic to think a problem out. It's the Sherlock Holmes model of diagnostic thought.

Croskerry believes that the best diagnostic thought incorporates both modes, with the intuitive mode allowing experienced physicians to recognize the pattern of an illness-the illness script-and the a.n.a.lytic mode addressing the essential question in diagnosis-what else could this be?-and providing the tools and structures that lead to other possible answers.

For Christine Twining, the doctor who finally diagnosed David Powell with pernicious anemia, there was no Blink Blink-like moment of pattern recognition and epiphany when she first heard him describe his symptoms. One thing seemed clear: he wasn't having a heart attack. She felt the patient's fear and frustration. "He was afraid I was going to send him home with rea.s.surances that it wasn't his heart and without figuring out what it was. But I couldn't send him home; I didn't have a clue what he had."

Because there was no instantaneous sense of recognition triggered by Powell's odd combination of chest pain, weakness, and anemia, Twining was forced to approach the problem systematically, considering the possible diagnoses for each of his very different symptoms and pursuing a slower, more rational approach to the patient that ultimately brought her the answer.

Both types of thinking are essential in medicine. Which to use will depend on the perceived degree of uncertainty surrounding a set of circ.u.mstances. The more certainty there is in any given set, the more closely it aligns with some recognized or remembered disease state, the more likely you are to use the intuitive response. The cognitive continuum of decision making, says Croskerry, runs from informal/intuitive at one end to calculated/a.n.a.lytical at the other, and the nature of the tasks runs from quite simple to complex. "The trick lies in matching the appropriate cognitive activity to the particular task."

Much of the research that has been done on cognitive errors focuses on the misinterpretation of medical information. In David's case, the doctors who missed his diagnosis of pernicious anemia focused on only a couple of his symptoms, ignoring the history of numbness and weakness, the abnormalities in his physical exam, even the anemia, in their concern not to miss a heart attack. But errors can also arise from interpretations of data we're not even aware we are making, thanks to a.s.sumptions and biases that we bring with us from our lives outside the hospital.

Physician Bias, Fair and Otherwise "Doc, my knee, it's doing this thing again." Vera Freeman pointed to her red and swollen knee as I entered the small, poorly lit hospital room. She was an attractive young woman, with hair stylishly braided and ornamented with bright beads. "Last night it was just fine," she reported. "Now just look at it."

Two weeks earlier, she awakened to find her ankle-not her knee-swollen and painful. She didn't remember injuring it. "It just blew up," she said, and when she took it easy for a couple of days, it got better. "But just as soon as it was okay, my wrist swelled up. It was big, and it really hurt. I was getting worried, but it got better too." The next week, though, her knee began to swell, and she decided to come to the hospital. "It was so weird. It was like I had this swelling that just didn't know where to light." She looked at me carefully, to see if I was following her story.

She stayed in the hospital for a couple of days, received some intravenous antibiotics, and was sent home with antibiotics to finish by mouth. She took the pills for a couple of days, but once she felt better, she neglected to take the rest. Now the pain and swelling had wandered back, and she wanted to know why.

Freeman was frank about her history. She had HIV, which had been diagnosed three years before. Otherwise, she thought she was pretty healthy. She did not smoke cigarettes or drink, though she did admit to smoking crack cocaine "occasionally." She had no children, lived in an apartment with her longtime boyfriend. She had, at times, worked as a prost.i.tute to help her buy crack.

On exam, her dark brown skin felt warm. Moving the joint elicited a sharp cry of pain. As I gently explored the swollen knee, I could feel fluid moving around, like a warm, firm water balloon. The kneecap was separated from the joint it normally covers; I could press it down almost an inch before I felt contact. As I examined her, I a.s.sembled a differential diagnosis in my head. A hot, swollen joint is routine in medicine, usually caused by trauma, by gout, by infection. But this "wandering" pain was far from routine. In the textbooks it's known as a "migratory polyarticular arthritis"-that is, an arthritis that moves from joint to joint-and it is an extraordinary manifestation of just a few pretty ordinary diseases.

It is seen most commonly with gonorrhea (although it is unusual even in this disease), where it is often accompanied by fever and a rash. Lyme disease can also manifest this way, as can viruses like hepat.i.tis and even HIV. But none of those seemed to fit. There were other, less likely possibilities. Rheumatoid arthritis can come on like this, as can lupus.

Justin Thompson, the intern working with me that month, had admitted Freeman for her earlier hospitalization. When I asked him about her, he wearily flipped through a stack of index cards that he pulled from his pockets. "Right. We tapped her knee and cultured her up," he said, meaning that they'd drawn fluid from her knee, which should offer some clues, and had sent off some of the fluid, as well as her blood and urine, to check for evidence of infection. "I thought it was gonorrhea," the intern stated flatly. "It's not the way you usually see it, but gonorrhea can definitely cause this."

The art of diagnosis can look a lot like profiling. Doctors constantly ask: Is a particular condition more common in men or women? Whites or blacks? The young or the old? In this way a doctor narrows the possible causes of a given illness in a given patient. Gonorrhea, then, was the most likely diagnosis for this young, s.e.xually active, onetime prost.i.tute. And while none of the tests had confirmed it, none ruled it out either.

But here she was again, knee gigantically swollen-again. This was not part of the disease profile, yet the intern working with me was undeterred. So much so that he had already ordered antibiotics to treat her presumed infection. Because she did not finish her course of antibiotics, the disease had been only partly treated; therefore, all she needed was more antibiotics. "Or maybe her boyfriend was the source," he said, "and she's been reexposed since getting treated. Or maybe she's back on the street."

These were all reasonable thoughts, but it was clear to me that we needed more evidence to make that diagnosis a second time. I thought we should hold the antibiotics until after we tapped the knee again and repeated her cultures.

I was also interested in the results of the blood tests from Freeman's earlier hospitalization. I found a computer and tracked down her test results. Lyme was negative; hepat.i.tis, negative; gonorrhea and syphilis, negative. In fact, there was only one set of positive results: the tests for recent strep infection along with several other blood tests consistent with a diagnosis of rheumatic fever. The problem is that rheumatic fever rarely occurs in these days of antibiotics, and when it does it is seen almost exclusively in children. It is practically unheard of for an adult to develop it. Even now that she met some of the criteria for the disease, such a diagnosis was hard to make. She simply didn't fit the profile.

We went back to the patient. Had she had a sore throat recently? Yes. She'd had a sore throat a few weeks before, but she thought it could have been because of the crack. That convinced me. It now seemed clear that, as unlikely as it might have seemed initially, this young woman had rheumatic fever.

When we went back to the patient, she was dressed and ready to leave. Her knee, which had been red and hot and excruciatingly painful only twenty-four hours earlier, had improved significantly with no intervention. We scheduled her to see her doctor the following week. As she stood with her bag in hand, I tried to explain rheumatic fever and what it might mean to her, but she wasn't listening.

"I'm better," she announced, "so I'm gone." I gave her her prescriptions and shook her hand, then watched as she limped down the hall, waved gaily from the door, and disappeared.

Recently I caught up with her doctor, who told me that Vera had gotten an echo to look for any signs of damage to her heart or their precious valves that direct the flow of blood through the organ. Everything was completely normal. And it made sense. Cardiac injury is very common in the children who get rheumatic fever; in adults the disease tends to "bite the joints and lick the heart," causing joint pain but not the more significant cardiac lesions.

What has always stuck in my mind is the intern's insistence on the diagnosis of gonorrhea even in the face of failed tests for that condition. Was he just being prejudiced against a minority woman with a history of behaviors not sanctioned by the larger society? Possibly, but I think the story is more complicated than that.

At first glance, patients might think that the ideal in diagnosis would be for a doctor to treat (and view) all of their patients identically-to be color, age, gender, and socioeconomically blind. We don't want our looks to influence our doctor's objective a.s.sessment of our health problems. And yet they must. Illnesses and diseases do not abide by our const.i.tutionally required equal protection. Diseases do do discriminate on the basis of race, gender, age, and even socioeconomic status. discriminate on the basis of race, gender, age, and even socioeconomic status.

To take a obvious example: the vast majority of breast cancer patients are women, so it is not wrong for a doctor to automatically drop that diagnosis down in her priority list when confronted with a male patient with a lump on his chest. A less obvious example is prostate cancer: black men are significantly more likely to get this type of cancer than men of other races-four times more likely, in fact, than Korean men, nearly twice as likely as men of European descent. So if a black man comes to a doctor complaining of urinary symptoms, a good doctor will automatically raise her level of suspicion for prostate cancer based solely on the color of the patient's skin. In fact, it would be irresponsible of the doctor not not to take race into account when considering this diagnosis. to take race into account when considering this diagnosis.

Viewed in this light, the bias of the intern clinging to his suspicion of gonorrhea in a woman with a history of drug use and prost.i.tution is not so egregious. Using drugs and having multiple s.e.x partners, after all, are legitimately a.s.sociated with an increased risk for s.e.xually transmitted infections. What would be egregious is if the intern (or anybody else) settled on a diagnosis of gonorrhea based only only on the color of the woman's skin, her clothing, or some other aspect of her appearance or behavior, all of which have nothing to do with one's risk of gonorrhea. on the color of the woman's skin, her clothing, or some other aspect of her appearance or behavior, all of which have nothing to do with one's risk of gonorrhea.

In other words, patients want doctors to be legitimately biased legitimately biased in their thinking and decision-making processes when struggling to find a diagnosis. Doctors should take into account any known a.s.sociations that might help pin down the cause of an illness. But diagnoses can be missed when doctors apply false generalizations or close off diagnostic possibilities just because they are less likely in a certain group or population (e.g., "This can't be HIV because the patient is elderly"). Research has shown that medical decision making is shaped by many of the same influences that distort other aspects of human interaction. Indeed, says one group of researchers, "despite their 'objective' medical training, physicians remain human actors, socially conditioned to engage in stereotyping, whether consciously or not." In that respect, medical decision making can be a function of who the patient is as much as what the patient has. in their thinking and decision-making processes when struggling to find a diagnosis. Doctors should take into account any known a.s.sociations that might help pin down the cause of an illness. But diagnoses can be missed when doctors apply false generalizations or close off diagnostic possibilities just because they are less likely in a certain group or population (e.g., "This can't be HIV because the patient is elderly"). Research has shown that medical decision making is shaped by many of the same influences that distort other aspects of human interaction. Indeed, says one group of researchers, "despite their 'objective' medical training, physicians remain human actors, socially conditioned to engage in stereotyping, whether consciously or not." In that respect, medical decision making can be a function of who the patient is as much as what the patient has.

Studies in social science have doc.u.mented many nonmedical factors that influence medical decisions, including characteristics of the patient such as age, gender, socioeconomic status, race, or ethnicity. These can be important considerations in prioritizing possible diagnoses. But characteristics that have no obvious medical meaning-such as the presence or kind of health insurance, a.s.sertive personality type, or even physical attractiveness-have also been shown to play a role in how doctors make decisions about medical diagnosis and care. And even those factors that can affect the probability of disease in some cases, factors such as age and s.e.x, are extraneous in many others.

One of the many careful experiments designed to tease out such influences ill.u.s.trates this point. A set of videotaped doctor-patient encounters was created using professional actors. Scripts were created for male "patients" and female "patients" who complained of a set of cardiac symptoms. The scripts and all presenting details were identical in every respect aside from trivial changes in personal p.r.o.nouns and the like. Two hundred fifty-six doctors practicing in both the United States and the United Kingdom were recruited for the study. They viewed either one or the other video scenario and were then asked a series of questions about what disorder they suspected, what treatments or recommendations they would suggest, and so on. Coronary heart disease (CHD) was chosen because it is the leading killer of both men and women, and although age-specific mortality rates are higher for men than women, twice as many women as men aged forty-five to sixty-four have undetected or "silent" CHD, which suggests that the true incidence between men and woman may be similar. This is a case, in other words, in which doctors should not not apply a bias in their decision-making processes-here a gender bias. apply a bias in their decision-making processes-here a gender bias.

The study results, however, clearly demonstrated just such a bias. Gender was found to have significant influence on all aspects of doctors' diagnostic strategies; in each case women received less attention than men presenting with CHD symptoms. Doctors would ask men more questions than women (on average 7 and 5.7 questions, respectively) and perform more extensive examinations for men than women (5.1 compared to 4.3 parts of the body or body systems would be examined, respectively). CHD was mentioned as a possible diagnosis for more men than women (95 and 88 percent, respectively), and doctors had significantly higher certainty of CHD for male than female patients, 57 and 47 percent, respectively, on a scale of 0 (total uncertainty) to 100 percent (total certainty).

The study authors concluded: "Our findings indicate that women presenting with CHD symptoms are disadvantaged in primary care. Doctors provide a less thorough diagnostic search procedure than for men presenting with identical symptoms, and fewer women are given prescriptions appropriate for treating CHD."

The impact of conscious or unconscious bias on the diagnostic thinking processes of doctors adds to the complexities of the entire doctor-patient experience. The best doctors acknowledge their vulnerabilities and try hard to retrain themselves or monitor themselves and their thinking processes as they move through any given diagnostic challenge.

The last type of cognitive error I want to talk about is what's often called in the cognitive literature diagnostic momentum. This is a kind of medical groupthink in which once a diagnostic label is attached to a patient, it tends to become "stickier and stickier." Doctors are taught in medical school that they should not simply accept a diagnosis given to a patient but should reevaluate the data for themselves before accepting or sometimes rejecting this diagnosis. That we should, as former president Ronald Reagan often exhorted (in a very different setting), "Trust but verify." Rather than accept a previous diagnosis, doctors are supposed to start fresh by thinking things through for themselves. This, of course, is much easier said than done.

If a doctor is tired or in a hurry, she is far less likely to take the time to review all the test results and other evidence that went into the diagnosis. And even if she does expend the effort to do that, it's difficult to not fall into the same well-defined disease pattern-potentially mistaken or not-that those who have seen the patient already have defined. But that kind of extra effort can sometimes pay off dramatically.

The Doctor of Last Resort Graciela Moity spoke in a slow, husky vibrato. She sounded weary, discouraged. "I can remember clear as day when it all began," she said. "It was just over a year ago. I woke up and felt like my legs were on fire."

She was talking to Dr. David Podell-the most recent of a train of doctors who had evaluated the woman since that day she awoke in such pain. The three previous doctors couldn't figure out what was going on. Their best guess was scleroderma, a disease caused by the overproduction of one of the connective tissues, collagen. The patient's symptoms weren't a great fit, but sometimes the disease could manifest itself in unusual ways. She was referred to Podell for confirmation of the diagnosis and treatment of this unusual autoimmune disorder.

With years of experience under his belt, Podell knew that when a patient has already been to a slew of specialists before arriving at your door, you need to approach the case with a different mind-set-with different a.s.sumptions. You know, for example, that whatever this patient has, it isn't going to be obvious. Maybe it's an unusual disease, known best by specialists-like scleroderma-or perhaps it's an unusual presentation of a more common illness. In any case, it won't be routine. In such situations, he knew, you had to start from scratch even if the patient comes to you with a diagnosis already made. He asked the woman to continue with her story, apologizing because he knew she had told and retold it so many times already in the past year.

She said that until that morning a year ago she had always been healthy. But the burning pain in her legs had been so intense that now she could hardly walk. And she had felt weak-especially in her left leg. She went to her regular doctor, but he didn't know what to make of her symptoms and sent her to a neurologist. He examined her, sent off a dozen blood tests, and got a CT scan of her head and spine before sending her back to her internists, still undiagnosed.

Then she developed a cough. It was usually a dry, irritating cough, but occasionally she coughed up blood. Recently she felt out of breath with even slight exertion. This morning, she told Podell, she had to stop and rest during the short walk from the parking lot to his office. Her internist sent her to a pulmonologist because her lungs seemed clearly involved. He got a chest X-ray, then a chest CT, more blood tests, even a biopsy. The chest X-ray proved that her lungs were involved. In the normally black areas of the image over the air-filled lung tissue, there were faint patches of white. The biopsy showed inflammation but nothing more specific. He wasn't sure what this was. He tried her on a variety of antibiotics. Finally he sent her back to her internist, suggesting the possibility of scleroderma.

Eventually her internist sent her to Podell, who is a rheumatologist-a specialist in diseases of connective tissues. Because connective tissues are found throughout the body, complex, multisystem illnesses are the rheumatologists' bread and b.u.t.ter.

The patient was a slender woman with a ma.s.s of straight dark hair streaked with gray. Her skin was clear, but her eyes were puffy with fatigue, and she looked older than her fifty-three years. Examining her, Podell found few obvious signs of disease. Despite the cough and breathing problems, her lungs sounded clear. She had some mild weakness in her left hip, but other than that, her joints, skin, and muscles were all normal.

Podell could see why the previous doctors were puzzled. Her symptoms suggested that her illness involved the nervous system and the pulmonary system, which is an unusual pairing. Although scleroderma can affect both nerve and lung tissue, Moity didn't have the cla.s.sic thickening of the skin that is the hallmark of that disease. Could this be an atypical form of scleroderma? Or was it something else altogether?

Could this be Sjogren's syndrome, a disease in which the immune system mistakenly attacks a patient's fluid-producing glands? Sjogren's can affect the lungs and sometimes spreads to the nervous system. Patients with Sjogren's usually complain of painful eyes or a dry mouth, and this patient had mentioned that her mouth was dry.

Podell ordered blood tests to look for evidence of Sjogren's. He a.s.sured the patient that he would do all he could to figure out what was going on, but that it would take a bit more time. Looking defeated, Graciela Moity made an appointment to return in a couple of weeks and trudged out toward the parking lot.

Podell wanted to examine the patient's extensive medical record, especially the tests and results obtained by the other doctors. He didn't read the records in advance in complicated cases. He felt it was important to take in the information without any preconceived notions about what was going on. But at the end of the day Podell sat down with her thick chart and went through every page. When you are the last in a string of pract.i.tioners, one of your most important jobs is to review each piece of the puzzle with fresh eyes, questioning every a.s.sumption and double-checking the reported results. In complex cases like this, the answer is sometimes already there, just waiting to be noticed.

A long list of blood tests had been done. Several suggested an inflammatory process, but none identified the cause. The patient also had MRIs of her head and spine, as well as a CT scan of the chest. Podell was particularly interested in the chest CT, which showed something he could not have detected in his physical exam: faint, cloudy patches throughout both lungs. He wasn't an expert in interpreting CT scans, so he called in a radiologist to look them over. But the colleague merely confirmed what Podell could already see: cloudy areas showed the presence of fluid in both lungs. Etiology: unknown.

The patient had also had a lung biopsy. The pathology report said there was evidence of inflammation but, like the blood tests, revealed nothing of the cause. But, again, Podell sought an expert opinion-in this case from the pathologist Tom Anderson. Podell and Anderson sat at a double-headed microscope in the pathology lab, scanning slides that held the biopsy samples. The first slide showed evidence of extensive inflammation, Anderson agreed, but nothing more. As he zipped across the second slide, Anderson reported that again he saw lots of inflammation. Suddenly he stopped. He quickly flipped the microscope lens to zoom in tight on one group of cells that formed a cl.u.s.ter, quite different in appearance from the cells around it.

"That looks like a granuloma," he said.

These distinctive cell formations are characterized by groups of giant cells up to a hundred times larger than normal cells. They are seen in the lungs only in a few diseases-most commonly sarcoidosis (known more commonly as sarcoid) and tuberculosis. Podell almost laughed out loud. At last, the needle had fallen from the haystack. He picked up the phone and called the patient.

"I know what's going on," he told her. "I can explain everything."

The culprit, Podell explained, was almost certainly sarcoid, a mysterious chronic disease characterized by inflammation of tissues that often display the unusual granuloma collections of cells. The disease usually affects the lungs, but in one third of cases can attack other parts of the body as well, including (rarely) the nervous system. He told her she would need to be tested for tuberculosis, as that disease can also cause granulomas, but he was confident that's not what she had. She had none of the common symptoms of TB such as night sweats, weight loss, or fever. No, Podell said, this is overwhelmingly likely to be sarcoid.

Podell started the patient on the corticosteroid prednisone, which is a highly effective anti-inflammatory medicine. Almost immediately her breathing became easier and the cough disappeared. Within a few days she was walking up and down stairs, something she hadn't been able to do for more than a year. The damage to the nerves in her legs would take longer to treat and may not be completely reversible, but with the diagnosis now clear and effective treatments known, the prognosis for a full recovery was excellent.

Dr. Podell wasn't born an excellent diagnostician. He didn't always know to check and double-check the work of other doctors earlier in the "train" for any particular patient. He learned this and many other invaluable lessons about diagnosis over the course of a long career. And that, in the end, is why we can be hopeful that doctors and other health care providers can avoid or even eliminate the types of cognitive errors we have encountered in this chapter. Yes, doctors are human beings and, thus, are p.r.o.ne to biases, distortions of perspective, and blind spots. But doctors have the capacity to learn from their mistakes, overcome built-in biases, and guard against the kinds of thinking errors that in other professions might only be an annoyance.

I recall a rather mortifying moment in my own learning curve. I was in my third year of medical school. I was given a very simple task by an experienced doctor: to intubate an unconscious patient. Intubation is to medicine what boiling water is to cooking-one of the most basic techniques you can think of. And yet I blew it. Because both the trachea (the tube for air) and the esophagus (the tube for food) diverge at the back of the throat, it is relatively easy to slide the breathing tube into the esophagus. Doing so, of course, is a potentially deadly mistake. Students are therefore repeatedly taught to listen to the lungs for sounds of air movement after placing the breathing tube. If you've accidentally put the tube into the stomach, the lungs will be silent. When I listened I heard the terrible silence that means you've made this basic error. Under the gaze of my supervising doctor, I removed the tube and tried again, feeling extremely embarra.s.sed in the process. But the doctor was not annoyed or disappointed. And what he said next has always stuck with me.

"There's no shame in intubating the esophagus," he said. "But there is is shame in not checking or catching the error." shame in not checking or catching the error."

His point was that errors themselves are unavoidable. Mistakes will always happen-all types of mistakes, from the technical to the cognitive. But that doesn't mean we throw up our hands in helplessness. The key is designing our systems, our procedures, our protocols, and our own thinking processes to minimize mistakes as much as possible and then to catch catch mistakes when they are made. mistakes when they are made.

Medicine is not the only field in which mistakes can be deadly. The airline industry, to take just one example, has had to put into place many systems for preventing and catching human errors. In the 1930s, following a crash in which a test pilot and crewman were killed due to "pilot error," the air force responded by requiring every pilot and copilot to complete a pre-takeoff checklist before each flight. The rate of accidents plummeted, and eventually this became standard practice for military and commercial pilots. Most airlines also now require pilots and crew to review the flight plan just before takeoff. This is done as a group and anyone in the crew, from pilot to steward, can bring up any problems they see or antic.i.p.ate. Pilot and crew are drilled on safety procedures for a wide variety of problems, often using flight simulators to make the experience as real and useful as possible. These basic steps are part of a broader movement that has dramatically improved air travel safety.

There is a national effort now being made to eliminate many of the errors in medicine, to implement layers of checks and double checks to catch errors before they happen. Many of the strategies developed by the airline industry have been adapted and incorporated into hospitals and operating rooms throughout the United States. For example, there is an effort to require surgeons to complete a pre-surgical checklist with all the members of the surgical team. Before any operation, the team meets and anyone, from the anesthesiologist to the scrub nurse, can bring up any problem they see or antic.i.p.ate. A recent study in the New England Journal of Medicine New England Journal of Medicine showed that the use of a nineteen-item surgical safety checklist decreased mortality by nearly 50 percent and the rate of complications overall by a third. A recent study showed that the use of a checklist before certain procedures in the ICU can also reduce medical errors by 80 percent and save lives. showed that the use of a nineteen-item surgical safety checklist decreased mortality by nearly 50 percent and the rate of complications overall by a third. A recent study showed that the use of a checklist before certain procedures in the ICU can also reduce medical errors by 80 percent and save lives.

Most of this effort has been directed at system errors-when the wrong drug is given or the wrong type of blood transfused. When the wrong leg is amputated. These were the errors identified in a report by the Inst.i.tute of Medicine (IOM), To Err Is Human To Err Is Human, published in 2000. Hospitals have been in the forefront of this movement and there are efforts to punish hospitals that have been slow to address these problems.

Diagnostic error, however, hasn't been part of that effort. In fact, when one researcher searched the text of the IOM report, the term "medication error" came up seventy times but the term "diagnostic error" came up only twice. This was true even though the study that this report was based on found that diagnostic errors accounted for 17 percent of all the errors made.