Evidence-based medicine?
- From: Steve <mft@xxxxxxx>
- Date: Fri, 19 May 2006 14:30:02 -0700
Excerpts from
http://www.businessweek.com/magazine/content/06_22/b3986001.htm
Even today, with a high-tech health-care system that costs the nation
$2 trillion a year, there is little or no evidence that many widely
used treatments and procedures actually work better than various
cheaper alternatives. This judgment pertains to a shocking number of
conditions and diseases, from cardiovascular woes to back pain to
prostate cancer.
During his long and controversial career proving that the practice of
medicine is more guesswork than science, Dr. David Eddy has repeatedly
punctured cherished physician myths. He showed, for instance, that the
annual chest X-ray is worthless. He proved that doctors had little
clue about the success rate of procedures such as surgery for enlarged
prostates. He traced one common practice - preventing women from
giving birth vaginally if they had previously had a cesarean - to the
recommendation of one lone doctor.
When he began taking on medicine's sacred cows, Eddy liked to cite a
figure that only 15% of what doctors did was backed by hard evidence.
A great many doctors and health-care quality experts have come to
endorse Eddy's critique. And while there has been progress in recent
years, most of these physicians say the portion of medicine that has
been proven effective is still outrageously low, in the range of
20-25%.
The human brain needs help to make sense of patients who have
combinations of diseases, and of the complex probabilities involved in
each. To provide that assistance, Eddy has spent the past ten years
leading a team to develop the computer model that helped him crack the
diabetes puzzle. The conventional approach to treating diabetes did
little to prevent the heart attacks and strokes that are complications
of the disease. In contrast, a simple regimen of aspirin and generic
drugs to lower blood pressure and cholesterol sent the rate of such
incidents plunging.
Dubbed Archimedes, this program seeks to mimic in equations the actual
biology of the body, and make treatment recommendations as well as
figure out what each approach costs.
Eddy used his math skills to model cancer screening. His PhD thesis
made front-page news in 1980 by overturning the guidelines of the
time. It showed that annual chest X-rays and yearly Pap smears for
women at low risk of cervical cancer were a waste of resources. Based
on his results, the American Cancer Society changed its guidelines.
Meanwhile, he carved out a niche showing doctors at specialty society
meetings that their cherished beliefs were dubious. At each meeting he
would do the same exercise - ask doctors to think of a typical patient
and typical treatment, then write down the results of that treatment.
The results were startling. The predictions of success invariably
ranged from 0-100%, with no clear pattern. All the doctors were trying
to estimate the same thing and they all gave different numbers.
"I've spent 25 years proving that what we lovingly call clinical
judgment is woefully outmatched by the complexities of medicine. Think
about the implications for helping patients make decisions. Go to one
doctor and get one answer. Go to another and get a different one. Or
think about expert testimony. You don't have to hire an expert to lie.
You can just find one who truly believes the number you want."
Take prostate cancer. Doctors now routinely test for levels of PSA to
try to diagnose the disease. But there's no evidence that using the
test improves survival. Some experts believe that as many cancers
would be detected through random biopsies. Then, once cancer is
spotted, there's no way to know who needs treatment and who doesn't.
Plus, there is a plethora of treatment choices - four kinds of
surgery, various types of implantable radioactive seeds, and competing
external radiation regimens.
How is a patient supposed to decide among those? Most of the time,
patients don't even know the options. Because there are no definitive
answers, you are at the whim of where you are and who you talk to. Go
to a surgeon and he'll probably recommend surgery. Go to a
radiologist, and the chances are you'll get radiation instead.
The bottom line: The conventional wisdom in prostate cancer - that
surgery is the gold standard and the best chance for a cure - is
unsustainable. But the choice may not matter very much. There isn't
good evidence to suggest that one treatment is better than another.
Many physicians now concur that traditional treatments for serious
illnesses often aren't best. Yet this message can be hard for people
to believe. The message flies in the face of America's infatuation
with the latest advances.
New radiation machines for cancer, or operating rooms for heart
surgery, are profit centers for hospitals. Once a hospital installs a
shiny new catheter lab, it has a powerful incentive to refer more
patients for the procedure. It's a classic case of supply driving
demand, instead of the other way around. Combine that with Americans'
demand to be treated immediately, and it is a cauldron for overuse and
inappropriate use.
The consequences for the US are disturbing. This nation spends 2.5
times as much per person on health care, compared to other countries.
There is a massive amount of spending on things that don't help
patients, and even put them at greater risk.
Even when common treatments are proved to be dubious, physicians don't
rush to change their practice. They may still firmly believe in the
treatment - or in the dollars it brings in.
With proof about medical outcomes lacking, one possible solution is
educating patients about the uncertainties. The popular version of
evidence-based medicine is about proving things, but it is really
about transparency - being clear about what we know and don't know.
In studies where one group of patients hears the full story while
other patients simply receive their doctors' instructions, a key
difference emerges. The well-informed patients are 23% less likely
(and in some studies 50-60% less likely) to opt for more invasive,
aggressive approaches. Patients typically don't understand that they
have options, and even if they do, they often exaggerate the benefits
of surgery and minimize the chances of harm.
Eddy's computer simulation could help more patients attain appropriate
care. His approach is to create a world where virtual doctors conduct
trials of virtual patients and figure out what treatments work.
After getting funding from Kaiser Permanente in 1991, Eddy hired a
particle physicist, Len Schlessinger, who knew how to write equations
describing the complex interactions in biology. The pair selected
diabetes as a test case.
In their virtual world, each simulated person has a heart, liver,
kidneys, blood, and other organs. As in real people, cells in the
pancreas make insulin, which regulates the uptake of glucose in other
cells. And as in the real disease, key cells can fail to respond to
the insulin, causing high blood-sugar levels and a cascade of
biological effects. The virtual patients come down with high blood
pressure, heart disease, and poor circulation, which can lead to foot
ulcers and amputations, blindness, and other ills. The model also
assesses the costs of treating the complications.
Eddy dubbed the model Archimedes and tested it by comparing it with
two dozen real trials. One clinical study compared
cholesterol-lowering statin drugs to a placebo in diabetics. After 4.5
years, the drugs reduced heart attacks by 35%. The exact same thing
happened in Eddy's simulated patients.
The team then put Archimedes to work on a tough, real problem - how
best to treat diabetes in people who have additional aliments. Doctors
now typically try to treat the most pressing problems. But they fail
to pick the right ones consistently, resulting in misdirected
utilization and a great deal of waste.
Kaiser Permanente's Dr. Jim Dudl had a counterintuitive suggestion.
With diabetics, doctors assume that keeping blood sugar levels low and
consistent is the best way to ward off problems such as heart disease.
But Dudl wondered what would happen if he flipped it around, aiming
treatment at the downstream problems. The idea is to give patients a
trio of generic medicines - aspirin, a cholesterol-lowering statin,
and drugs called ACE inhibitors.
Using Archimedes and thousands of virtual patients, Eddy and
Schlessinger compared the traditional approach with the drug
combination. The model took about a half-hour to simulate a 30-year
trial, and showed that the three-drug combination was cost and
life-saving. The benefits far surpassed what can be achieved with
aggressive glucose control. It is too early to declare a victory, but
the experience with patients seems to be mimicking Eddy's computer
model. It goes against our mental picture of the disease. But it also
makes sense. Cardiovascular disease is the worst complication of
diabetes - it's what people die of.
The modeling approach allows each of us, in essence, to have an
imaginary twin. We can use our twin to predict what our lives and
state of health are likely to be with different lifestyles and
approaches to care.
Eddy's mission is that in ten years, no one will make an important
decision in health care without first asking: What does Archimedes
say?
--
The only reason some people get lost in thought is because it's unfamiliar territory.
....Paul Fix
.
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