There has never been a scientific study of EDTA chelation that did not show effectiveness, although there have been reports in which positive data were erroneously interpreted as negative. Reports of negative or adverse results from EDTA chelation following the currently approved protocol have been either editorial comments and letters to the editor written by opponents of this therapy or seriously flawed attempts to discredit chelation with biased and unscientific interpretation of data--sometimes by cardiovascular surgeons who freely admit their bias.(75,84-89)
In the last ten years, a small cluster of studies has sprouted up in the medical literature purporting to demonstrate that EDTA chelation is not effective in treatment of cardiovascular disease. Although flawed and imperfect, those studies in actuality provide only positive support for chelation. Their negative conclusions are not supported by the data.
The Danish Study
The most controversial and oft cited study of that type was done in Denmark. It was the handiwork of a group of Danish cardiovascular surgeons who freely admitted their opposition to chelation. Results of that study were published in two medical journals, the Journal of Internal Medicine and the American Journal of Surgery.(84-85) Adverse conclusions were also widely publicized in the news media.
The surgeons who conducted that study followed 153 patients suffering from intermittent claudication. The patients had such severely compromised circulation in their lower extremities that walking a city block or less would cause them to stop with pain. An endpoint measured for this study was their maximal walking distance (MWD)--the very longest distance that they could walk before pain of claudication brought them to a halt. Patients were equally divided into an EDTA group and a placebo group. In the pre-treatment phase, the EDTA group averaged walking 119 meters before pain stopped them; the placebo group was less limited at the outset and averaged 157 meters.
Treatment was either 20 intravenous infusions of disodium EDTA or 20 infusions of a simple salt solution, depending on their group. Although the study was alleged to be double-blinded (neither patients nor researchers were supposed to know who received placebo and who received EDTA), the researchers later admitted that they broke the code well before the post-treatment final evaluation
Both groups showed improvement, and the investigators concluded that the improvement was not statistically significant. This Danish study turned many people against chelation; but, in rather short order, the integrity of the study was called into question. It was learned that the researchers had violated their own double-blind protocol. Not only did they themselves know before the end of the study who was receiving EDTA and who placebo, they had also revealed this information to many of the test subjects. Before the study was over more than 64 percent of the subjects were aware of which treatment they had received. This was highly questionable from an ethical and scientific standpoint.
One important aspect of the Danish study is the startling fact that the patients who were given EDTA were much sicker than the patients treated with a placebo. Therefore, the improvements the EDTA group made were harder earned and more significant. The researchers (who candidly admitted that they undertook the study to convince the Danish government's medical insurance NOT TO PAY for chelation) either never noticed that aspect or felt reluctant to reveal it. The evidence is seen in the pre-treatment MWDs, 119 meters for the EDTA group and 157 meters for the placebo group.
Still more significant was the standard deviations The plus or minus 38 meters SD for EDTA patients versus the plus or minus 266 meters SD for the placebo group represents an enormous variation in walking capacity that is heavily biased in favor of the placebo group. Those standard deviations show that some placebo patients must have walked half a mile before stopping. The placebo group’s claudication was therefore markedly less severe, and the EDTA group was much more severely diseased. The design of the study was obviously biased against EDTA chelation from the outset.
Yet, when the six-month study was completed the mean MWD in the EDTA group increased by 51.3 percent, from 119 to 180 meters, while the mean MWD in the placebo group increased only 23.6 percent, from 157 to 194 meters. The chelation group’s improvement was therefore more than twice as great as the placebo group’s, even though the chelation group was significantly sicker at the outset. This is a positive study, supporting the usefulness of EDTA chelation. The authors’ published negative conclusions are not supported by the data.
The New Zealand Study
Another study--also conducted by cardiovascular surgeons--was done at the Otago Medical School in Dunedin, New Zealand, two years after the Danish study. The subjects of this study were also suffering from intermittent claudication. The subjects were divided into two groups, the EDTA group and the control group. The study extended to three months after 20 infusions of either EDTA or a placebo were given. The authors concluded that EDTA chelation had been ineffective. Once again, that conclusion was unsupported by their data.(86-87)
Absolute walking distance in the EDTA group increased by 25.9 percent; while in the placebo group, it increased by 14.8 percent. The difference was not considered statistically significant. The study, however had only 17 subjects in the placebo group. One of the placebo patients was what the statisticians call an “outlier,” whose results differ strikingly from everyone else in the group. This patient’s walking distance increased by almost 500 meters. All of the statistical gain in the placebo group was due to this one individual’s progress. Without him, the placebo group’s distance actually decreased.
This illustrates the perils of a small study. The 25 percent gain in the EDTA group compared to no gain in the placebo group would have been very significant statistically.
In addition, the New Zealand researchers did concede that improvement in artery pulsatility (pulse intensity) in the EDTA group’s worse leg improved enough to reach statistical significance (p<0.001).
A 25.9 percent improvement in walking is by no means minor and would attract notice if the agent had been a patentable drug. Even that level of improvement is not representative of the much greater improvements claudication patients normally experience after chelation. The below expected improvement seen in this study can be explained by smoking. Eighty-six percent of the chelated subjects were smokers. Although they were advised to quit smoking when the study began, how many of them actually complied is not known.
The Heidelberg Study
Another study that was carried out with an erroneous negative conclusion is the “Heidelberg Trial,” funded by the German pharmaceutical company Thiemann, AG in the early 1980s. A group of patients with intermittent claudication were given 20 infusions of EDTA and compared with a so-called “placebo” group which was actually given bencyclan, a pharmacologically active vasodilating and antiplatelet agent owned by Thiemann.
From a practical commercial standpoint, Thiemann’s action was bizarre. If EDTA did well in the trial, Thiemann’s well-established drug could only suffer. Nonetheless, the trial went forward and was reported in 1985 at the 7th International Congress on Arteriosclerosis in Melbourne, Australia.(87) Immediately following 20 infusions of EDTA the trial subjects’ pain-free walking distance increased by 70 percent. By contrast, patients receiving bencyclan increased their pain-free walking distance by 76 percent. The difference between these two results was not statistically significant, but another result was. Twelve weeks after the series of infusions was completed, the EDTA patients’ average pain-free walking distance had continued to increase, going up to 182 percent. No further improvement had occurred in the patients receiving bencyclan. Those percentages were never published.(87)
An informal report from Thiemann mentioned only the 70 and 76 percent figures. Press releases stated that chelation was no better than a placebo, but failed to mention that the “placebo” was a drug that had been proven effective in the treatment of intermittent claudication. Thiemann never released the actual data on which the Heidelberg Trial based its conclusions, but some German scientists who had access to it, and who were disturbed at the deception they were witnessing, chose to reveal the complete raw data to members of the American scientific community.
The complete data showed that four patients in the EDTA group experienced more than a 1,000-meter increase in their pain-free walking distance following treatment. That highly significant data from those four patients mysteriously disappeared before the final results were made public. Thiemann had a legal right under terms of their contract to edit the final results and to interpret the data in any way that suited them. A subsequent analysis of the data, with the four deleted patients included, showed an average increase in walking distance of 400 percent in the EDTA treated group--five times the 76 percent increase of the group receiving bencyclan.(89)
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