Chelation with intravenous EDTA (disodium ethylene diamine tetra-acetic acid) has long been used for heavy metal poisoning. It binds the metal ions and facilitates their excretion from the body. In recent years it has been used for many other indications that are not evidence-based, such as autism and coronary heart disease.
The Trial to Assess Chelation Therapy (TACT) was done to assess the effectiveness and safety of EDTA plus high-dose oral vitamins for preventing second heart attacks in patients who had already had one. An article on The People’s Pharmacy website portrays the study as strongly positive. The Graedons, authors of the website, claim that science supports the use of chelation. They report that for every 12 patients undergoing chelation, one heart attack will be prevented over a five-year period. They cite a 5-year NNT (number needed to treat) of 16 for statin therapy and they conclude that:
EDTA chelation outperformed statins because fewer people needed to receive treatment to achieve a desirable outcome.
Chelation is the provision of a substance to increase the body’s excretion of heavy metals. In poisoning situations (lead, aluminum, iron, etc.), chelation is medically necessary, objectively effective, and approved for use. But the same term has a completely different meaning in the alternative medicine universe, where proponents often believe heavy metal toxicity is the “one true cause” of disease, and chelation can undo microvascular inflammation, atherosclerosis, and even aging itself. From early days as an unproven treatment of coronary artery disease, its use has expanded to include autism, Alzheimer’s disease, cancer, and dozens of other diseases. Today, chelation is widely available. Regrettably, my own profession, pharmacy, facilitates this pseudoscience by manufacturing and selling chelation products.
Provoked urine tests are a common entry point to chelation therapy. Patients are given a product to provoke heavy metal excretion. The urine is tested and the patient is informed that they’re “toxic” and require chelation. Unfortunately, these results are meaningless and provide no evidence that chelation is medically necessary. But that’s the justification used for advocating a treatment regimen that will be useless at best and fatal at worst. A recent Medical Letter review concluded:
Medical Letter consultants believe that the use of chelation therapy in non-standard protocols for unsubstantiated indications should be discouraged. The results of provoked urine testing are not an acceptable basis for such treatment.
Providing chelation to patients isn’t a straightforward matter. It’s typically an intravenous infusion (though there are some oral products). Unless you’re part of the dubious TACT trial, which has administration centres across the United States and Canada, there are few products commercially available. For example, edetate calcium disodium (EDTA) is approved for sale in the United States but not Canada. Edetate disodium (also called EDTA) is not approved for sale in either country. But these products are widely available: they’re manufactured by pharmacists in pharmacies.
In May 2008, the article “Why the NIH Trial to Assess Chelation Therapy (TACT) Should Be Abandoned” was published online in the Medscape Journal of Medicine. The authors included two of our own SBM bloggers, Kimball Atwood and Wallace Sampson, along with Elizabeth Woeckner and Robert Baratz. It showed that the existing evidence on treating heart disease with IV chelation did not justify further study, and that the TACT trial was questionable on several ethical points. Their ethical concerns were taken seriously enough that enrollment in the trial was put on hold pending an investigation. It has now been re-opened after a few band-aids were applied to the ethical concerns. The scientific concerns were never addressed.
I have seen many critiques of the Atwood study, and not a single one has offered any cogent criticism of its factual content or reasoning. Most of them could have been written by someone who had not bothered to read beyond the title. Their arguments can be boiled down to a few puerile points that can be further simplified to:
(1) I believe the testimonial evidence that chelation works.
(2) Atwood and his co-authors are bad guys.
Now Beth Clay has chimed in with an article entitled “Study of Chelation Therapy Should Not Be Abandoned.” I found it truly painful to read, but even the worst has some value as a bad example. Clay’s article could be used for a game of “Count the Errors.” I will point out some of them below. (more…)