Here is another post about using medical evidence. My last one dealt with the usefulness (or not) of expert opinion as a basis for evaluating the validity of a medical claim. This post discusses the next highest item on the hierarchy of medical evidence — the case report.

The simple case description is the oldest tradition in medical research, dating back hundreds of years, long before biostatistics had even been thought of. The medical journals of the nineteenth and early twentieth centuries are filled with doctors’ descriptions of individual patients with particular diseases — how the problem began, how it evolved in the patient, and what happened to the patient. The writer usually then speculated about what the particular case taught us about the malady. He would usually compare his findings to whatever previous authors had written about the disease.

We still use this technique today, although such case reports are very weak tools for deciding anything important about diseases. Any nonphysician can see the pitfalls in this sort of medical evidence. It is totally dependent upon what happens to turn up in the doctor’s individual practice, and there is no way to tell if a particular case is representative of all, or even most, instances of the disorder. It is merely an anecdote of one occurrence.

Slightly better than a case report is a collection of case reports, or case series. There is also a very long tradition of these in medical writing, and a very large series does tell us things that are increasingly likely to be true as the series gets larger. But there remains a huge problem in using case series to understand whatever the problem is: they are not a random sample of all cases; rather, they were selected in ways that easily introduce bias. For example, a particular doctor may become known as an expert in a particular disease and so people with the problem come to see him. Or perhaps only patients with more severe, unusual forms find their way to him because the milder varieties are cared for by someone else or are never seen by a doctor at all.

One can imagine a large number of other circumstances that would introduce bias into whatever the doctor writing the case series would see. These issues make case reports and case series only slightly better than expert opinion as a tool for understanding medical causation and treatment. These pitfalls well illustrate a common saying among medical scientists: “The plural of anecdote is not data.”

The difficulties with isolated case reports are not unique to medicine. Consider something like an internet message board, most of which are devoted to specific topics. People posting on the board share their experiences and opinions about many things, such as particular products that work or do not work. Vigorous debate often ensues, some of it supported by evidence of some kind, some of it not. But the effect is that of a series of case reports, and readers of the messages have no idea how representative is the experience of an individual poster.

Case reports and series are an example of what is called selection bias — the possibility, or even the probability, that the individual cases have not been selected randomly from the total group they come from, which is all people who have the disease. They are therefore not representative of the entire group, and using them to draw any conclusions about the whole group is suspect. Consider again the example of the internet message board. If thousands of posters complain about a particular product, the odds get progressively higher there is some problem with it. But people with a complaint are probably more likely to post than are those satisfied with the product, so there is built-in selection bias. Additionally, the sample will include only people with internet access and familiarity with message boards. Only a survey of everybody who bought the product, or a properly randomized sample of them, can answer the question.

One thing everyone agrees on is that our economy cannot sustain the amount of money we spend on healthcare. That was clear even before the Wall Street meltdown, and it’s even more true now. The United States spends 16% its gross domestic product (GDP) on healthcare, a figure half again that of the next highest spending country (Switzerland, at 11%). Most other European countries spend 9-10%. We also spend much more per capita than anybody else. (These figures are from 2003, but little has changed since then — if anything, it’s worse.)

Not only do we spend more than anybody else, but by many measures, as a society we get much less for our money. That is, in spite of our high healthcare bills, the United States does not compare well with other countries in many measures of health.

What’s to be done? How can we find ways to spend less on healthcare but get better value for our dollar? One answer is that much of the money we spend is on unproven or even worthless treatments. Many authorities advocate we establish an independent agency of some kind to evaluate which treatments work and which ones don’t. Britain already has such an agency, called the National Institute for Health and Clinical Excellence. The way it works is that patients and physicians are free to use a non-approved treatment, but insurance won’t pay for it. As you can read in the linked article, there are some vocal opponents to the agency, something probably inevitable. But in the words of its director: “We are not trying to be unkind or cruel. We are trying to look after everybody.”

Opponents of such a concept complain this represents rationing of health care, because inevitably it would mean that patients won’t get all they may want. This is true, but in fact we’re already rationing care; we just use a more insidious method. Anyway, what else are we to do? There is simply not enough money, especially now, to pay for everything. It’s time we recognize that. An independent evaluation agency of this sort would make the decision-making process transparent and fair.

Here is another post taken from my newest book, How to Talk to Your Child’s Doctor. This one concerns what I call the egotist.

Egotism is a common trait among doctors, although most of us keep it under adequate control when dealing with patients. Throughout this book, the ideal doctor-parent encounter has been described as a collaboration among equals, each of which brings expertise to the exchange; the doctor knows medicine, the parent knows the child. This is the ideal, although sometimes the reality falls short of it. The way our medical system is now structured gives more power and influence to the doctor side of the relationship than the patient side. As you read in chapter 7, things were not always this way; a century ago a surplus of doctors with treatments of doubtful usefulness scrambled to attract patients. These days, however, physicians have many more therapies that actually work, plus the benefit of an enormous medical establishment behind them. So now doctors are usually the ones deciding who gets what treatment. In spite of that fact, good, experienced doctors will do their best to use their power over patients lightly, always inviting parents and patients to share in the authority.

Physician egotism can get in the way of good communication in several ways. A simple manifestation is the tug-of-war over whose time is more valuable, the doctor’s or the parents’. A good example of this conflict is the doctor who schedules far more patient appointments than he can accommodate in a day, then seems unaware of how keeping a parent waiting for hours can poison the atmosphere even before the evaluation has even begun. Parents usually understand long waits when they take their child to the doctor for an unanticipated acute problem. If the waiting room is full of children just like theirs, there is little the doctor can do except see them each in turn. But the subspecialist who packs his waiting room with too many scheduled patients is proclaiming, in effect, that his time is far more valuable than that of parents, who often must take off a full day’s work to bring their child to see him.

The egotistical doctor is one who tends to forget that the patient is the center of everything, the reason the parents are there in the first place. He forgets that the encounter is about the child, not the doctor. This attitude can show itself in a persistent tendency to turn the subject of the conversation away from the child and toward the doctor. The result may be harmless, as when a garrulous doctor is genuinely trying to relax the parents and their child with a friendly conversation about other things, or it may be more toxic, as when a doctor constantly talks about himself and what he does. The latter can be particularly trying to parents who have waited a long time to see the doctor, only to find their brief time with him taken up by extraneous chatter.

Although it can be annoying to parents, excessive egotism in your child’s doctor is generally a minor issue in the big picture of getting your child the evaluation she needs. I say this because, although there are exceptions to everything, for the large majority of doctors I have met who are more egotistical than the average, their self-centeredness does not get in the way of their medical skills. In fact, some subspecialties, such as high-risk surgery, almost require the physician to have a huge ego if he is to perform such surgeries effectively .

So it is largely a matter of the personal taste of the parents. If you find yourself irritated when talking with an excessively egotistical doctor, and if you think this is interfering with his proper evaluation of your child, the best thing to do is to be persistent in turning the conversation back to your child at every opportunity. Of course, if you are really irritated by his manner or the way he treats you, do your best not to see him again.

Most doctors are paid by some version of how they have always been paid–what is loosely called “fee for service.” The notion is simple: the doctor gets paid for each encounter with a patient, whether this is an office visit or a major surgical operation. Thus the more the doctor does, the more he gets paid. It seems fair. After all, shouldn’t we get paid for the work we do?

The fee-for-service model, however, has long had critics. The most fundamental objection is that it rewards doctors for doing things. In an environment like that, one in which the more one does the more he gets paid, the doctor is tempted to do things that don’t need to be done, or choose the thing to do for which he gets paid more rather than the thing that pays less. In the ideal situation, of course, the doctor won’t consider those things–rather, he will put the patient’s best interests first. But doctors are human, and fee-for-service presents a doctor with a fundamental conflict of interest.

The alternative to fee-for-service is some sort of payment system in which the doctor is paid a salary that is the same no matter how much he does. This is currently done by some large practices, including the Mayo Clinic. Critics of this salaried system believe that, without financial incentives, doctors will simply not work as hard. Other physician groups blend together the two approaches, with a salary supplemented by some sort of bonus for doctors who do more.

The debate is more than a financial one–it is also a philosophical one. Most free market enthusiasts strongly support fee-for-service; those who favor tighter regulation of medical care, often including one of various single-payer models, are typically open to salary-based payment models. Salary-model systems also are frequently used by Health Maintenance Organization (HMO) systems.

Historically, organized medicine has been strongly opposed to paying physicians by any other method than fee-for-service. Seventy-five years ago, physicians who accepted salaried arrangements were ostracized by their peers and sometimes even penalized. This view has changed to some extent, but I think it is still fair to say that most American physicians favor traditional fee-for-service.

For myself, I favor a salary model (or salary plus a modest incentive for extra productivity) for what I do. I work in the field of intensive care, which lends itself well to this. Other specialties are somewhat different. My job, in effect, is to be like a firefighter waiting in the firehouse–if the PICU is busy, I work harder; if there are less patients, I can ease up. After all, we pay firefighters whether or not they are fighting a fire.

I see no reason why physician payment strategies must be all one thing or all another. It seems to me that whatever evolves from our current chaotic situation could find a place for both approaches. Hard work should be rewarded. However, and this is a big however, we need to understand the inherent conflict of interest of traditional fee-for-service medicine. Also, not all rewards for hard work need be financial ones.

This is another post about how non-physicians can understand how physicians use evidence. As I noted before, medical evidence has a hierarchy of reliability. The least reliable of these is expert opinion. This seems counter-intuitive: why is expert opinion the worst sort of evidence? Should not the experts know what they are talking about? In general, of course, experts do know what they are talking about — that is what makes them experts. But a closer examination of the matter shows why this kind of evidence is the weakest and most subjective; after all, it is one person’s opinion (or sometimes a committee of persons’ opinions), and opinions can be incorrect.

We need to look closely at just why a particular individual is considered an expert, and by whom. Credentials are important: where did the person obtain her training, where does she work now, and what is her standing among her peers? These seem obvious questions to ask, but these days an astonishing number of people with dubious or no credentials can write a book, put up a website, or start a blog, and, if they are persuasive marketers, can convince others they are experts. Fortunately for parents, the same wide-open quality of the internet allows one to search the background, credentials, and accomplishments of any putative expert. Wise parents will do this as a matter of course before deciding whether to take the expert’s advice on any important matter about their child’s health.

Experts who advise you to do one thing or another with your child typically base their advice to you on their own interpretation of the available medical research. They have the knowledge and training to understand the often esoteric medical literature. In addition, most experts themselves do research in the relevant field. Those are important and useful things. However, there are still good reasons why we should regard such opinions as the worst kind of data — better than nothing, but sometimes only barely so.

For one thing, the reason an expert holds a particular opinion may be because she was taught that way by her teachers, who may have, in turn, been taught the same thing by their teachers. Medicine is practical and empirical enough that such received, traditional opinions will not be tossed out unless they are consistently wrong. It is also true we physicians venerate our medical forebears to the extent that misguided opinions can occasionally persist long after they should have been discarded. So sometimes the answer to why doctors do something a particular way is that we have always done it that way.

Experts also form their opinions based upon what they have seen in the past. If their experience is long, often they have seen quite a few instances of whatever is under discussion, and that experience should count for something. On the other hand, memory is a tricky thing; sometimes we recall things in ways that can ultimately prove misleading. For example, the more striking and dramatic things tend to stay in our minds better than the more mundane things, and medical experts are not immune to this phenomenon. For example, I know that I remember unusual manifestations of certain cases for decades, and this inevitably colors how I approach the next child with that particular problem. Even though I know the case was unusual, I naturally think of its circumstances whenever I care for another child with whatever the disorder was. This is an example of what we call recall bias.

There are other kinds of bias that may affect the judgment of medical experts, and some of them are not innocent things like tricks of memory. Medical experts are no different from other kinds of experts, such as foreign policy pundits or stock market analysts, in that we, too, may have agendas that are not obvious to parents listening to our advice. Any controversial subject will lead to partisanship, and medical debates are no different. Parents considering the advice of medical experts should be alert to what a particular expert’s agenda might be. This is not necessarily a sinister thing; I think the great majority of experts advocating one position or another do so because they truly believe it is the correct one. But it is still a real thing.

Sometimes, however, medical experts may have agendas that are not so innocent. For example, there have been recent examples of experts touting one treatment over another when they have an undisclosed interest in the outcome. The conflict of interest could be intellectual, such as past friendships or associations with researchers of a particular treatment, or they could be crassly commercial. The ethical boundaries are, in theory, quite sharp, but there have been well-known examples of medical experts recommending a particular treatment when they have a financial conflict of interest regarding the outcome.

The best experts, of course, are the ones who tell you the basis of their opinions. They do not just pontificate about what is best for your child — they tell you how their reading of the best evidence led them to their informed opinion. They interpret for you the meaning of the scientific evidence. On the whole, most medical experts will do this for parents. Even so, it is a good thing for parents not to take whatever the experts say entirely on faith; it is better to have some grasp of how medical evidence is collected and analyzed. And besides, even experts can be wrong.