Evidence for Health

How do health practitioners know what to do for you? How do you know what to do for yourself?

Both health practitioners and you evaluate evidence, make decisions, and take actions—or not.

So it seems odd to say that the dominant mode of thought in health science is called evidence-based medicine. The phrase got traction two decades ago and was intended to discipline health practitioners into making decisions—and hence treating patients—based on the best available science. This would be in contrast to decisions using “professional judgment,” “intuition” and other unscientific practices.

The move to evidence-based medicine is an example of scientism and reflects an earlier move by the medical establishment at the beginning of the 20th Century that associated allopathic medicine with science and other health practices with ignorance and hucksterism—very successfully, I might add. Scientism is the idea that only knowledge that is the result of the scientific method is valid. This, of course, is nonsense—not least because what is counted as “the scientific method” is not the product of pure reason but innumerable social forces.

But first, let’s consider you and me and what we know about health and how we know it. There’s our direct experience and there’s what somebody told us. “Direct experience” includes what you learn by watching other people. “What somebody told you” comes in several varieties. One is information you get by chatting with other people. Then there’s what gets reported in your favorite information medium, typically by a journalist. Finally there’s what health experts tell you, whether person-to-person in the doctor’s office or, again, through your favorite information medium (again, typically by a journalist). None of these qualify as evidence-based.

What this illustrates is that the way you and I know what we know is through the social transmission of information. In other words, what we learn depends very much on social context and is thus very much affected by social forces. A recent piece of research discusses the effectiveness of story-telling in that process. The researcher is not on the faculty of a neuroscience or psychology or sociology department, but of a marketing department.

I want to draw your attention to evidence-based medicine as a story. That story tells us that health knowledge comes from science devoid of social context and therefore unaffected by social forces. After examining how evidence-based medicine is actually put into practice, one critic (from within conventional science itself) wrote an article titled “From Evidence-based Medicine to Marketing-based Medicine: Evidence from Internal Industry Documents.”

The cracks go even deeper. In evidence-based medicine, some evidence is better than others—this is the part about what counts as “the scientific method.” Randomized clinical trials are at the head of the class. Published in a prestigious medical journal, a recent article lists five basic flaws of clinical trials and goes on to discuss an alternative story for evaluating treatments. Even more deeply, other critics within conventional medicine argue that health practitioners not only don’t pour over the science but aren’t particularly competent to do so. So if health practitioners aren’t pouring over the science in devising treatments and even if they were pouring over it couldn’t really understand it, how are they figuring it all out?

Not long ago I read an article in the field of science translation: the practice of getting basic research into the hands of practitioners. To my utter surprise, it opened with a discussion of trust in research. “Trust” is a social phenomenon. In other words, health practitioners figure out what to do based on their trust in what others have told them.

Let’s go back to your and my health knowledge, now not looking so bad. Other people are exposing you to information all the time. Some of it makes sense, some of it doesn’t, and some of it you ponder. The outcome of your pondering (or even listening) depends on how much you trust the source. So you and health practitioners are not so far apart after all.

The problem is that health practitioners, by thinking of themselves as involved in evidence-based medicine, think their doing something they’re not—namely making decisions out of social context and unaffected by social forces. That they aren’t is demonstrated by ongoing projects such as the Dartmouth Atlas of Health Care, which shows wide variation in medical treatments based on geographical location. That is, depending on where you live, you might be at much greater risk of having a hysterectomy, for example, than elsewhere. This is clearly a social phenomenon, with patients and doctors and insurance companies playing parts in a particular story.

Isn’t the scientific method supposed to correct this? The operative words are “supposed to.” Although such self-correction is at the core of the scientific method in the abstract and although, as I’ve just reported, criticisms are out there, the actual practice of self-correction is extremely messy and often simply does not work.

Ten years ago, leading researchers at the Harvard School of Public Health published an article titled “Types of Dietary Fat and Risk of Coronary Heart Disease: A Critical Review.” These are researchers who had long produced studies contributing to the literature on the dangers of saturated fat and cholesterol. But the review article ten years ago essentially said that there was no good science to show that saturated fat and cholesterol are problems. And yet to this day you will find—in both mainstream and alternative media, in packaging and advertising, in the advice of health practitioners both conventional and alternative—dire warnings about the need to control saturated fat consumption and cholesterol. Very significant social forces are at work here, and these are not entirely or even mostly the result of marketing-based medicine.

Reformers hope to educate patients, practitioners, and journalists to better understand the science. They don’t seem to realize that this isn’t about science but about the politics of science. And that the moral of this story is “Be careful who you trust.”