Implanted medical devices need to be cleared for market by the FDA prior to use.
The study, published in JAMA Internal Medicine draws specific attention to a process called the 510(k) review, in which devices that are deemed to be moderate- to high-risk must be proved to be equivalent to another device (referred to as a "predicate") that has already been lawfully approved for market.
Around 400 implanted medical devices considered to be moderate- to high-risk, such as hip implants and surgical mesh, are approved for market every year in this manner. Moderate- to high-risk devices make up around one third of new devices requiring approval.
The authors of the study point out that "the FDA [Food and Drug Administration] refers to devices as 'cleared for market' through the 510(k) process rather than 'approved.'" They claim that clearing a device for market in this way is not a determination that the device is safe or effective but merely that it is "substantially equivalent" to another device that may have never been "systematically assessed for safety and effectiveness."
In addition, the Safe Medical Devices Act of 1990 states that scientific evidence submitted for the 510(k) process must be made publicly available in the form of a summary provided to the FDA by the manufacturer.
The summary must detail the basis for claiming substantial equivalence with a predicate device and discuss any tests carried if this claim was reliant on performance data. As these testing data can be nonclinical, this process effectively enables devices to be cleared for market without undergoing any specific clinical testing.
Diane Zuckerman, of the National Center for Health Research, Washington, DC, and her colleagues set about examining the evidence that manufacturers were submitting to the FDA, and whether or not this information was subsequently being made publicly available.
A lack of publicly available scientific data
For the study, the authors identified the first two implanted devices approved for the market in each of five different categories - cardiovascular, dental, general and plastic surgery, neurological and orthopedic - each year from 2008-2012.
The authors also identified 1,105 "predicates" that were listed by the manufacturers as devices already on the market to which the new medical devices were substantially equivalent.
Of these 50 newly cleared implants, the researchers found that scientific data were only publicly available to support claims of substantial equivalence for eight devices (16%). Of the 1,105 predicates, only 31 (3%) had publicly available scientific data to support their substantial equivalence.
Most of the evidence that was publicly available was found to be nonclinical data, and only some of it provided an evaluation of the safety or efficacy of the devices in question.
The authors say that scientific evidence for substantial equivalence is important for two reasons. Firstly, if a predicate device is recalled for safety reasons, use of the new medical device will be called into question.
Secondly, differences can accumulate from predicate to predicate. Some manufacturers would cite multiple predicates if their new device had a variety of features that needed accounting for. Using different materials and different anatomical sites could lead to different health implications for patients.
"For implants cleared between 2008 and 2012, however, we repeatedly found that scientific evidence of the substantial equivalence, safety, or effectiveness of medical devices was not publicly available in accordance with the legal requirements," write the authors.
"To protect the public health and allow for independent judgment of the quality of the scientific evidence that supports the marketing of medical devices, the FDA should enforce the law," they add.
In a related commentary to the study, Elisabeth M. Dietrich and Dr. Joshua Sharfstein point out that in 2009, a comprehensive assessment of the 510(k) program was instigated by the FDA in response to criticisms raised against it.
They state that concerns raised by Zuckerman and colleagues' study - the citing of multiple predicates in a claim of substantial equivalence and a lack of adequate scientific information in publicly available summaries - are directly responded to through improvements made following this assessment:
"The creation of the new pathway for [devices with no substantial equivalence], the improved training of FDA reviewers, and the FDA's draft guidance for 510(k) submissions are directly responsive to the concerns that are raised by this study."
"Over time," they write, "these measures should lessen concerns about the lack of publicly available scientific evidence on the safety and efficacy of medical devices cleared for market through the 510(k) process."
The FDA have to ensure that medical devices available to the public are both safe and efficacious while at the same time being delivered and regulated in a timely fashion. It is a balancing act that will continue to be scrutinized, but Dietrich and Sharfstein urge that any progress made be both recognized and supported.
Earlier this year, Medical News Today reported on an analysis of FDA warning letters that revealed the concerns of patients regarding safety during clinical research trials.