Information on the safety and effectiveness of medical devices before and after they are cleared by U.S. health regulators can be improved, according to two new studies.

One study found many U.S. Food and Drug Administration (FDA)-cleared medical devices meant to be implanted in the body were not backed by publicly available evidence that they are similar to a device already on the market.

“Let the buyer beware before getting an implant in their body, because there may be no evidence the implant is going to benefit them and no study done in case it might harm them,” said Diana Zuckerman, the study’s lead author and president of the National Center for Health Research in Washington, D.C.

The new report is not the first time researchers have criticized the process the FDA uses to evaluate many medical devices.

In 2011, the Institute of Medicine issued a report that the medical device evaluation process known as 510(k) is fatally flawed and should be replaced. The FDA, which requested the report, disagreed. (See Reuters story of July 29, 2011 here:

The 510(k) process allows medical devices to get to market faster if they are “substantially equivalent” to devices already being sold. Certain information that’s submitted to the FDA about the devices must be made publicly available as a summary, Zuckerman and her colleagues write in JAMA Internal Medicine.

For the new study, the researchers evaluated the publicly available information for implantable devices cleared by the FDA through the 510(k) process between 2008 and 2012. Because those devices are supposed to be similar to another device already on the market, the researchers also looked at the available information for those original devices.

Overall, they were looking for information on 50 devices cleared between 2008 and 2012 and 1,105 previously cleared devices.

They found enough evidence to support the claim that eight (or 16 percent) of the 50 new devices were substantially equivalent to previously cleared devices. Of those previously cleared devices, only 31 (or about 3 percent) were supported by publicly available evidence.

“The study relied on publicly available information, and as noted by the authors, this information is generally limited because manufacturers are only required by law to provide either a safety summary or a safety statement for the public,” the FDA said in a statement to Reuters Health.

“However, the FDA reviews a significant amount of data – far more than what is publicly available – to determine whether or not to clear an implantable device under a 510(k). This approach has served the American public well by balancing the need for robust evidence to assure safety while expeditiously bringing new technologies to the patients who need them,” the statement continued.

Zuckerman said the companies are not providing sufficient summaries of its evidence, which are required by law.

“I think this is a report card going forward,” she said. “Clearly the FDA and companies are failing to provide information to doctors and patients so they can make reasonable judgments to affect their lives.”

In another study in the same journal, researchers led by Ian Reynolds at The Pew Charitable Trusts in Washington, D.C. found that barriers may decrease the usefulness of studies completed after medical devices are approved by the FDA.

The researchers found the FDA ordered more than 223 studies for 158 medical devices between the start of 2005 and the end of 2011. Only one of the studies led to an action by the FDA other than a change of the devices label.

“We encourage the agency to work together with all stakeholders to evaluate how these studies can more effectively be used to improve the public health,” they write.

In a commentary accompanying the new study, Elisabeth Dietrich from the University of California, San Francisco and Maryland’s Secretary of Health and Mental Hygiene Dr. Joshua M. Sharfstein write that the FDA has already taken steps to address many of the issues pointed out in the new studies.

“It is important to recognize and support this progress, even as the FDA’s performance continues to be monitored through research and oversight,” they write.