The Startling Truth About Doctors and Diagnostic Errors

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http://www.alternet.org/healthwellness/88515/?page=entire & ses=8cc35c8596bfcd095d45cde73dbdb3c1Despite all of the talk about medical errors and patient safety,

almost no one likes to talk about diagnostic errors. Yet doctors

misdiagnose patients more often than we would like to think. Sometimes

they diagnose patients with illnesses they don't have. Other times, the

true condition is missed. All in all, diagnostic errors account for 17

percent of adverse events in hospitals, according to the Harvard Medical Practice Study, a landmark study that looks at medical errors.Traditionally,

these errors have not received much attention from researchers or the

public. This is understandable. Thinking about missed diagnosis and

wrong diagnosis makes everyone -- patients as well as doctors --

queasy. Especially because there is no obvious solution. But this past

weekend the American Medical Informatics Association (AMIA) made a

brave effort to spotlight the problem, holding its first-ever

"Diagnostic Error in Medicine" conference.Hats off to Bob

Wachter, associate chairman of the Department of Medicine at the

University of California, San Francisco, and the keynote speaker at the

conference. Wachter shared some thoughts on diagnostic errors through

his blog Wachter's World.Wachter

begins by pointing out that a misdiagnosis lacks the concentrated shock

value that is needed to grab the public imagination. Diagnostic

mistakes "often have complex causal pathways, take time to play out,

and may not kill for hours [i.e., if a doctor misses myocardial

infarction in a patient], days (missed meningitis) or even years

(missed cancers)." In short, to understand diagnostic errors, you need

to pay attention for a longer period of time -- not something that's

easy to do in today's sound-bite driven culture.Diagnostic

errors just aren't media-friendly. When someone is prescribed the wrong

medication and they die, the sequence of events is usually rapid enough

that the story can be told soon after the tragedy occurs. But the

consequences of a mistaken diagnosis are too diffuse to make a nice,

punchy story. As Wachter puts it: "They don't pack the same visceral

wallop as wrong-site surgery."Finally, Wachter observes, it's

hard to measure diagnostic errors. It's easy to get an audience's

attention by telling it that "the average hospitalized patient

experiences one medication error a day" or that "the average ICU

patient has 1.7 errors per day in their care."But we don't have

equally clean numbers on missed diagnoses. As a result, he points out,

"it's difficult to convince policy makers and hospital executives, who

are now obsessing about lowering the rates of hospital-acquired

infections and falls" to focus on a problem that is much more difficult

to tabulate.This is a recurring problem in programs that strive

to improve the quality of care: We are mesmerized by the idea of

"measuring" everything. Yet, too often, what is most important cannot

be easily measured. Wacther recognizes the urgency of the problem: "As

quality and safety movements gallop along, the need to" address

diagnostic errors" grows more pressing," he writes. "Until we do, we

will face a fundamental problem: A hospital can be seen as a

high-quality organization -- receiving awards for being a stellar

performer and oodles of cash from P4P programs -- if all of its

'pneumonia' patients receive the correct antibiotics, all its 'CHF'

patients are prescribed ACE inhibitors, and all its 'MI' patients get

aspirin and beta blockers."Even if every one of the diagnoses was wrong."Why so many errors?Medicine

is shot through with uncertainty; diseases do not always present

neatly, in textbook fashion, and every human body is unique. These are

just a few reasons why diagnosis is, perhaps, the most difficult part

of medicine.But misdiagnosis almost always can be traced to

cognitive errors in how doctors think. When diagnosis is based on

simple observation in specialties like radiology and pathology, which

rely heavily on visual interpretation, error rates probably range from

2 percent to 5 percent, according to Drs. Eta S. Berner and Mark L.

Graber, writing in the May issue of the American Journal of Medicine.By contrast, in clinical specialties that rely on "data gathering and synthesis" rather than observation, error rates tend to run as high as 15 percent.

After reviewing "an extensive and ever-growing literature" on

misdiagnosis, Berner and Graber conclude that "diagnostic errors exist

at nontrivial and sometimes alarming rates. These studies span every

specialty and virtually every dimension of both inpatient and

outpatient care."As the table below reveals, numerous studies

show that the rate of misdiagnosis is "disappointingly high" both "for

relatively benign conditions" and "for disorders where rapid and

accurate diagnosis is essential, such as myocardial infarction,

pulmonary embolism, and dissecting or ruptured aortic aneurysms."STUDY NAME: Shojania et al (2002)ASSESSED CONDITION: Tuberculosis of the lungs (bacterial infection) FINDINGS:

Reviewing autopsy studies specifically focused on the diagnosis of lung

TB, researchers found that 50 percent of these diagnoses were not

suspected by physicians before the patient died.STUDY: Pidenda et al (2001)CONDITION: Pulmonary embolism ( a blood clot blocks arteries in the lungs) FINDINGS:

This study reviewed diagnosis of fatal dislodged blood clots over a

five-year period at a single institution. Of 67 patients who died of

pulmonary embolism, clinicians didn't suspect the diagnosis in 37 (55

percent) of them.STUDY: Lederle et al (1994), von Kodolitsch et al (2000)CONDITION: Ruptured aortic aneurysm (when a weakened, bulging area in the aorta ruptures)FINDINGS:

These two studies reviewed cases at a single medical center over a

seven-year period. Of 23 cases involving these aneurysms in the

abdomen, diagnosis of rupture was initially missed in 14 (61 percent);

in patients presenting with chest pain, doctors missed the need to

dissect the bulging part of the aorta in 35 percent of cases.STUDY: Edlow (2005)CONDITION: Subarachnoid hemorrhage (bleeding in a particular region of the brain) FINDINGS:

This study, an updated review of published studies on this particular

type of brain bleeding, shows about 30 percent are misdiagnosed on

initial evaluation.STUDY: Burton et al (1998)CONDITION: Cancer detection FINDINGS:

Autopsy study at a single hospital: of the 250 malignant tumors found

at autopsy, 111 were either misdiagnosed or undiagnosed, and in just 57

of the cases, the cause of death was judged to be related to the cancer.STUDY: Beam et al (1996)CONDITION: Breast cancer FINDINGS:

Looked at 50 accredited centers agreed to review mammograms of 79

women, 45 of whom had breast cancer. The centers missed cancer in 21

percent of the patients.STUDY: McGinnis et al (2002)CONDITION: Melanoma (skin cancer) FINDINGS:

This study, the second review of 5,136 biopsy samples found that

diagnosis changed in 11 percent (1.1 percent from benign to malignant,

1.2 percent from malignant to benign, and 8 percent had a change in

doctors' ranking of how abnormal the cells were) of the samples over

time, suggesting a not insignificant initial error rate.STUDY: Perlis (2005)CONDITION: Bipolar disorder FINDINGS:

The initial diagnosis was wrong in 69 percent of patients with bipolar

disorder and delays in establishing the correct diagnosis were common.STUDY: Graff et al (2000)CONDITION: Appendicitis (inflamed appendix) FINDINGS:

Retrospective study at 12 hospitals of patients with abdominal pain and

operations for appendicitis. Of 1,026 patients who had surgery, there

was no appendicitis in 110 (10.5 percent); of 916 patients with a final

diagnosis of appendicitis, the diagnosis was missed or wrong in 170

(18.6 percent).STUDY: Raab et al (2005)CONDITION: Cancer pathology (microscopic examination of tissues and cells to detect cancer) FINDINGS:

The frequency of errors in diagnosing cancer was measured at four

hospitals over a one-year period. The error rate of pathologic

diagnosis was 2 percent to 9 percent for gynecology cases and 5 percent

to 12 percent for nongynecology cases; errors ran from what tissues the

doctors used, to preparation problems, to misinterpretations of tissue

anatomy when viewed under microscope.STUDY: Buchweitz et al (2005)CONDITION: Endometriosis (tissue similar to the lining of the uterus is found elsewhere in the body) FINDINGS:

Digital videotapes of the inside of patients' bodies were shown to 108

gynecologic surgeons. Surgeons agreed only 18 percent of the time as to

how many tissue areas were actually affected by this condition.STUDY: Gorter et al (2002)CONDITION: Psoriatic arthritis (red, scaly skin coupled with join inflammation) FINDINGS:

One of two patients with psoriatic arthritis visited 23 joint and motor

specialists; the diagnosis was missed or wrong in nine visits (39

percent).STUDY: Bogun et al (2004)CONDITION: Atrial fibrillation (abnormal heart beat in the upper chambers of the heart) FINDINGS:

Review of doctor readings of electro-cardiograms [a graphical recording

of the change in body electricity due to cardiac activity] that

concluded a patient suffered from this abnormal heart beat found that:

35 percent of the patients were misdiagnosed by the machine, and the

error was detected by the reviewing clinician only 76 percent of the

time.STUDY: Arnon et al (2006)CONDITION: Infant botulism (toxic bacterial infection in newborns' intestines) FINDINGS:

Study of 129 infants in California suspected of having botulism during

a five-year period; only 50 percent of the cases were suspected at the

time of admission.STUDY: Edelman (2002)CONDITION: Diabetes (high blood sugar due to insufficient insulin) FINDINGS:

Retrospective review of 1,426 patients with laboratory evidence of

diabetes showed that there was no mention of diabetes in the medical

record of 18 percent of patients.STUDY: Russell et al (1988)CONDITION: Chest x-rays in the emergency department FINDINGS:

One third of x-rays were incorrectly interpreted by the emergency

department staff compared with the final readings by radiologists.OverconfidenceMisdiagnosis rarely springs from a "lack of knowledge per se,

such as seeing a patient with a disease that the physician has never

encountered before," Berner and Grave explain. "More commonly,

cognitive errors reflect problems gathering data, such as failing to

elicit complete and accurate information from the patient; failure to

recognize the significance of data, such as misinterpreting test

results; or most commonly, failure to synthesize or 'put it all

together.'"The breakdown in clinical reasoning often occurs

because the physician isn't willing or able to "reflect on [his] own

thinking processes and critically examine [his] assumptions, beliefs,

and conclusions." In a word, the physician is too "confident."Indeed,

Berner and Graber find an inverse relationship between confidence and

skill. In one study they reviewed, the researchers looked at diagnoses

made by medical students, residents and physicians, and asked them how

certain they were that they were correct. The good news is that while

medical students were less accurate, they also were less confident;

meanwhile the attending physicians were the most accurate and highly

confident. The bad news is that the residents were more confident than

the others, but significantly less accurate than the attending

physicians. In another study, researchers found that residents often

stayed wedded to an incorrect diagnosis even when a diagnostic decision

support system suggested the correct diagnosis.In a third study

of 126 patients who died in the ICU and underwent autopsy, physicians

were asked to provide the clinical diagnosis and also their level of

uncertainty. Level 1 represented complete certainty, level 2 indicated

minor uncertainty, and level 3 designated major uncertainty. Here the

punch line is alarming: Clinicians who were "completely certain" of the

diagnosis before death were wrong 40 percent of the time.Overconfidence,

or the belief that "I know all I need to know," may help explain what

the researchers describe as a "pervasive disinterest in any decision

support or feedback, regardless of the specific situation." Studies

show that "physicians admit to having many questions that could be

important at the point of care, but which they do not pursue. Even when

information resources are automated and easily accessible at the point

of care with a computer, one study found that only a tiny fraction of

the resources were actually used."Research shows that physicians

tend to ignore computerized decision-support systems, often in the form

of guidelines, alerts and reminders. "For many conditions, consensus

exists on the best treatments and the recommended goals," Berner and

Graber point out. Nevertheless, a comprehensive review of medical

practice in the United States found that the care provided deviated

from recommended best practices half of the time. In one study, the

researchers suggest that the high rate of noncompliance with clinical

guidelines relates to "the sociology of what it means to be a

professional" in our health care system: "Being a professional connotes

possessing expert knowledge in an area and functioning relatively

autonomously." Many physicians have yet to learn that 21st century

medicine is too complex for anyone to know everything -- even in a

single specialty. Medicine has become a team sport.But while

it's easy to blame medical "arrogance" for the high rate of errors,

"there is ubstantial evidence that overconfidence -- that is,

miscalibration of one's own sense of accuracy and actual accuracy -- is

ubiquitous and simply part of human nature," Berner and Graber write.

"A striking example derives from surveys of academic professionals, 94

percent of whom rate themselves in the top half of their profession.

Similarly, only 1 percent of drivers rate their skills below that of

the average driver."In another study published in the same issue of AMJ, Pat Croskerry and Geoff Norman note

that such equanimity regarding one's own skills can lead to what's

called "confirmation bias." People "anchor" on findings that support

their initial assumptions. Given a set of information, it's much easier

to pull out the data that proves you right and pat yourself on the back

than it is to look at the contradictory evidence and rethink your

assumptions. Indeed, Croskerry and Norman observe,"It takes far more

mental effort to contemplate disconfirmation -- by considering all the

other things it might be -- than confirmation."Making things all

the more difficult is the fact that, at a certain point, the

alternative to confirmation bias -- what Croskerry and Norman call

"consider the opposite" -- becomes impractical. If a doctor embraces

uncertainty, he could easily become paralyzed.What doctors need

to do is to simultaneously make a decision -- and keep an open mind.

Often, a doctor must embark on a course of treatment as a way of

diagnosing the condition -- all the time knowing that he may be wrong.Too

often, Berner and Graber observe, physicians narrow the diagnostic

hypotheses too early in the process, so that the correct diagnosis is

never seriously considered. Reliance on advanced diagnostic tests can

encourage what they call "premature closure." After all, high-tech

diagnostic technologies offer up hard-and-fast data, fostering the

illusion that the physician has vanquished medicine's ambiguity.But

in truth, advanced diagnostic tools can miss critical information. The

problem is not the technology, but how we use it. Some observers

suggest that the newest and most sophisticated tools are more likely to

produce false negatives because doctors accept the results so readily."In most cases, it wasn't the technology that failed," explains Dr. Atul Gawande in Complications: A Surgeon's Notes on an Imperfect Science.

"Rather, the physician did not consider the right diagnosis in the

first place. The perfect test or scan may have been available, but the

physician never ordered it." Instead, he ordered another test -- and

believed it."We get this all the time," Bill Pellan of Florida's Penallas-Pasca County Medical Examiner's Office told the New York Times

a few years ago. "The doctor will get our report and call and say: 'But

there can't be a lacerated aorta. We did a whole set of scans.'"We have to remind him we held the heart in our hands."AutopsiesSometimes

physicians are overly confident; sometimes they narrow their hypothesis

too early in the diagnostic process. Sometimes they rely too heavily on

advanced diagnostic tests and accept the results too quickly. As I

explained in part one of this post, these are some of the reasons why

physicians misdiagnose their patients up to 15 percent of the time."Complacency"

(i.e., the attitude that "nobody's perfect") also is a factor, reports

Drs. Eta S. Berner and Mark L. Graber in the May issue of the American Journal of Medicine.

"Complacency reflects tolerance for errors, and the belief that errors

are inevitable," they write, "combined with little understanding of how

commonplace diagnostic errors are. Frequently, the complacent physician

may think that the problem exists, but not in his own practice ..."It

is crucial to recognize that physicians are not simply deceiving

themselves: In our fragmented healthcare system, many honestly don't

know when they have misdiagnosed a patient. No one tells them --

including the patient.Sometimes a patient who isn't getting

better simply leaves the doctor and finds someone else. His original

doctor may well assume that he was finally cured. Or the patient may be

discharged from the hospital, relapse three months later, and go to a

different ER where he discovers that his symptoms have returned because

he was, in fact, misdiagnosed. The doctors who cared for him at the

first hospital have no way of knowing; they think they cured him. In

other cases, the patient gets better despite the wrong diagnosis. (It

is surprising how often bodies heal themselves.) Meanwhile, both doctor

and patient assume that the diagnosis was right and that the treatment

"worked."In still other cases, the patient dies, and because

everyone assumes that the diagnosis was correct, it is listed as the

"cause of death" -- when in fact, another condition killed the patient.When

giving talks to groups of physicians on diagnostic errors, Graber says

that he frequently "asks whether they have made a diagnostic error in

the past year. Typically, only 1 percent admit to having made such a

mistake."Here, we reach the heart of the problem: what Berner

and Graber call "the remarkable discrepancy between the known

prevalence of diagnostic error and physician perception of their own

error rate." This gap "has not been formally quantified and is only

indirectly discussed in the medical literature," they note "but [it]

lies at the crux of the diagnostic error puzzle and explains in part

why so little attention has been devoted to this problem."One

cannot expect doctors to learn from their mistakes unless they have

feedback: At one time, autopsies provided physicians with the

information they needed. And the results were regularly discussed at

"mortality and morbidity" conferences, where doctors became

Monday-morning quarterbacks, discussing what they could have done

differently.But today, "autopsies are done in 10 percent of all deaths; many hospitals do none," notes Dr. Atul Gawande in Complications: A Surgeons Notes on an Imperfect Science.

"This is a dramatic turnabout. Throughout much of the 20th century,

doctors diligently obtained autopsies in the majority of all deaths ...

Autopsies have long been viewed as a tool of discovery, one that has

been used to identify the cause of tuberculosis, reveal how to treat

appendicitis and establish the existence of Alzheimer's disease."So

what accounts for the decline?" Gawande asks. "In truth, it's not

because families refuse -- to judge from recent studies, they still

grant their permission up to 80 percent of the time. Instead, doctors

once so eager to perform autopsies that they stole bodies [from graves]

have simply stopped asking."Some people ascribe this to shady

motives," Gawande continues. "It has been said that hospitals are

trying to save money by avoiding autopsies, since insurers don't pay

for them, or that doctors avoid them in order to cover up evidence of

malpractice. And yet," he points out, "autopsies lost money and

uncovered malpractice when they were popular, too."Gawande

doesn't believe that fear of malpractice has driven the decline in

autopsies. Instead," he writes, "I suspect, what discourages autopsies

is medicine's 21st century, tall-in-the-saddle confidence."This

is an important point. Autopsies have fallen out of fashion in recent

years: "Between 1972 and 1995, the last year for which statistics are

available, the rate fell from 19.1 percent of all deaths to 9.4

percent. A major reason for the decline over this period is that

"imaging technologies such as CT scanning and ultrasound have enabled

doctors to 'see' such obvious internal causes of death as tumors before

the patient dies," says

Dr. Patrick Lantz, associate professor of pathology at Wake Forest

University Baptist Medical Center. Nowadays an autopsy seems a waste of

time and resources.Gawande agrees: "Today we have MRI scans,

ultrasound, nuclear medicine, molecular testing and much more. When

somebody dies, we already know why. We don't need an autopsy to find

out ... Or so I thought ... " Gawande then goes on to tell the story of

a autopsy that rocked him. He had completely misdiagnosed a patient.What autopsies showThe

autopsy has been described as "the most powerful tool in the history of

medicine" and the "gold standard" for detecting diagnostic errors.

Indeed, Gawande points out that three studies done in 1998 and 1999

reveal that autopsies "turn up a major misdiagnosis in roughly 40

percent of all cases."A large review of autopsy studies

concluded that, "in about a third of the misdiagnoses, the patients

would have been expected to live if proper treatment had been

administered," Gawande reports. "Dr. George Lundberg, a pathologist and

former editor of the Journal of the American Medical Association,

has done more than anyone to call attention to these figures. He points

out the most surprising fact of all: The rate at which misdiagnosis is

detected in autopsy studies have not improved since at least 1938."When

Gawande first heard these numbers he couldn't believe them. "With all

of the recent advances in imaging and diagnostics ... it's hard to

accept that we have failed to improve over time." To see if this really

could be true, he and other doctors at Harvard put together a simple

study. They went back into their hospital records to see how often

autopsies picked up missed diagnosis in 1960 and 1970, before the

advent of CT, ultrasound, nuclear scanning and other technologies, and

then in 1980, after those technologies became widely used.Gawande

reports the results of the study: "The researchers found no

improvement. Regardless of the decade, physicians missed a quarter of

fatal infections, a third of heart attacks and almost two-thirds of

pulmonary emboli in their patients who died."But these numbers

may exaggerate the rate of error. As Berner and Graber observe,

"Autopsy studies only provide the error rate in patients who die." One

can assume that the error rate is much lower in patients who survived."For

example, whereas autopsy studies suggest that fatal pulmonary embolism

is misdiagnosed approximately 55 percent of the time, the misdiagnosis

rate for all cases of pulmonary embolism is only 4 percent ..." a large

discrepancy also exists regarding the misdiagnosis rate for myocardial

infarction: although autopsy data suggest roughly 20 percent of these

events are missed, data from the clinical setting (patients presenting

with chest pain or other relevant symptoms) indicate that only 2

percent to 4 percent are missed."Still, they acknowledge that

when laymen are trained to pretend to be a patient suffering from

specific symptoms, studies show that "internists missed the correct

diagnosis 13 percent of the time. Other studies have found that

physicians can even disagree with themselves when presented again with

a case they have previously diagnosed."On the question of

whether the diagnostic error rate has changed over time, Berner and

Graber quote researchers who suggest that the near-constant rate of

misdiagnosis found at autopsy over the years probably reflects two

factors that offset each other:diagnostic accuracy actually has improved over time (more knowledge, better tests, more skills);but

as the autopsy rate declines, there is a tendency to select only the

more challenging clinical cases for autopsy, which then have a higher

likelihood of diagnostic error. A long-term study of autopsies in

Switzerland (where the autopsy rate has remained constant at 90

percent) supports the theory that the absolute rate of diagnostic

errors is, as suggested, decreasing over time. Nevertheless, nearly everyone agrees, the rate of diagnostic errors remains too high.We

need to revive the autopsy, Gawande argues. For "autopsies not only

document the presence of diagnostic errors, they also provide an

opportunity to learn from one's errors (errando discimus) if one takes

advantage of the information."The rate of autopsy in the United

States is not measured anymore," he observes, "but is widely assumed to

be significantly 10 percent. To the extent that this important feedback

mechanism is no longer a realistic option, clinicians have an

increasingly distorted view of their own error rates."Autopsy

literally means "to see for oneself," Gawande observes, and despite our

knowledge and technology, when we look we are often unprepared for what

we find. Sometimes it turns out that we had missed a clue along the way

or made a genuine mistake. Sometimes we turn out wrong despite doing

everything right."Whether with living patients or dead, we

cannot know until we look. ... But doctors are no longer asking such

questions. Equally troubling, people seem happy to let us off the hook.

In 1995, the United States National Center for Health Statistics

stopped collecting autopsy statistics altogether. We can no longer even

say how rare autopsies have become."If they are going to reflect on their mistakes, physicians need to "see for themselves."

 

 

Maggie Mahar is a fellow at the Century Foundation and the author of Money-Driven Medicine: The Real Reason Health Care Costs So Much (Harper/Collins 2006).Niko

Karvounis is a program officer with the Century Foundation in New York

City, where he works on issues of socioeconomic inequality and

healthcare. He is a regular contributor to Health Beat, the

foundation's healthcare blog.