What Doctors Don't Know (Almost Everything)
By KEVIN PATTERSON, May 5, 2002
I work as an internist in the Canadian Arctic, in a region called Kivalliq, on the west coast of Hudson Bay. There are no highways there, and the more recent social changes of the south have not penetrated the tundra any more deeply than the road system has. The eyewear is distinctly out of fashion, and the church remains influential.
In Kivalliq, interaction between patients and physicians is not characterized by lengthy debate. People expect to receive prescriptions and proscriptions; these are provided, and patients generally keep their opinions to themselves. It is the postcolonial era, but not by much.
I also work on Vancouver Island, and there, the eyewear is outlandish and churches are being sued everywhere. The interaction between patients and physicians, however, is the least different thing about the two places. There is somewhat more dialogue in the south, to be sure, but the tone of the interaction is for the most part lodged in the Edwardian era. You must stop smoking. If you don't lose weight, you're destined for diabetes. You have congestive heart failure. Here is a prescription for the drugs you need to take; please don't forget. The finger wagging is unceasing.
Medicine has clung to a sense of hierarchy that is being abandoned elsewhere. Teachers answer to parents and bankers solicit borrowers, but in medicine, a chain of command has existed since the profession found its modern face -- doctor's orders -- with the most senior and academic physician experts directing the decisions of specialists, family physicians and ultimately the patients.
This order is now in the throes of a revolution known as evidence-based medicine, which asserts the supremacy of data over authority and tradition. For doctors these days, the revolution is everywhere; you can't kick over a bedpan without hearing the phrase ''evidence-based medicine'' rattle out. Outside the hospital walls, though, word has been slower to travel.
E.B.M. is, as revolutions go, a little unlikely. Its motives are not primarily political, although its effects ultimately are. And those effects -- the various ways in which information subverts hierarchy -- are beginning to change medicine fundamentally. What began as a pragmatic undertaking has become a philosophical and political transformation, and it is creating a dramatic shift in the relationship between doctors and patients.
Until recently, the guiding principle in medicine has been Aristotelian: an understanding of the disease comes first, before experimentation. On the face of it, the approach isn't outrageous; doctors try to understand the nature of the ailment they are addressing, and then they try to think of an intervention -- an operation or a pill or a type of psychotherapy -- that goes to the essence of the problem. And this method often works. For instance, when Frederick G. Banting and Charles H. Best identified the role a deficiency of insulin played in the development of juvenile diabetes, the treatment that suggested itself -- replacing the insulin -- turned out to be a huge success. Banting and Best's discovery was a model of how medicine advanced through most of the 20th century. Research was based on this simple, rational premise: understand the problem, and its solution will become self-evident.
But people, doctors included, have a tendency to see what they expect to see. It's the premise of every sleight-of-hand game. If it makes sense that a treatment will work -- or if one stands to make money if a treatment works -- then a doctor will, with alarming and disheartening reliability, perceive that it does in fact work. What is surprising is that a profession that dresses itself up in the garb of science has taken so long to acknowledge a principle that every small-town carny understands.
When I started practicing medicine in the early 90's, one of my enthusiasms was hormone-replacement therapy. At that time, the observation had been made, repeatedly, that postmenopausal women who happened to take estrogen -- for osteoporosis or hot flashes, for instance -- were less likely to have heart attacks and strokes than women who didn't. I remember telling women in their 50's how premenopausal women were relatively immune to cardiovascular disease, at least compared with men, but that once they had been through menopause, this relative protection disappeared quickly. ''Take the estrogen,'' I suggested over and over. ''Preserve your youthful coronaries.''
This was in Manitoba, and these were pragmatic, sensible prairie women. I insisted to them that the recommendations and the evidence seemed clear. I remember my patients' brows knitting at the thought of menstrual cycles extending into their dotage, but ultimately the argument felt compelling. Certainly it did for me. I remembered being told in medical school that the underuse of estrogen was one of the great crimes of the medical patriarchy, itself an expression of latent misogyny. No misogynist I, off I went to work, my prescription pad leaping to hand at the sight of bifocals or pastel cardigans.
Then in 1998, the results of a formal, placebo-controlled clinical trial called the Heart and Estrogen/Progestin Replacement Study (HERS) were published. It showed that estrogen did not prevent heart attacks or strokes and, in fact, it made women more susceptible to blood clots. The net cardiovascular effect therefore was negative. This study astonished most doctors -- for me, it certainly felt like a betrayal. Betrayed by the recommendations, we had in turn betrayed many of the cardigan-clad women of our acquaintance.
A few months ago, in the emergency room of one of the hospitals I work in on Vancouver Island, I saw a woman in her mid-70's who was still taking Premarin, a common estrogen preparation. She had been having chest pain, and I was admitting her for observation, to make sure she wasn't having a heart attack.
''So, you take the Premarin because . . . ?'' I asked.
''My sisters all had heart attacks in their 50's,''she said. ''My doctor said the estrogen lowered my risk.''
''We now think it probably doesn't.''
''Really.''
''Yes.'' Me, nodding, smiling weakly.
''What changed?''
''Well, there were these studies that seemed to show that women who took estrogen had a relatively low incidence of heart attacks, but it turns out that really, it was the sort of woman who took estrogen who was less likely to have a heart attack. She was probably also less likely to smoke, more likely to seek regular medical attention -- she did something important different, anyway. When, just recently, they took a large group of women and randomly gave each woman either a placebo or estrogen, the ones taking estrogen didn't do at all better.''
''Well,'' she said. ''Isn't that something?''
My patient was not alone. The data from HERS were so surprising that many health-care providers seem not to believe them, even today. In 2001, Premarin was the third most-prescribed drug in the United States.
Until only a few generations ago, the prevailing conception of illness was that the sick were contaminated by some toxin or contagion or an excess of one humor or another. That understanding of illness contained within it the idea that these conditions could be improved by opening a vein and letting the sickness run out: bloodletting, the practice was called.
Once the toxins were gone, the patient immediately felt different, and often better. As anyone who has given blood can tell you, losing a pint or two can make you feel transported, transformed. Intuitively, it was satisfying to doctors that the procedure left the patient feeling drained -physically, emotionally and into the sink.
It is understood now that bloodletting only hastened the death of the ill. (George Washington had almost five pints of blood drained from him in the two days prior to his death; he had been suffering from a sore throat.) We know that bloodletting is unhelpful because a Parisian doctor named Pierre Louis did an experiment in 1836 that is now recognized as one of the first clinical trials. He treated people with pneumonia either with early, aggressive bloodletting or less aggressive measures; at the end of the experiment, Dr. Louis counted the bodies. They were stacked higher over by the bloodletting sink.
No sooner had the message about the dangers of draining blood out of patients been conveyed across the medical community -- and that took the rest of the 19th century -- than doctors developed a new passion for pouring it back into them. After crosstyping was invented and blood could be transfused safely, doctors quickly decided that very ill patients do better with as normal a level of hemoglobin as could be maintained. It made sense, and blood transfusions became a routine part of critical-care medicine.
Then just three years ago the results of a large study called Transfusion Requirements in Critical Care were published in The New England Journal of Medicine. Those results shook the community of intensive-care physicians worldwide. Except in the case of people with unstable angina and acute myocardial infarction, routine transfusion of critically ill people with moderate or mildly low hemoglobin levels does not decrease their mortality rate -- and in some subgroups, it actually increases the mortality rate. Nobody has a convincing explanation for why this is, but it is the case.
The essential tenet of evidence-based medicine is that patients, working with their physicians and armed with medical data, are better equipped to make decisions that work for them than doctors of the Marcus Welby model are, because they understand their own expectations better than their physicians can. Authority is devolved from expertise to the data and thus, ultimately, to the patient. In an E.B.M. world, the physician makes diagnoses, serves as a conduit of the medical data and is responsible for framing those data and putting them into context, but the responsibility for the decision becomes the patient's. Patients have always had the final say about whether to accept the recommendations of their physicians, but without the actual data in front of them, the decision has simply been whether or not to trust the wisdom of the physician. E.B.M. tries to move that judgment to the steadier ground of data.
The point isn't that some medical treatments don't work as well as it is thought, or even that in treating patients, doctors sometimes hurt them -- this has always been true. The point is that the conclusions doctors reach from clinical experience and day-to-day observation of patients are often not reliable. The vast majority of medical therapies, it is now clear, have never been evaluated by systematic study and are used simply because doctors have always believed that they work.
The manifesto of the evidence-based-medicine movement appeared in The Journal of the American Medical Association in 1992, written by a group of doctors led by an internal-medicine specialist in Hamilton, Ontario, named Gordon H. Guyatt. The publication ignited a debate about power, ethics and responsibility in medicine that is now threatening to radically change the experience of health care.
''If you said to most members of the general public, 'Physicians have been trained in such a manner that they have no idea how to read a paper from the original medical literature or how to interpret it,' that would surprise the public,'' Guyatt says. ''The public's image of physicians has been such that it would be shocking to them that there hasn't always been evidence-based practice.''
From the first day in the cadaver room and on, every medical student is drilled with this truism: ''Medicine is both an art and a science.'' The ''art'' is represented to be the physician's intuitive sense of a patient and her underlying diagnoses and how she might respond to certain treatments.
And intuition is certainly an indispensable part of medicine. The body is so complex, and the ways it might go wrong so varied, that in the middle of the night, standing next to some fresh catastrophe, a doctor sometimes needs to generalize and to reduce very complicated problems to first principles. It is simply not possible to be rigorously intellectual and consult the available medical data about every single thing, all the time. It takes too long, and if all the intricacies of the medical data on every clinical problem were fully considered before acting, the operating rooms would grow dusty and people would die while the doctors' chins were rubbed into a bright shine. Sometimes it is necessary to act on a feeling.
And so medicine has intellectual shortcuts: intuitions and axioms and rules of thumb: ''Never let the sun set on an abscess'' (operate early when you find one) or on a more particular note, ''Gerald hasn't looked right for months now; this isn't just a cold.''
The feeling, the art, is precisely what is appealing about medicine for doctors. It is personal and warm, and dramatic, pithy platitudes about the indications for surgery are easier to remember and more satisfying to cite than the constantly changing and dry data on outcomes. But in the end, the art is simply what one wants it to be. And if a doctor simply feels that blood transfusions are good for people with pneumonia, should that be enough reason to transfuse them?
The answer has always been, pretty much, yes. Clinical impressions do matter and ought to be taken seriously. When an experienced neonatology nurse doesn't like the look of an infant, for instance, a pediatrician takes that very seriously, or quickly learns to, even if there is no fever or abnormal lab results. It sounds a little like magic, this art. And once you believe a little in magic, it's hard to imagine there's anything it can't do.
Nuala Kenny, a physician-ethicist at Dalhousie University in Halifax, Nova Scotia, and a critic of evidence-based medicine, defends intuitive reasoning: it isn't a lazy way of thinking, she argues, but rather a sophisticated type of thought that incorporates many variables and tremendous amounts of data from previous experience. It's the reason that Kasparov can still beat Deep Blue from time to time.
''Scientific data cannot be expected to guide most medical decisions directly,'' she wrote in one critique. ''There are not enough randomized trials or epidemiologic studies; there are virtually no studies on appropriate ordering of tests. The randomized clinical trial has become the gold standard but . . . it is a leap of faith to expand the results of a trial to a broad therapeutic principle. Clinicians recognize this instinctively. The best drug, the optimal dose and duration of therapy for a particular patient are not determined directly by a study involving a large population.''
Kenny sees E.B.M. as a threat to the individual practitioner, another step toward the mechanization of medicine. Guyatt emphasizes that E.B.M. gives the individual practitioner the tools to defend iconoclastic practice with data. E.B.M. represents a more skeptical approach to practicing medicine, but at the same time a more open one, Guyatt argues. If the data support an intervention, even if it is herbal or crystal-based or otherwise magical-seeming, then the intervention should be put into practice. St. John's Wort, for instance, has been demonstrated to be an antidepressant of modest potency in randomized clinical trials and thus, in the E.B.M. worldview, there is nothing ''alternative'' about it.
The disagreement is really over the value of intuition: the E.B.M. position is that there are reliable, validated data, and then there are data that aren't reliable and validated, and that's really what matters. This difference may never be resolved through debate; it might be the difference between having faith and not having it.
The most radical change E.B.M. proposes will occur in everyday visits in doctor's offices -- those simple, scary moments when the most important medical decisions are made. The instant the practitioner stops saying, ''I think you should take this therapy,'' and starts saying, ''The evidence is that this therapy will work this percent of the time, with these complications, this frequently; what do you want to do?'' then the power hierarchy of doctor over patient is collapsed, and autonomy is assigned to the patient. This is how the relationship between doctor and patient could be changed by evidence-based medicine. Just as the idea of authority within medicine is rejected, so too, the idea of the profession of medicine itself having authority over the patient is rejected. Giving authority to the data, instead of other people, empowers everyone, the movement holds.
It isn't clear that patients will embrace evidence-based medicine. Human beings are social creatures, and we don't necessarily want to have to make up our own minds about absolutely everything, especially if doing so requires trips to the library and afternoons on the Internet and hours of reflection.
Practitioners are also resistant to E.B.M., simply because it marks a change in the idea of what doctors are. It is a signal that in medicine, ours is a less heroic age. The dramatic cures have stopped coming. Penicillin for meningitis, streptomycin for tuberculosis, Salk and polio: what those days of discovery must have been like, with self-evident cures trotting forth regularly for all the old killers. Everyone used to die of this, now almost everyone recovers -- the only trick is in making the diagnosis. How satisfying it must have been, how easy to feel potent.
Now we die of things like congestive heart failure: diseases that haven't submitted to easy, magic-bullet cures and have the habit of announcing their presence quietly when they are already well advanced. These diseases are pared away incrementally, the mortality rate decreased by a few percentage points with this maneuver, a few more with that one. A number of things help a bit; nothing helps a lot.
So the warriors are being replaced by the accountants. The 28 percent response rate is traded for the 31 percent response rate; differences in effectiveness that are too subtle to be noticed by an individual practitioner justify ongoing refinements in therapy. The numbers dictate the changes, and each year the outlook is slightly better.
Accountants know the whole world thinks their lives are gray -- demeaned by all that addition. Doctors aren't used to thinking of themselves that way. But in the real world, where numbers matter, accountants know how powerful they are. Doctors now have to learn the same lesson.
No one knows where the ongoing renegotiation of the complicated relationship between the individual and society, which lies at the heart of E.B.M., is going to end. At the same time that the individual increasingly demands control of his life, money and expression, he also clearly still wants to be protected by society from corporate interests and economic vagaries, and to be taken care of when he is sick. This ambivalence about independence is an essentially human trait, as is a certain ambivalence about empiricism itself. The story is as old, and Greek, as the Hippocratic tradition itself: what empowers us sometimes demeans us.
Kevin Patterson is an internist and the author of ''The Water in Between: A Journey at Sea.''
