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Posts Tagged EBM

The Forerunners of EBM

The term “evidence-based medicine” first appeared in the medical literature in 1992. It quickly became popular and developed into a systematic enterprise. A book by Ulrich Tröhler To Improve the Evidence of Medicine: The 18th century British origins of a critical approach argues that its roots go back to the 1700s in Scotland and England. An e-mail correspondent recommended it to me. Can’t remember who, but I would like to thank him.

Francis Bacon (1561-1626) differentiated between “ordinary experience” (chance observations) and more objective “ordered experience” (methodological observations). Both of these involved empirical knowledge.  It’s hard to get back into the mindset of his time, when most physicians rejected empiricism as the sphere of quacks and surgeons.  Tröhler helps us understand why they did:

…since antiquity, the mark of distinction of a learned man had been the certainty of his knowledge. A doctor knew — he did not need to test his kind of knowledge empirically because this would imply acknowledgement of uncertainty.

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Posted in: Book & movie reviews, History

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“How do you feel about Evidence-Based Medicine?”

That was the question asked on a Medscape Connect discussion

I did a double-take. How do you feel? Could anybody object to the idea of basing treatments on evidence? The doctor who started the discussion asked:

Besides using EBM, a lot of my prescribing comes from anecdotal experience and intuition. How about you? Where do you get your information from that you use to treat your patients? Do you always ascribe to EBM, or do you deviate from it with certain medical conditions/patients?

I had naively thought that my profession uniformly embraced EBM. How could they not? The commenters broke my bubble big-time. Some of them summarily reject EBM… although it appears that what they are rejecting is not what I understand EBM to mean. (more…)

Posted in: Science and Medicine

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CAM and Evidenced-Based Medicine

Mark Tonelli, MD has problems with evidence-based medicine (EBM). He has published a few articles detailing his issues, and he makes some legitimate points. We at science-based medicine (SBM) have a few issues with the execution of EBM as well, so I am sympathetic to constructive criticism.

In an article titled: Integrating evidence into clinical practice: an alternative to evidence-based approaches. The abstract states:

Evidence-based medicine (EBM) has thus far failed to adequately account for the appropriate incorporation of other potential warrants for medical decision making into clinical practice. In particular, EBM has struggled with the value and integration of other kinds of medical knowledge, such as those derived from clinical experience or based on pathophysiologic rationale. The general priority given to empirical evidence derived from clinical research in all EBM approaches is not epistemically tenable. A casuistic alternative to EBM approaches recognizes that five distinct topics, 1) empirical evidence, 2) experiential evidence, 3) pathophysiologic rationale, 4) patient goals and values, and 5) system features are potentially relevant to any clinical decision. No single topic has a general priority over any other and the relative importance of a topic will depend upon the circumstances of the particular case. The skilled clinician must weigh these potentially conflicting evidentiary and non-evidentiary warrants for action, employing both practical and theoretical reasoning, in order to arrive at the best choice for an individual patient.

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Posted in: Science and Medicine

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Of SBM and EBM Redux. Part IV, Continued: More Cochrane and a little Bayes

OK, I admit that I pulled a fast one. I never finished the last post as promised, so here it is.

Cochrane Continued

In the last post I alluded to the 2006 Cochrane Laetrile review, the conclusion of which was:

This systematic review has clearly identified the need for randomised or controlled clinical trials assessing the effectiveness of Laetrile or amygdalin for cancer treatment.

I’d previously asserted that this conclusion “stand[s] the rationale for RCTs on its head,” because a rigorous, disconfirming case series had long ago put the matter to rest. Later I reported that Edzard Ernst, one of the Cochrane authors, had changed his mind, writing, “Would I argue for more Laetrile studies? NO.” That in itself is a reason for optimism, but Dr. Ernst is such an exception among “CAM” researchers that it almost seemed not to count.

Until recently, however, I’d only seen the abstract of the Cochrane Laetrile review. Now I’ve read the entire review, and there’s a very pleasant surprise in it (Professor Simon, take notice). In a section labeled “Feedback” is this letter from another Cochrane reviewer, which was apparently added in August of 2006, well before I voiced my own objections:

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Posted in: Clinical Trials, Homeopathy, Medical Academia, Science and Medicine

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Of SBM and EBM Redux. Part III: Parapsychology is the Role Model for “CAM” Research

This is the third post in this series*; please see Part II for a review. Part II offered several arguments against the assertion that it is a good idea to perform efficacy trials of medical claims that have been refuted by basic science or by other, pre-trial evidence. This post will add to those arguments, continuing to identify the inadequacies of the tools of Evidence-Based Medicine (EBM) as applied to such claims.

Prof. Simon Replies

Prior to the posting of Part II, statistician Steve Simon, whose views had been the impetus for this series, posted another article on his blog, responding to Part I of this series. He agreed with some of what both Dr. Gorski and I had written:

The blog post by Dr. Atwood points out a critical distinction between “biologically implausible” and “no known mechanism of action” and I must concede this point. There are certain therapies in CAM that take the claim of biological plausibility to an extreme. It’s not as if those therapies are just implausible. It is that those therapies must posit a mechanism that “would necessarily violate scientific principles that rest on far more solid ground than any number of equivocal, bias-and-error-prone clinical trials could hope to overturn.” Examples of such therapies are homeopathy, energy medicine, chiropractic subluxations, craniosacral rhythms, and coffee enemas.

The Science Based Medicine site would argue that randomized trials for these therapies are never justified. And it bothers Dr. Atwood when a systematic review from the Cochrane Collaboration states that no conclusions can be drawn about homeopathy as a treatment for asthma because of a lack of evidence from well conducted clinical trials. There’s plenty of evidence from basic physics and chemistry that can allow you to draw strong conclusions about whether homeopathy is an effective treatment for asthma. So the Cochrane Collaboration is ignoring this evidence, and worse still, is implicitly (and sometimes explicitly) calling for more research in this area.

On the other hand:

There are a host of issues worth discussing here, but let me limit myself for now to one very basic issue. Is any research justified for a therapy like homeopathy when basic physics and chemistry will provide more than enough evidence by itself to suggest that such research is futile(?) Worse still, the randomized trial is subject to numerous biases that can lead to erroneous conclusions.

I disagree for a variety of reasons.

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Posted in: Acupuncture, Clinical Trials, Energy Medicine, Faith Healing & Spirituality, Herbs & Supplements, Homeopathy, Medical Academia, Medical Ethics, Science and Medicine

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Evidence-Based Medicine, Human Studies Ethics, and the ‘Gonzalez Regimen’: a Disappointing Editorial in the Journal of Clinical Oncology Part 1

Background: the distinction between EBM and SBM

An important theme on the Science-Based Medicine blog, and the very reason for its name, has been its emphasis on examining all the evidence—not merely the results of clinical trials—for various claims, particularly for those that are implausible. We’ve discussed the distinction between Science-Based Medicine (SBM) and the more limited Evidence-Based Medicine (EBM) several times, for example here (I began my own discussion here and added a bit of formality here, here, and here). Let me summarize by quoting John Ioannidis:

…the probability that a research finding is indeed true depends on the prior probability of it being true (before doing the study), the statistical power of the study, and the level of statistical significance.

EBM, in a nutshell, ignores prior probability† (unless there is no other available evidence) and falls for the “p-value fallacy”; SBM does not. Please don’t bicker about this if you haven’t read the links above and some of their own references, particularly the EBM Levels of Evidence scheme and two articles by Steven Goodman (here and here). Also, note that it is not necessary to agree with Ioannidis that “most published research findings are false” to agree with his assertion, quoted above, about what determines the probability that a research finding is true.

The distinction between SBM and EBM has important implications for medical practice ethics, research ethics, human subject protections, allocation of scarce resources, epistemology in health care, public perceptions of medical knowledge and of the health professions, and more. EBM, as practiced in the 20 years of its formal existence, is poorly equipped to evaluate implausible claims because it fails to acknowledge that even if scientific plausibility is not sufficient to establish the validity of a new treatment, it is necessary for doing so.

Thus, in their recent foray into applying the tools of EBM to implausible health claims, government and academic investigators have made at least two, serious mistakes: first, they have subjected unwary subjects to dangerous but unnecessary trials in a quest for “evidence,” failing to realize that definitive evidence already exists; second, they have been largely incapable of pronouncing ineffective methods ineffective. At best, even after conducting predictably disconfirming trials of vanishingly unlikely claims, they have declared such methods merely “unproven,” almost always urging “further research.” That may be the proper EBM response, but it is a far cry from the reality. As I opined a couple of years ago, the founders of the EBM movement apparently “never saw ‘CAM’ coming.”

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Posted in: Cancer, Clinical Trials, Medical Academia, Medical Ethics, Politics and Regulation, Science and Medicine

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Medicine’s Beautiful Idea

For most of human history, doctors have killed their patients more often than they have saved them. An excellent new book, Taking the Medicine: A Short History of Medicine’s Beautiful Idea, and Our Difficulty Swallowing It, by Druin Burch, MD, describes medicine’s bleak past, how better ways of thinking led to modern successes, and how failure to adopt those better ways of thinking continues to impede medical progress.

The moral is not that doctors once did foolish things. The moral is that even the best of people let themselves down when they rely on untested theories and that these failures kill people and stain history. Bleeding and mercury have gone out of fashion, untested certainties and overconfidence have not.

Burch’s conversation with his rowing coach epitomizes the problem:

“I want you to keep your heart rate at 85% of max for the next hour and a half.”
“Why?”
“Because it’s the best way to improve your fitness.”
“How do you know?”
“Because I’ve done it before and it worked. Because that’s what the people who win the Olympics do. I know, I’ve trained some of them.”
“But has anyone actually done an experiment?”
“What on earth are you talking about?”

This book is Burch’s answer to his coach’s question. Medicine’s “beautiful idea” is that we should test all hypotheses and beliefs using the kind of tests that are reliable for determining the truth. Instead of going by tradition, authority, theory, common sense, or personal experience, we now have effective tools to find out for sure whether a treatment really works. (more…)

Posted in: Book & movie reviews, History, Science and Medicine

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When Further Research Is NOT Warranted: The “Wisdom of Crowds” Fallacy

Most scientific research studies have at least one thing in common: the conclusion section ends with, “further research is warranted.” I’d say it’s about as common as the “talk to your doctor” disclaimer in TV ads for pharmaceutical products. And in a way, they both serve the same purpose. They’re a “CYA” move.

What does “further research is warranted” mean in plain English? I think it can be roughly translated: “My research study is not of the size or scope to fully explain all the phenomena described in this article. Therefore, draw conclusions beyond the data and study methods at your own risk. And yeah, my work is important and cool – so people should study it further.”

Of course, the first two sentences are reasonable – we should always remember not to draw conclusions beyond the information provided by the data we’ve collected (even though that’s about as challenging as getting a beagle not to eat a table scrap in an empty room). The real problem is the third sentence. Is the research promising enough to require further investment? How are we to know if further research is indeed warranted? I would argue that it should not be based solely on the subjective opinions of the researchers nor the popularity of the research topic to the general public. (more…)

Posted in: Clinical Trials, General, Science and Medicine

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