The US Food and Drug Administration (FDA) is responsible for approving drugs for medical uses, and the agency has developed a set of expectations for using results from randomized clinical studies to determine (with varying degrees of success) whether a drug is safe and effective. But advances in materials science and miniaturization have led to an explosion in the use of medical implants, which do everything from acting as a replacement for balky knees to restarting arrhythmic hearts. Two new evaluations of the clinical studies used during the implant approval process suggests that the approval process for implants isn’t nearly as rigorous as it might be.

The significance of the FDA’s approval is made clear by the authors of one of the evaluations, which was published yesterday by the Journal of the American Medical Association. As is the case with drugs, many physicians view the FDA’s acceptance as an indication that a device is safe and effective, as do many insurance companies. The makers of the implants, for their part, often view approval as a sign that it’s safe to begin a direct-to-consumer advertising campaign for their product.

And, to a certain degree, the implant makers are right. Last year, the Supreme Court ruled that FDA approval of a medical device prevents consumers from suing based on claims that the device is poorly designed or unsafe. In short, FDA approval confers an important validation on an implant.

Despite its centrality, the agency has only been in the implant approval business since the 1970s. The rate of implant development has also increased dramatically during the last few decades, during which time the agency has revamped its drug approval process and dealt with some high-profile cases of political and industry interference. Thus, an evaluation of its procedures for implant approval would seem timely, which may explain why two such evaluations are being released at the same time.

The JAMA study is being joined by one sponsored by the FDA itself, which will appear in the American Journal of Therapeutics. Both look at clinical studies that accompanied the Premarket Approval (PMA) submissions from various implant makers that occurred between 2001 and 2008, focusing on those devices that can easily be considered the most critical: cardiac implants such as stents, defibrillators, ventricular assist devices, etc. The two cover a variety of similar measures of the scientific rigor of these studies, but come to some significantly different conclusions about the significance.

So, for example, the JAMA study highlights how over half of the PMAs were supported by only a single clinical study. Only a quarter of these were randomized, and less than 15 percent were blinded, meaning those taking part in the study didn’t know who was receiving the new technology. Only about half included a control population. For drug approval, a randomized, double-blind trial has become the gold standard, so it might be a bit surprising that so few of these fit that description. However, the authors of the JAMA

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