StATS: Postmodern thought and evidence based medicine (September 7, 2006)
A recently published article:
has been drawing a lot of attention on the Internet. It takes a post-modern look at Evidence Based Medicine and in the abstract they report that
the evidence-based movement in the health sciences is outrageously exclusionary and dangerously normative with regards to scientific knowledge. As such, we assert that the evidence-based movement in health sciences constitutes a good example of microfascism at play in the contemporary scientific arena.
A lot has been written in this list about postmodern philosophy both pro and con and it is hard to sort out the claims and counterclaims.
A careful definition of post-modernism is hard to find, and many people define it in a way that it represents everything that is good, and others define in a way so that it represents everything that is bad. I like the Wikipedia for its efforts to present controversial topics from a neutral point of view (an effort that some post modern thinkers would argue is not possible). The web page on postmodernism:
offers a range of definitions, three of which I believe are relevant to EBM. First postmodernism is
A continual skepticism towards the ideas and ideals of the modern era, especially the ideas of progress, objectivity, reason, certainty & personal identity, and grand narrative in general
This definition places postmodernism in conflict with EBM, which often cites examples of medical progress through the careful application of medical research. For example, we have learned that folate supplementation during pregnancy reduces the risk of neural tube defects through the use of several randomized trials.
Postmodernism and EBM also conflict over the concept of objectivity. EBM promotes objectivity through the use of grading scales, user guides to the literature, systematic overviews, and so forth.
Two other definitions on the Wikipedia page represent skepticism about objectivity.
Postmodernism can be defined as
The belief that all communication is shaped by cultural bias, myth, metaphor, and political content.
The assertion that meaning and experience can only be created by the individual, and cannot be made objective by an author or narrator.
Perhaps the most popular exposition of a postmodern philosophy is the claim in Dan Brown's DaVinci Code that "history is written by the winners." It is actually through an analogy of historical thought that the concept of postmodernism became clearer to me.
Can historians reach an objective conclusion about something like the existence of the Holocaust? That's a topic tackled early in a book by Michael Shermer and Alex Grobman, "Denying History: Who Says the Holocaust Never Happened and Why Do They Say It?" The book reviews the evolution of historical thought which started as a belief that an objective account of history was an achievable goal. It then evolved into a postmodern belief that all historical accounts reflect the viewpoint of the historian. Note the quote on the Wikipedia page on history
In recent years, postmodernists have challenged the validity and need for the study of history on the basis that all history is based on the personal interpretation of sources. en.wikipedia.org/wiki/History
The most recent perspective on history, according to Shermer and Grobman, is that personal interpretations do influence historical accounts to some extent and some historical facts will always remain in dispute. But historians can indeed arrive at objective conclusions.
We prove the Holocaust through a convergence of data that include:
- Written documents-letters, memos, blueprints of the camps, orders, bills, speeches, articles, memoirs and confessions.
- Eyewitness testimony accounts from survivors, members of the Jewish sonderkomandos who took bodies out of the gas chambers, SS guards, commandants, local townspeople and high-ranking nazi officials. We have many letters from German soldiers stationed on the Russian front to their families in, which they describe the mass shooting of Jews.
- Photographs-including official military and press photographs, civilian photographs, secret photographs taken by survivors, aerial photographs, German and allied film footage and photographs taken by the German military.
- The camps themselves;
- And inferential evidence-population demographic, reconstructed from pre-World War II. For example, if six million were not killed, what happened to all these people?
(as quoted in www.holocaust-trc.org/deny_history.htm).
The Shermer and Grobman argument shows the folly of a total embrace of postmodern thought. If you believe that there is no possibility of an objective account of history, then you have to accept the possibility that the Holocaust was a creation of a Jewish conspiracy. So a total embrace of postmodern philosophy would leave us open to any crackpot theory that might come along.
On the other hand, a wholesale rejection of postmodern philosophy would lead to problems as well. When journal editors require disclaimers about financial conflicts of interest, it is done with the understanding that readers will interpret the data differently when they realize the source of the data. That sounds kind of postmodern to me.
Joel Best, in his book, Damned Lies and Statistics, has a very nice argument for postmodernism when he states:
"We sometimes talk about statistics as though they are facts that simply exist, like rocks, completely independent of people, and that people gather statistics much as rock collectors pick up stones. This is wrong. All statistics are created through people's action: people have to decide what to count and how to count it, people have to do the counting, and people have to interpret the resulting statistics, to decide what the numbers mean. All statistics are social products, the results of people's efforts."
This is not to say that all statistics are bad, just that you can't interpret them without first understanding the context in which they were created.
The same can be argued about EBM. Medical research is produced in a social context, and failure to recognize this is a serious limitation of EBM. Not to pick on a single medical specialty, but when someone argues "they're only saying this because they're surgeons" that is probably a good thing as long as you don't take it to the point of "you can't trust anything that a surgeon tells you."
I suspect (but have to admit that this is just speculation) that the authors of "Deconstructing the evidence-based discourse in health sciences: truth, power and fascism" have adopted a postmodern position because they are upset at the EBM rejection of some forms of alternative medicine. Indeed there are some in the alternative medicine community who adopt an evidentiary perspective that places individual patient narratives above randomized trials. Many alternative medicine websites offer wholesale criticisms of the medical research enterprise and offer anecdotal evidence in its place.
This antipathy is reflected from the opposite perspective by the comments of Angell and Kassirer in a famous NEJM editorial
There cannot be two kinds of medicine - conventional and alternative. There is only medicine that has been adequately tested and medicine that has not, medicine that works and medicine that may or may not work. Once a treatment has been tested rigorously, it no longer matters whether it was considered alternative at the outset. If it is found to be reasonably safe and effective, it will be accepted. Angell M, Kassirer JP, Alternative medicine--the risks of untested and unregulated remedies. N Engl J Med 1998;339:839.
There are, however, just as many proponents of alternative medicine who have embraced EBM and believe that when the proper research studies are done, they will support alternative medicine as superior to traditional Western medicine. There are also advocates of EBM who admit that the randomized control trial is not the ideal arbitrator of truth when evaluating alternative medicine.
- Mason S, Tovey P, Long AF. Evaluating complementary medicine: methodological challenges of randomised controlled trials. BMJ. 2002 Oct 12;325(7368):832-4.
So a bit of postmodernism is probably good medicine, as long as you don't overdose on it.
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