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It seems as though it's not enough to just advocate for an improvement to medical practice. People want to entirely "re-brand" medicine instead. As though one facet of practice can define the whole. In the case of evidence-based medicine -- "EBM" -- the claim of the brand has always been a bit overblown.

Don't get me wrong: I'm enthusiastic about evidence, and think strong evidence is invaluable for medicine. But the EBM movement and brand - that's more complicated.

can be valuable. Like-minded people establishing organizations and forming loose communities can really spread ideas and influence. I always seem to be in one or another. There are risks, though, even when the core idea is beneficial. Movements develop self-interests. It's hard to keep them from drifting into collision with the public interest. The EBM movement hasn't avoided that.

In large part, it's because the EBM movement developed commercial interests, with academic interests entwined. There isn't anything inherently wrong with brands of evidence for sale, or academics wanting to be cited and be "key opinion leaders." But somewhere along the line, the principle of wanting people to use the best evidence lost ground to the temptation to push brands instead. And started to slip into just the kind of "eminence-based medicine" EBM sought to replace.

One of the successes of the EBM movement has been helping drive the popularization and growth of systematic reviews and meta-analysis. But I don't think we'll ever have enough up-to-date ones . And too often, social forces and personal bias drive uncritical acceptance of highly biased systematic reviews -- and criticism of anyone who disagrees with them.

Systematic reviews are . There are many ways that people can minimize biases during the research process. But there is still plenty of room for people to maneuver to a desired conclusion, too, if they are so minded. That we now have so many now coming to conflicting conclusions about the same bodies of evidence makes that clear. The resulting meta-analyses seem simple to digest and use, because so much is crunched down into a single summary statistic. Meta-analyses are complex, though, and hard to argue with effectively if you don't know a lot about them.

Once a systematic review confirms what people want to believe, social forces can take it from there. The conclusions can become cause celebres even if the evidence base is weak or the review's methods are intransparent or disputable. I think that happened with debriefing to prevent and , for example.

One of the underlying issues contributing to this is that "EBM" is particularly compatible with some other ideological positions, such as being especially or anti-industry. That makes the movement very attractive to people with a barrow to push. Keeping the patient and public interest central requires real effort. While it's easy to think that another ideology is consistent with that, when it gets to a point where it's not, that can be hard to detect.

Another underlying issue is typical of many social movements -- and proponents of most things in medicine, come to that. And that's the self-fulfilling prophecy that comes of believing in the inherent value of something so strongly, that you are not vigilantly assessing its unintended adverse effects. That's something I've long .

Although the movement has always been self-critical about its scientific methods, ironically, it's taken an anecdotal approach to itself. It has focused on stories about its successes, the harms caused when others did not follow an EBM approach, or why evidence isn't acted on -- but without an equal concern for evidence-based mistakes or movement-driven harm.

Things might be changing on that front, though. Recently, there was a very public clash in the BMJ between leading figures of the Cochrane Collaboration -- all acting in a personal capacity. One, Peter Gotzsche, has an anti-industry, anti-intervention agenda across multiple topics, often in conflict with other individuals (disclosure: including me). This time, though, a Gotzsche opinion piece arguing met with a strong rebuttal from three other leaders, including Cochrane's editor-in-chief David Tovey. That's a good sign -- and, perhaps, a turning point. If "EBM" begins to be more critical and proactive about the biases within it, and not just those of others, medicine will be the better for it.

The cartoon in this post is my own (): more at .

Hilda Bastian is a senior clinical research scientist. She works at the National Institutes of Health as editor for the clinical effectiveness resource and as editor for PubMed Commons, PubMed's scientific publication commenting system. She is an academic editor at PLOS Medicine, and blogs for PLOS (Absolutely Maybe) as well as on a personal cartoon clinical epidemiology blog (Statistically Funny). The thoughts Hilda Bastian expresses here at Third Opinion are personal, and do not necessarily reflect the views of the National Institutes of Health or the U.S. Department of Health and Human Services.

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