The Startling Truth About Doctors And Diagnostic Errors



The Startling Truth About Doctors and Diagnostic Errors
By Maggie Mahar and Niko Karvounis, Health Beat

Posted on June 19, 2008, Printed on June 20, 2008
http://www.alternet.org/story/88515/
This article originally appeared on Health Beat.

Despite 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.

Overconfidence

Misdiagnosis 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."

Autopsies

Sometimes 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 show

The 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.

© 2008 Health Beat All rights reserved.
View this story online at: http://www.alternet.org/story/88515/
.

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