Plausibility bias? You say that as though that were a bad thing!

On Friday, you might have noticed that Mark Crislip hinted at a foreshadowing of a blog post to come. This is that blog post. He knew it was coming because when I saw the article that inspired it, I sent an e-mail to my fellow bloggers marking out my territory like a dog peeing on every tree or protecting my newfound topic like a mother bear protecting her cubs. In other words, I was telling them all to back off. This article is mine.

Mine! Mine! Mine! I tell you!

My extreme territorial tendencies (even towards my friends and colleagues) notwithstanding on this issue aside, if you read Mark’s post (and if you didn’t go back and read it now—seriously, go now), you might also remember that he was discussing a “reality bias” in science-based medicine (SBM), a bias that we like to call prior plausibility. In brief, positive randomized clinical trials (RCTs) testing highly implausible treatments are far more likely to be false positives than RCTs testing more plausible treatments. That is the lesson that John Ioannidis has taught us and that I’ve written about multiple times before, as have other SBM bloggers, most prominently Kimball Atwood, although nearly all of us have chimed in at one time or another about this issue.

Apparently a homeopath disagrees and expressed his disagreement in an article published last week online in Medicine, Health Care, and Philosophy entitled Plausibility and evidence: the case of homeopathy. You’ll get an idea of what it is that affected us at SBM like the proverbial matador waving his cape in front of a bull by reading this brief passage from the abstract:

Prior disbelief in homeopathy is rooted in the perceived implausibility of any conceivable mechanism of action. Using the ‘crossword analogy’, we demonstrate that plausibility bias impedes assessment of the clinical evidence. Sweeping statements about the scientific impossibility of homeopathy are themselves unscientific: scientific statements must be precise and testable.

Scientific. You keep using that word. I do not think it means what you think it means. Of course, his being a homeopath is about as close to a guarantee as I can think of that a person doesn’t have the first clue what is and is not scientific. If he did, he wouldn’t be a homeopath. Still, this particular line of attack is often effective, whether yielded by a homeopath or other CAM apologist. After all, why not test these therapies in human beings and see if they work? What’s wrong with that? Isn’t it “close-minded” to claim that scientific considerations of prior plausibility consign homeopathy to the eternal dustbin of pseudoscience?

Not at all. There’s a difference between being open-minded and being so “open-minded” that your brains threaten to fall out. Guess which category homeopaths like Rutten fall into. But to hear them tell it, homeopathy is rejected because because we scientists have a “negative plausibility bias” towards it. At least, that’s what Rutten and some other homeopaths have been trying to convince us. This article seems to be an attempt to put some meat on the bones of their initial trial balloon of this argument published last summer, which Steve Novella duly deconstructed.

Before I dig in, however, I think it’s necessary for me to “confess” my bias and why I think it should be your bias too.

Posted in: Basic Science, Clinical Trials, Homeopathy, Science and Medicine

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Stop Making Sense

I usually rely on the Secret.  Every two weeks or so the Universe offers up some bit of wacky whimsey and I have a topic for an SBM blog entry.  This week the Universe has failed me. Nothing has crossed my LCD so I have no studies to evaluate and I have been unusually busy at work preventing my browsing the Interwebs for material.  But try telling that to the Managing Editor.   I write half to amuse myself, half to learn about the topic, and half to clarify in my own mind the topics at hand (1).  So this week  is content free idle thoughts for my own benefit.

I have been reading 13 Things That Don’t Make Sense by Michael Brooks. The book concerns topics in science that are unexplained by the current understanding  of the laws of the universe or contradict the dominant paradigm. Well, almost.  His final topic is homeopathy, and it is the one topic whose conclusions, while qualified, belong on Failblog.  The first chapter concerns dark matter and dark energy and how what we can see makes up only a small fraction of the content of the universe.   (more…)

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

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The CAM Docket: Texas MDs v. DCs

In April, the Texas District Court of Appeals (Third District) affirmed a lower court ruling that chiropractors are prohibited from performing manipulation under anesthesia and needle electromyography[EMG]. The lower court also ruled that the Texas Board of Chiropractic Examiners exceeded its authority in defining the chiropractic scope of practice to include “diagnosis.” This part of the ruling was overturned by the Court of Appeals, but with some interesting language in the opinion which could turn their one win into a Pyrrhic victory for Texas chiropractors.  In a separate ruling, not on appeal, a lower court held that vestibular testing is outside the scope of chiropractic practice.

First, some background. Back in 1949, the Texas Legislature defined the scope of chiropractic practice as, among other things, “the practice of adjusting the vertebrae to correct any subluxation or misalignment thereof . . .” Over the ensuing years, the legislature amended the chiropractic practice act with an eye toward modernization, resulting in the current scope of practice being “nonsurgical, nonincisive procedures, including, but not limited to, adjustment and manipulation, in order to improve the subluxation complex or the biomechanics of the musculoskeletal system.” Now that’s progress!


Posted in: Chiropractic, Legal, Politics and Regulation

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Funding CAM Research

Paul Offit has published a thoughtful essay in the most recent Journal of the American Medical Association (JAMA) in which he argues against funding research into complementary and alternative therapies (CAM). Offit is a leading critic of the anti-vaccine movement and has written popular books discrediting many of their claims, such as disproved claim for a connection between some vaccines or ingredients and risk of developing autism. In his article he mirrors points we have made here at SBM many times in the past.

Offit makes several salient points – the first being that the track record of research into CAM, mostly funded by the NCCAM, is pretty dismal.

“NCCAM officials have spent $375,000 to find that inhaling lemon and lavender scents does not promote wound healing; $750,000 to find that prayer does not cure AIDS or hasten recovery from breast-reconstruction surgery; $390,000 to find that ancient Indian remedies do not control type 2 diabetes; $700,000 to find that magnets do not treat arthritis, carpal tunnel syndrome, or migraine headaches; and $406,000 to find that coffee enemas do not cure pancreatic cancer.”

The reason for the poor track record is fairly simple to identify – by definition CAM includes treatments that are scientifically implausible, which means there is a low prior probability that they will work. If the treatments were scientifically plausible then they wouldn’t be alternative.


Posted in: Clinical Trials, Herbs & Supplements, Medical Ethics, Politics and Regulation, Science and Medicine

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G-Spot Discovered? Not So Fast!

Is this the G-Spot?

The press release proclaims “Study Confirms Anatomic Existence of G-Spot.” The study itself is titled “G-Spot Anatomy: A New Discovery.”  It was just published in The Journal of Sexual Medicine.  The author, Adam Ostrzenski, is an “internationally renowned gynecologic surgeon” with multiple degrees (MD, PhD, Dr Hab) and many peer-reviewed articles listed in PubMed.

The G-spot, or Gräfenberg Spot, is an area on the anterior wall of the vagina that can be stimulated to produce sexual excitement, stronger orgasms, and maybe even female ejaculation. Its existence is questionable. Wikpedia has an extensive article explaining the controversy and the published evidence, pro and con, with links to the original sources. You can read more than you ever wanted to know about it there, so I won’t bother trying to repeat it here. A 2012 review of the G-spot literature concluded:  

Objective measures have failed to provide strong and consistent evidence for the existence of an anatomical site that could be related to the famed G-spot. However, reliable reports and anecdotal testimonials of the existence of a highly sensitive area in the distal anterior vaginal wall raise the question of whether enough investigative modalities have been implemented in the search of the G-spot.

Dr. Ostrzenski claims to have found the G-spot and taken its picture (above). Believers in Bigfoot and the Loch Ness monster have pictures too. They even had “Bigfoot hair” that later turned out to be synthetic wig fibers. Ostrzenski’s “proof” is no more credible than theirs.


Posted in: Basic Science, Obstetrics & gynecology

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Supplements and cancer prevention

The bloggers here have been very critical of a law passed nearly 20 years ago, commonly referred to as the DSHEA of 1994. The abbreviation DSHEA stands for about as Orwellian a name for a law as I can imagine: the Dietary Supplement Health and Education Act. Of course, as we’ve pointed out time and time again, the DSHEA is not about health, and it’s certainly not about education. Indeed, perhaps my favorite description of this law comes from our very own Peter Lipson, who refers to it as a “travesty of a mockery of a sham.” Rather, it’s about allowing supplement manufacturers and promoters of so-called “complementary and alternative medicine” (CAM, with or without a preceding “s,” depending on your taste) who do not want pesky things like government laws and regulations to interfere with their selling of pseudoscience to market various compounds as “dietary supplements” with near-impunity. As Harriet Hall put it so accurately, the DSHEA is “a stealth weapon that allows the sale of unproven medicines just as long as you pretend they are not medicines.”

The DSHEA accomplishes this by making a seemingly reasonable distinction between food and medicine and twisting it in such a way that allows manufacturers to label all sorts of botanicals and various other compounds, many of which have substances in them with pharmacological activity, and sell them as “supplements” without prior approval by the FDA before marketing. As long as the manufacturer is careful enough not to make health claims that are too specific, namely that the supplement can diagnose or treat any specific disease, and sticks to “structure-function” statements (“it boosts the immune system!”), almost anything goes, particularly if a Quack Miranda Warning is included.

Not surprisingly, given what a big business supplements have become in this country largely due to the DSHEA, manufacturers and CAM advocates fight tooth and nail against any attempt to update the DSHEA to correct some of its more unfortunate consequences. Led by Utah Senator Orrin Hatch and Iowa Senator Tom Harkin, who together make up a bipartisan tag-team in defense of the supplement industry and do their best to block any effort to increase its regulation by the FDA. We saw that most recently when Arizona Senator John McCain, of all people, introduced a bill in 2010 to try to tighten up the DSHEA and was thoroughly slapped down by Orrin Hatch. More recently, not satisfied with how good things are for the supplement industry, another Utah Representative Jason Chaffetz reached across the aisle to Jared Polis, teaming up to introduce the Free Speech About Science Act, which basically seeks to allow the supplement industry to make more liberal claims about its products. All it will need is a “peer-reviewed” paper to support it (Mark and David Geier would do!), and you can claim almost anything. Anything to grow the supplement industry, which is currently around $30 billion a year.

That’s why it’s critical, from time to time, to look at actual evidence, and just last week Maria Elena Martinez, PhD, of the University of California San Diego, and co-authors did in a commentary published online in the Journal of the National Cancer Institute entitled Dietary Supplements and Cancer Prevention: Balancing Potential Benefits Against Proven Harms.

Posted in: Cancer, Herbs & Supplements, Politics and Regulation

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Consumer Reports and Alternative Therapies

Consumer Reports (CR) and its Health Newsletter provide sound advice about nutrition and medicine, with one exception: their recommendations concerning alternative therapies, especially dietary supplements. With regard to dietary supplements, part of the problem is the failure of CR to make a distinction between authentic dietary supplements, such as multivitamins and minerals, and non-vitamin, non-mineral medicinal products. For example, the September 2010 issue of CR contains a table listing “Eleven supplements to consider”. The list includes calcium and vitamin D supplements, and St. John’s wort and Pygeum herbals.

The nomenclatural confusion was created by the Dietary Supplement Health and Education Act of 1994 (DSHEA), which was termed “The Snake Oil Protection Act” by the New York Times. DSHEA, which was passed after a massive lobbying campaign by industry, arbitrarily designated herbals and other traditional medicinal products as dietary supplements. Herbals are used worldwide as medicines and in Europe some are available by prescription only.

The purpose of the Act was to prevent the Food and Drug Administration (FDA) from effectively regulating those products, and it succeeded brilliantly. Sales of dietary supplements rose from $4 billion annually in 1994 to $28 billion in 2007, and reports of severe adverse events caused by those products rose in parallel (1). Another consequence of DSHEA is that designating herbals as dietary supplements misleads consumers about their medicinal nature and conceals their potential for causing severe adverse effects.

The selling points for herbals are that as “natural” products they are safer and gentler than the powerful “foreign” chemicals in purified medications, and they possess unique qualities not found in conventional medications. Dr. Varro Tyler, an expert in the medicinal use of plants, termed those unfounded claims “paraherbalism”, and described herbals as “crude drugs of vegetable origin” (2). In reality, the active ingredients of plants are chemicals that are similar or identical to conventional medications, and many of the latter were first identified in plant extracts. It is no more “natural” to swallow dozens of chemicals in a plant extract than to ingest a single purified chemical – a drug is a drug. Before discussing CR’s advice about supplements, it is necessary to consider briefly basic differences between herbals and conventional medications.


Posted in: Herbs & Supplements, Legal, Science and the Media

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Gold mine or dumpster dive? A closer look at adverse event reports

All informed health decisions are based on an evaluation of expected risks and known benefits. Nothing is without risk. Drugs can provide an enormous benefit, but they all have the potential to harm. Whether it’s to guide therapy choices or to ensure patients are aware of the risks of their prescription drugs, I spend a lot of time discussing the potential negative consequences of treatments. It’s part of my dialogue with consumers: You cannot have an effect without the possibility of an adverse effect. And even when used in a science-based way, there is always the possibility of a drug causing either predictable or idiosyncratic harm.

An “adverse event” is an undesirable outcome related to the provision of healthcare. It may be a natural consequence of the underlying illness, or it could be related to a treatment provided. The use of the term “event” is deliberate, as it does not imply a cause: it is simply associated with an intervention. The term “adverse reaction,” or more specifically “adverse drug reaction,” is used where a causal relationship is strongly suspected. Not all adverse events can be be causally linked to health interventions. Consequently, many adverse events associated with drug treatments can only be considered “suspected” adverse drug reactions until more information emerges to suggest the relationship is likely to be true.

Correlation fallacies can be hard to identify, even for health professionals. You take a drug (or, say, are given a vaccine). Soon after, some event occurs. Was the event caused by the treatment? It’s one of the most common questions I receive: “Does drug ‘X’ cause reaction ‘Y’?” We know correlation doesn’t equal causation. But we can do better than dismissing the relationship as anecdotal, as it could be real. Consider an adverse event that is a believed to be related to drug therapy: (more…)

Posted in: Epidemiology, Pharmaceuticals

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Hypnotherapy For Pain and Other Conditions

Hypnotherapy is the use of hypnosis as a medical intervention, usually for the treatment of pain and other subjective symptoms. It remains controversial, primarily because the evidence for its efficacy is not yet compelling, but also because it is poorly understood. This situation is not helped by the fact that it is often characterized as an “alternative” therapy, a label that can “ghettoize” an otherwise legitimate treatment modality.

What Is Hypnosis?

Any meaningful discussion of hypnosis, or any other phenomenon, needs to start with a specific, and hopefully operational, definition.  If we cannot define hypnosis then it becomes impossible to meaningfully discuss it. The problem of definition plagues the science dealing with many so-called alternative therapies, such as acupuncture.  Good science requires controlling for specific variables, so that we can determine which variables are having what effects. If we don’t know which variables are part of the operational definition of a specific therapy, then we cannot conduct proper studies or interpret their results.

For example, with acupuncture, in my opinion the only meaningful definition of this procedure is the placing of thin needles into specific acupuncture points in order to elicit a specific response. Research has shown, however, that acupuncture points do not exist, that placing needles at specific points is not associated with a specific outcome, and even that sticking needles through the skin (as opposed to just poking the skin superficially) does not correlate with outcome. When these variables are isolated they do not appear to contribute anything to efficacy, therefore one might conclude that acupuncture does not work. Research into acupuncture, however, often does not adequately isolate these variables from the therapeutic ritual that surrounds acupuncture, or even mixes in other modalities, such as electrical stimulation.


Posted in: Neuroscience/Mental Health

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Chiropractors as Family Doctors? No Way!

A recent three-part article published in ACA News advocates turning chiropractors into “conservative primary care providers” who would be the initial point of contact for patients, would serve as gatekeepers for referrals to medical doctors and specialists, and would co-manage patients with those specialists on a continuing basis: essentially, family doctors.  I think that’s a terrible idea. It might benefit chiropractors by increasing their market share, but it wouldn’t benefit patients. There is no evidence to indicate that chiropractors are capable of filling that role effectively or safely.

NUHS. The article was co-authored by several chiropractors on the faculty of the National University of Health Sciences, a school noted for integrating quackery with medicine. The “sciences” this school teaches are listed at the top of its website: chiropractic medicine, naturopathic medicine, oriental medicine, acupuncture, biomedical science, and massage therapy. The only one of those that even sounds like science, “biomedical science,” offers a bachelor of science degree with an integrative medicine focus and with no required core courses whatsoever!

Their doctor of chiropractic degree program says:

National University prepares students to become first-contact, primary care physicians fully qualified to diagnose, treat and manage a wide range of conditions.


Posted in: Chiropractic, Politics and Regulation

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