Chelation therapy, a 1950s treatment for lead poisoning that has become an increasingly popular alternative medicine treatment for conditions as diverse as autism and heart disease, received a lukewarm endorsement from a government-funded clinical trial that is drawing criticism for its methods and the possibility of investigator bias.
The results of a controversial 10-year, $31 million, National Institutes of Health-funded study, published in this week's Journal of the American Medical Association, showed a small reduction in the risk for subsequent cardiac events in patients receiving chelation therapy after a heart attack. An accompanying editorial by Dr. Steven Nissen of the Cleveland Clinic criticized the study for its high dropout rate, changing of trial design midway through the study, its missing data, investigator biases and the intentional unblinding of the sponsor.
Chelation therapy involves infusion of ethylene diamine tetraacetic acid, or EDTA, to promote the removal of substances such as lead, cadmium, calcium and aluminum from the body and into the urine. Ethical complications of the study included the potential risk of abnormally low calcium levels in the blood and a scientific consideration included the high number of participants who withdrew from the trial.