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Researchers at the Yale School of Medicine have found that the Food and Drug Administration’s De Novo pathway — a process of making risk-based evaluations of certain medical devices — has cleared moderate-level risk medical devices that did not meet the FDA’s own criteria for effectiveness and safety.

The team, led by James Johnston MED ’22, analyzed publicly available data provided by the FDA. The data described the clinical studies conducted in order to clear medical devices for patient use. The researchers found that over one-third of the devices failed to meet at least one of the primary effectiveness criteria in their respective “pivotal clinical trial” — the FDA’s process for evaluating the safety and the effectiveness of a given device. Johnston’s study also found that around one-fifth of the devices were not evaluated using this type of study.

“The [De Novo] pathway is being more commonly used and recently gained prominence,” Johnston said. “So we thought it would be interesting to look at the data behind these devices.”

FDA spokesperson Nicole Mueller wrote to the News in an email that the FDA does not comment on specific studies but rather “evaluates them as part of the body of evidence to further our understanding about a particular issue and assist in our mission to protect public health.”

The FDA categorizes medical devices in three tiers, based on their risk: Class I, II and III. Class II devices are considered to pose moderate risk to a patient’s safety, and is the category under which most medical devices fall. An example of such a device is a pregnancy test kit.

Vinay Rathi MED ’16, another author of the study, explained that the FDA created the De Novo pathway to decrease the barriers manufacturers face when creating low- to moderate-risk devices that use similar technology to previously-approved instruments.

“Patients often assume devices are effective because the FDA has cleared them for use,” Rathi wrote in an email to the News. “But [they] may be less willing to undergo the risks of implantation and explantation procedures if physicians help them understand gaps in the evidence.”

Rathi also highlighted the potential consequences of poorly evaluated devices for patients. According to Rathi, one of the devices they came across in their research was meant for long-term implantation in the body. This sort of device may have serious risks, but is still included in the same risk category as a pregnancy test, due to the wide range of medical devices contained in the Class II group.

Johnston explained that another reason the FDA created the De Novo pathway was to respond to criticism from the medical device industry, who believed the regulations for low- and moderate-risk devices were too stringent and discourage innovation.

“The problem for the FDA is that there is a constant battle between clearing the devices quickly, which patients want and the industry wants, and trying to make sure that those devices are safe and effective,” Johnston said.

Both Johnston and Rathi emphasized that their study was not meant to be a criticism of the FDA. Johnston does not believe that the administration is underperforming in their evaluation of the devices, but that the volume and the variety of clearance requests was previously too high. According to Johnston, the FDA had to find a more effective way to help companies clear their devices, so it attempted to address the issue by creating the De Novo pathway.

According to Rathi, the study’s main goal is to shed light on the possible limitations in medical device clinical evidence for both the public and the FDA itself. He believes the study could help inform improvements in the De Novo pathway and make the clearance of medical devices safer.

Rathi suggested that the FDA apply stricter standards during its approval process to ensure that all devices cleared for marketing are effective. He also mentioned the importance of performing post-market studies to reaffirm that there are no gaps in the pre-market findings for the device.

According to Johnston, despite the importance of having devices quickly made available to patients, it is also necessary to verify their safety.

“I’m in favor of the FDA implementing stronger preapproval clinical evidence for medical devices, erring on the side of more evidence is good,” Johnston said.

Johnston said that he will continue to study the safety of drugs and medical devices and their supporting evidence. He emphasized that it is important to continually look at the data and provide the public with accurate information on these devices.

According to Mueller, “The FDA is reviewing the findings of the paper.”

The Food and Drug Administration was founded in 1848.

Beatriz Horta |

Correction, Oct. 30:  A previous version of this article stated that Johnston’s study found one-fifth of the devices were cleared without any evaluative study. In fact, these devices were evaluated — but not by a pivotal clinical study. Also, the article incorrectly stated that Class II contains moderate and high risk devices. It has been updated to reflect that the devices are exclusively moderate risk devices.

Beatriz Horta is a staff reporter from Rio de Janeiro, Brazil covering the School of Medicine, School of Nursing and medical research. She's sophomore in Trumbull College majoring in psychology and MCDB.