Wednesday, July 30, 2008

Experts examine key issues related to post-market evaluation of medical devices
By Maggie De Pano

Researchers from the Duke Clinical Research Institute (DCRI) recently released the results of a meeting where experts representing the medical devices industry, regulatory authorities, academic medicine, and professional societies discussed key issues related to the post-market (or “real world”) evaluation of medical devices used to treat cardiovascular disease.

The results were published in the August 2008 issue of the American Heart Journal.

The meeting, titled “Post-Market Evaluation of Breakthrough Technology: A Summit on Issues and Approaches,” took place in February 2004, when high-profile cases involving dangerous defects in widely used medical devices such as drug-eluting stents and implantable cardioverter-defibrillators were beginning to emerge. It was sponsored by the DCRI and the American College of Cardiology (ACC).

A think tank of experts examined case studies, pointed out limitations in the current system of device monitoring and reporting, and proposed possible solutions to problems related to the post-market evaluation of medical devices. They identified the following problems:

• There are limits to the accuracy and efficiency of post-market evaluation systems used by the FDA’s Center for Devices and Radiological Health. These include underreporting of post-market adverse events; a mix of reporting styles with no standard source document verification; and the absence of a standard that accommodates differences between immediate surges or clusters of adverse events and real safety issues.

• It is difficult to decide what event rate – defined as the proportion of patients in a group in whom the event is observed – to use when reporting an adverse event. For example, should the rate of subacute thrombosis (blood clot) be expressed as a percentage of patients receiving a drug-eluting stent? Or, given that many patients receive more than one stent in more than one artery, is it more appropriate to calculate the rate as a percentage of stents or of vessels?

• It is difficult to define the etiology (cause) of certain adverse events. These include unanticipated allergic reactions to drugs, unexpected device performance issues related to design or stages of manufacturing, and operator-related technical errors.

• There is widespread off-label use of medical devices. Off-label use is the practice of using a device for purposes outside the scope of its approved label.

• There are no incentives for device manufacturers to conduct post-market monitoring. Additional studies or surveillance may be regarded as high on liability and cost but low on value, since the data they produce generally do not support new or extended product uses.

The experts then proposed the following solutions:

• Improve and enforce current FDA regulations by adding staff to the Center for Devices and Radiological Health’s post-market surveillance group, providing greater support for compliance oversight and manufacturing inspections, and allocating more resources, including the legal authority to enforce FDA mandates;

• Consider creative study design strategies that link pre- and post-market data;

• Declare post-market surveillance a public health issue;

• Create financial incentives for participation in post-marketing studies;

• Emphasize the value of retrieving, collecting and analyzing devices with performance issues, especially in settings where postmortem retrieval is conceivable; and

• Align professional societies with the FDA to evaluate breakthrough technologies and communicate findings to patients and clinicians.

The researchers concluded that addressing important safety issues will likely help provide safe and effective medical technology to stem the tide of cardiovascular disease despite the accelerated pace of development and the increasing complexity of medical devices.

The results of the 2004 meeting were outlined in a report authored by the DCRI’s Sunil V. Rao, MD; Robert M. Califf, MD; Judith M. Kramer, MD; Eric D. Peterson, MD; and Mitchell W. Krucoff, MD.