It always somewhat surprises me how some interventions never seem to die. Theophylline seems to have disappeared in the medical pantheon, but what comes around, goes around. I predict a resurgence of theophylline this century. Despite the recent study that shows, yet again, echinacea has no effect on colds, I predict the study will neither decrease the sales of echinacea nor prevent further funds being spent on clinical trials on its efficacy. Hear that JREF? I made predictions. I will await my million dollar check. Make it out to Mark Crislip.
Another therapy that refuses to be put to rest, or even to be clarified, is the use of cranberry juice for urinary tract infections. Pubmed references go back to 1962, and there are over 100 references. Firm conclusions are still lacking.
There is a reasonable, but incomplete, basic science behind the use of the cranberry juice for urinary tract infections. (more…)
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.
My stimulant of choice is coffee. I started drinking it in first-year university, and never looked back. A tiny four-cup coffee maker became my reliable companion right through graduate school. But since I stopped needing to drink a pot at a time, an entirely new category of products has appeared — the energy drink. Targeting students, athletes, and others seeking a mental or physical boost, energy drinks are now an enormous industry: from the first U.S. product sale in 1997, the market size was $4.8 billion by 2008, and continues to grow. (1)
My precious coffee effectively has a single therapeutic ingredient, caffeine. Its pharmacology is well documented, and the physiologic effects are understood. The safety data isn’t too shabby either: it’s probably not harmful and possibly is even beneficial. (I’m talking about oral consumption — no coffee enemas. Please.) In comparison, energy drinks are a bewildering category of products with an array of ingredients including caffeine, amino acids, vitamins, and other “natural” substances and assorted “nutraceuticals,” usually in a sugar-laden vehicle (though sugar-free versions exist). Given many products contain chemicals with pharmacologic effects, understanding the risks, signs of adverse events, and potential implications on drug therapy, are important.
So are energy drinks just candied caffeine delivery systems? Or are these syrupy supplements skirting drug regulations?
Echinacea continues to be a popular herbal product, used primarily for treating and preventing colds and flus. Sales were estimated at $132 million in the US alone in 2009, an increase of 7% over the previous year. Reports of major negative clinical trials have had only a modest and temporary effect on the popularity and sale of this herb, contradicting claims that the utility of such research is to inform consumers.
In the current issue of the Annals of Internal Medicine there is a new study of Echinacea for the treatment of cold symptoms: Echinacea for Treating the Common Cold, A Randomized Trial. I won’t hold out the punchline – the study was completely negative. But let’s put the results of this study into the context of the history of Echinacea and the clinical evidence.
History of Echinacea
Modern proponents of Echinacea frequently cite as support the claim that this plant has been used for centuries by many Native American cultures. This much is well-documented, but what is not clear is what Echinacea was used for. For this there is no clear answer, except that Echinacea was used for 15-20 different and unrelated conditions, from fatigue to snake bites. Let us consider the value of the claim for traditional use of any treatment.
One of the recurrent themes of science-based medicine is that any medical intervention that can plausibly cause physiological benefit can also plausibly cause physiological harm. There is no such thing as “it can’t hurt.” Sometimes the risk may be minuscule – but we should never assume that it is zero. Being “natural” or “holistic” or being blessed with some other alleged marketable virtue does not affect the risk vs benefit calculation of an intervention.
Vitamins are an excellent example. There is widespread sentiment that vitamins are harmless, and that supplementing with vitamins is therefore a no risk-possible benefit scenario. It is certainly reasonable to conclude from the evidence that vitamins (at usual supplemental levels) are low risk, compared to many other types of medical interventions. High doses, or megadoses, of vitamins, however, risk toxicity and this risk increases with the dose.
But even at sub-toxic doses vitamins should not be assumed to be risk free. This is especially true when we take a public health perspective – what is the net effect of large scale supplementation on the population? A new meta-analysis looking at the net effects of Vitamin E supplementation on stroke risk reinforces this caution.
The bar on this blog is set high. The entries are often complete, with no turn left unstoned. Yet, not every topic needs the full monty with every post. The blog has extensive evaluations on many topics, and new medical literature doesn’t require another complete analysis. Many new articles add incrementally to the literature and their conclusions need to be inserted into the conversation of this blog, like a car sliding into heavy traffic. My eldest son just received his driver’s license, and car metaphors are on my mind. As are crash metaphors and insurance metaphors.
So in response to this need, a need only recognized by me, I give you Short Attention Span SCAM. Occasionally I will summarize a few recent studies and their key points as they relate to prior posts at SBM.
I’m only a monthly contributor here but between being a SBM reader and having my own blogs, I often grow weary of the blind criticism that researchers and drug companies couldn’t care less about traditional folk medicines as drug products. My laboratory spends every single day working on natural product extracts in the search for compounds that may have selective effectiveness against cancer. So, this is a bit of a sore spot for me.
Two papers this week from Cancer Prevention Research on the potential anticancer effects of a diabetes drug (Nathan Seppa story here) remind me to tell the story of a Middle Ages European herbal medicine used to treat polyuria that gave rise to one of the most widely prescribed drugs in the world, metformin (Glucophage in the US). Metformin, known chemically as a biguanide, dimethylguanide to be precise, traces its roots to the plant Galega officinalis. Known as goat’s rue, French lilac, or professor weed, this plant was shown to be a rich source of guanidine and a less toxic compound later called galegin or galegine (isoamyline guanidine).
Age-related macular degeneration (AMD) is one of the major causes of visual impairment in the elderly: it affects central vision, impairing the ability to read and recognize faces while preserving some peripheral vision. It comes in two forms: wet and dry. Dry macular degeneration is by far more common, but wet macular degeneration, involving the proliferation of blood vessels, is more severe.
There is evidence that antioxidant vitamin supplementation may slow the progression of the dry type when it is already established and moderately severe, but the published evidence does not support the use of these supplements for prevention or for patients with early stages of the disease. Some people are using it for prevention, but there is concern that the risks might exceed any benefit. Of more concern, it appears that a manufacturer’s (Bausch & Lomb’s) advertising has gone way beyond the available evidence. (more…)
A recurring theme at SBM is the regulation of supplements, and the impact and consequences of the Dietary Supplement Health and Education Act of 1994 (DSHEA). As one of SBM’s international contributors, I thought it might be helpful to look at how the DSHEA stacks up against the equivalent regulations of its neighbor to the north, Canada. Given the multiple calls for overhauls and changes to DSHEA, an international comparison may help focus the discussion around what a more science-based framework could look like.
Briefly, the DSHEA is an amendment to the U.S. Federal Food, Drug and Cosmetic Act that establishes a regulatory framework for dietary supplements. It effectively excludes manufacturers of these products from virtually all regulations that are in place for prescription and over-the-counter drugs. The FDA notes:
Generally, manufacturers do not need to register their products with FDA nor get FDA approval before producing or selling dietary supplements. Manufacturers must make sure that product label information is truthful and not misleading. FDA’s post-marketing responsibilities include monitoring safety, e.g. voluntary dietary supplement adverse event reporting, and product information, such as labeling, claims, package inserts, and accompanying literature. The Federal Trade Commission regulates dietary supplement advertising.
Glucosamine is widely used for osteoarthritis pain. It is not as impossible as homeopathy, but its rationale is improbable. As I explained in a previous post,
Wallace Sampson, one of the other authors of this blog, has pointed out that the amount of glucosamine in the typical supplement dose is on the order of 1/1000th to 1/10,000th of the available glucosamine in the body, most of which is produced by the body itself. He says, “Glucosamine is not an essential nutrient like a vitamin or an essential amino acid, for which small amounts make a large difference. How much difference could that small additional amount make? If glucosamine or chondroitin worked, this would be a medical first and worthy of a Nobel. It probably cannot work.”
Nevertheless, glucosamine (alone or with chondroitin) is widely used, and there are some supporting studies. But they are trumped by a number of well-designed studies that show it works no better than placebo, as well as a study showing that patients who had allegedly responded to glucosamine couldn’t tell the difference when their pills were replaced with placebos. The GAIT trial was a large, well-designed, multicenter study published in The New England Journal of Medicine that showed no effect in knee osteoarthritis. A subsequent study of hip osteoarthritis also showed it worked no better than placebo.
A new study shows that glucosamine works no better than placebo for osteoarthritis pain in the low back. It was published in the JAMA: Effect of Glucosamine on Pain-Related Disability in Patients with Chronic Low Back Pain and Degenerative Lumbar Osteoarthritis: A Randomized Controlled Trial, by Wilkens et al. (more…)