TACT Study of Chelation Therapy Again in Spotlight

December 13, 2011

December 13, 2011 (Chicago, Illinois)The Trial to Assess Chelation Therapy (TACT), investigating the chelation therapy ethylenediaminetetraacetic acid (EDTA) in coronary heart disease patients, is once again the subject of controversy, this time in an article published yesterday in the Chicago Tribune [1,2].

The $30 million TACT trial, sponsored by the National Center for Complementary and Alternative Medicine (NCCAM) and the National Institutes of Health, was stopped in 2008 while "allegations of impropriety" were investigated. These centered on concerns over the patient-consent process. The trial was restarted in 2009.

Reviewing much of the previous controversy, the current Chicago Tribune article suggests, among other things, that there was not enough evidence suggesting benefit of chelation therapy in heart disease to justify conducting the trial and that some of the doctors involved in the trial have been in trouble with state medical boards or health departments. The article, by journalist Trine Tsouderos, also reports that two paid consultants to the trial had been convicted of federal crimes. Many of the criticisms of the trial have been reported previously, and TACT was the subject of a whole critical report published in the Medscape Journal of Medicine in 2008 [3]. Tsouderos told heartwire the current Tribune article was the second "of a series on NCCAM and was a look at one of the center's larger studies."

Lead Investigator Responds

In response to the Tribune article, lead TACT investigator Dr Gervasio Lamas (Mount Sinai Medical Center, Miami Beach, FL) commented to heartwire that EDTA chelation therapy has been postulated to produce a favorable effect on atherosclerotic plaque, and although evidence is limited, approximately 111 000 adults in the US used chelation therapy in 2007. "So patients are being exposed to the risks of this treatment in an uncontrolled fashion and are investing their own money in it. They deserve to know whether there is any evidence of efficacy."

In response to claims in the Tribune article that EDTA is unsafe and that this led to it being delisted by the FDA, Lamas points out that the trial is using the chelation therapy under an FDA investigational new drug (IND) application, which requires regular reports of adverse events. "Indeed, when used as directed within the guidelines of TACT, chelation therapy with EDTA has proved to be remarkably safe." He added that the trial has been the subject of a comprehensive inquiry and has been reviewed by many regulatory bodies, all of which have concluded that it should continue.

On the allegation in the Tribune article that the study misled patients regarding death as a potential side effect of chelation therapy, Lamas says: "Death can be a side effect when the therapy is delivered too quickly or in an incorrect dose. Much like Tylenol, when misused, an overdosage can have serious consequences. In the context of a tightly controlled clinical trial, we did not believe that death was a potential side effect when we developed the original consent form. . . . However, in response to a request from the Office of Human Research Protections the consent form was revised in 2009."

On the reports of misdemeanors of some of the investigators, Lamas notes that over 300 physicians have participated in the trial, "yet Ms Tsouderos focused on a small number of investigators who have had legal problems, unrelated to the trial."

Lamas also says Tsouderos's claim that the trial had difficulty enrolling patients is "misleading."

"Clinical trials--even those addressing 'mainstream' therapies--often have difficulty finding productive sites and enrolling patients. TACT has been no different in this regard."

He concludes: "Anyone who has studied the history of medicine knows that many effective mainstream therapies are derived from empirical folk remedies and that some science-based treatments prove ineffective or even harmful. As a practicing 'mainstream' cardiologist, I have no vested interest in establishing the value of chelation therapy, but I do try to keep an open mind on this issue. Since neither I nor any other TACT clinical investigators are privy to interim outcome data from TACT, we do not know how the study will turn out. Our job is not to prejudge its outcome but to maintain the safety of our participants and the scientific integrity of the study, as judged by those who review our data and practices regularly."

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