Another Failure of Chelation Therapy

Chelation therapy is a long-time staple of medical quackery, but it isn't tested as often as it might be. Here's a curious report of a recent clinical test published in JAMA showing that chelation therapy chelationchelationdoesn't make any difference in heart attack, stroke, hospitalization, surgeries, etc, outcomes.

The report is curious -- and so is the publication of the article -- because the JAMA publisher editorializes against the use of chelation therapy yet the director of the study appears to be a believer, clinging to a very small improvement of outcomes for chelation when all the outcome variables are combined.

There is a strong editorial criticizing the methodology of the study, which unfortunately is behind a paywall that many won't be able to access. It notes that "clinics" purveying quack treatments were the sites of 60% of the work. This might help explain why of the approximately 1/6 dropouts of the study, more dropped out of the control group than the chelation group.

When there is withdrawal from a trial, it often is because the subjects have problems with side effects of the treatment; side effects of the placebo are by definition non-existent! The author of the critical editorial (Steven E. Nissen, MD, Department of Cardiovascular Medicine, Cleveland Clinic Foundation) suggests that this disproportionate loss of placebo subjects was a function of the probability that the study was not double blind. That is a hugely important claim that could invalidate the conclusions of the study.

Nissen brings up serious questions about the number of statistical analyses performed and the slow pace of data collection. Did they stop collecting data when they reached a point where (finally!) data reached some semblance of significance (a weak 0.35, btw)?

The concluding paragraph of Nissen's editorial:

"Given the numerous concerns with this expensive, federally funded clinical trial, including missing data, potential investigator or patient unmasking, use of subjective end points, and intentional unblinding of the sponsor, the results cannot be accepted as reliable and do not demonstrate a benefit of chelation therapy. The findings of TACT should not be used as a justification for increased use of this controversial therapy."

But wait, there's more! A second editorial reviewed the complex reasons why JAMA published this article (funded jointly by the National Heart, Lung, and Blood Institute (NHLBI) and the National Center for Complementary and Alternative Medicine (NCCAM), and costing $10 million dollars over 10 years), and spoke directly to purveyors of chelation treatments:

"This evidence and information should serve to dissuade responsible practitioners from providing or recommending chelation therapy for patients with coronary disease and should discourage patients with previous MI from seeking this therapy with the hope of preventing subsequent cardiovascular events."

Prediction: promoters of chelation therapy will seize this article as evidence that their treatment works, ignoring the serious problems with the research, and the negative results that dominate the study -- even with the probable unblinding and sample bias.