The first attempts by infusion pump manufacturers to develop "assurance" cases to validate product safety in 510(k) submissions have not been particularly successful, according to FDA.

"I know it's new for everybody, but it seems that the manufacturers haven't thought about the safety issues," says Richard Chapman, acting head of CDRH's General Hospital Devices review branch.

"The hazard analyses that we get in are very inadequate, in most cases," Chapman said during an Aug. 24 Association for the Advancement of Medical Instrumentation web session.

In April, CDRH issued draft guidance requesting assurance case reports in 510(k) submissions for infusion pumps. It is part of a broad-based initiative to address persistent safety problems with the devices (¹ Also see "FDA To Impose New Pre-market Requirements On Infusion Pump Makers" - Medtech Insight, 3 May, 2010.).

Assurance cases are a formal method, used in the nuclear and avionics industries, among others, and increasingly by the device sector in Europe, for laying out claims and supporting evidence in almost a legal-brief manner. They are intended as a means to more directly demonstrate device-specific safety compared to conventional evaluation of processes for compliance to regulations and standards.

Although the assurance case requirement is currently only in draft form, reviewers are already asking sponsors to comply, Chapman said.

So far only three 510(k)s have been submitted with assurance case reports (of five post-draft-guidance submissions). In addition, reviewers are examining two more assurance cases that came with clinical evaluations under pre-investigational device exemption review, the acting branch chief said.

Based on that limited experience, reviewers are noticing that "the device is safe within a much narrower indication," than what manufacturers are calling for in their submissions, Chapman observed.

He warned that of the safety cases CDRH clinicians had seen so far, "within minutes, [they] were able to identify holes in these cases."

"The population that the device is supposed to be used on should not be so widely stated in the indication. And there has been a lot push-back from some of the [device] sponsors on that," Chapman said.

Rigorous Argument Key To Successful Cases

Done right, rather than just being one more piece of bureaucratic documentation required by an agency, the safety assurance case report can provide crucial evidence that will result in cost savings by avoiding accidents and recalls, increase confidence in device safety and ensure "a faster, more assured certification process," said John Knight, Ph.D., University of Virginia computer science professor and assurance case expert, during the AAMI session.

But it can't be an afterthought, Knight stressed. "A comprehensive and defensible argument" needs to be developed for the safety of each system and sub-system, he said.

For infusion pumps, that means validating that each potential hazard - operational, electrical, hardware and chemical - has been identified properly and checked; that hazards have been mitigated by engineering; that design analysis is completed to mitigate risks; and that assumptions are deemed appropriate.

And once clear-cut arguments are laid out, manufacturers should consider the best way to present them so reviewers can easily follow along, he suggested. CDRH's Chapman recommended that manufacturers present safety cases using graphic notation such as diagrams or flow charts.

The center is still reviewing how it will address assurance case reports over the long term, Chapman said. The infusion pump draft guidance is under review and a final guidance is expected by October.

Separately, officials are discussing the prospects of requiring assurance cases for 510(k)s in other product categories. The idea was included in the device center's Aug. 4 510(k) reform proposals (² 'The Gray Sheet' Aug. 9, 2010).

But, Chapman noted, "We want to gather information on the infusion pump first."

- Sue Darcey ( ³ s.darcey@elsevier.com )

Early Infusion Pump "Assurance" Cases Inadequate, CDRH Branch Chief Says

More from Archive

More from Medtech Insight