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    A closer look at the criticisms of chelation

    Looking at the flaws raised by Cleveland Clinic Cardiologist Steven Nissen — and the answers offered by study participants — offers some insight into what makes a study valid and trustworthy.

    Many of the clinics that conducted the trials were alternative therapy clinics and had not done research before. A clinical trial is only as reliable as the centers where it is conducted, and weak sites mean a weak study, Nissen said.

    The researchers said they included a variety of sites, some that had clinical trial experience, some that didn’t but had experience delivering chelation therapy. To re-create the way chelation is given in the community, said Gervasio A. Lamas, the Columbia University cardiologist who conducted the study, he had to include centers that actually deliver the treatment the way typical patients might receive it.


    Nissen also pointed out that the federal agencies paying for the research had access to the data while the trial was underway, potentially tainting the analysis. Officials needed access to the data during the trial to ensure patients weren’t being harmed, said Dr. Yves Rosenberg, chief of the coronary artery disease branch of the National Heart, Lung, and Blood Institute, which helped fund the research. But there were “very strict guidelines” and a firewall keeping those who knew about the results away from those conducting the study.

    Too many patients failed to complete the study, Nissen said, making the study “essentially uninterpretable.” Lamas explained that most of the drop-outs were getting the placebo, not the active drug – so, if the 18 percent drop-out rate skewed the results, the bias was against the drug, not for it. There were so many drop-outs, Lamas said, because chelation is an incredibly time-consuming process, requiring patients to give up a half-day a week for six months.