February 2015

How Can Industry Handle Safety Assurance Cases?

Sherman Eagles
Sherman Eagles
Fubin Wu
Fubin Wu

Fubin Wu, cofounder of GessNet, which offers solutions for risk management, cybersecurity, and regulatory compliance, and Sherman Eagles, partner at SoftwareCPR, offer advice on complying with U.S. Food and Drug Administration guidance that includes safety assurance cases.

This past December, the U.S. Food and Drug Administration (FDA) published final guidance to assist industry in preparing premarket submissions for infusion pumps. It also includes information on the device features manufacturers should address throughout the total product life cycle.

The FDA has aligned this guidance with its mission to protect public health. "The recommendations in this guidance are intended to improve the quality of infusion pumps in order to reduce the number of recalls and adverse events associated with their use. The FDA believes that these recommendations will help mitigate current risk and reduce future risk associated with infusion pumps."

Significantly, according to the agency, infusion pump manufacturers should maintain safety assurance cases through the product life cycle. A safety assurance case is a report that consists of an argument supported by scientific evidence to show that a device under premarket review is as safe and effective as a similar device that's already been approved and on the market.

With the final guidance, FDA lays out further details and clarification on safety assurance cases compared with the draft guidance, which was issued in April 2010.

After more than four years of piloting the safety assurance cases, both industry and FDA have developed a better understanding of the safety assurance case method, as well as the practical application of it to medical devices, such as infusion pumps. It appears as if the FDA has incorporated these experiences from these pilots into the final guidance, as shown in these statements in the final guidance:

  • "A separate argument structure demonstrating the completeness of the hazard analysis process, including techniques, procedures and results to assure that hazards present within the safety case are accurate and complete. This concept is often referred to as a confidence case."
  • "We encourage you to leverage your existing risk management activities to avoid duplication in the development and documentation of your safety case."
  • "As part of the safety assurance case, the analyses and associated activities may take the form of claims, arguments, or evidence."
  • "To maximize the benefit of the safety case, you should maintain and refine your safety case throughout the life of the infusion pump. During development, maintenance, and refinement of your safety case, you should address the full lifecycle of the infusion pump within your safety case."

AAMI Report Aims to Demystify Assurance Cases

A new technical information report (TIR) from AAMI provides guidance on the development of safety cases for the design of a medical device. TIR38:2014, Medical device safety assurance case guidance, describes how to create a safety case model for a new and previously existing device. It also advises manufacturers to develop these cases early. "To realize the full benefit the safety case development process must be ongoing during product design," according to the report. "In this way, the designers can appropriately address new hazards and faults as they arise and better inform and document the design tradeoffs and choices they make."

List Price: $150 | Member Price: $90 | Order Code: TIR38 or TIR38-PDF | AAMI Store

"Safety Assurance Cases for Medical Devices," our article published in the January/February 2014 edition of BI&T (Biomedical Instrumentation & Technology) provided some tips for manufacturers. We noted that a solid safety assurance case requires sound risk management practices. To meet the final guidance expectation on safety assurance cases, the device manufacturers should perform both top–down risk analysis (e.g., preliminary hazard analysis, fault tree analysis) to address "failures caused by system, sub-system, or component interactions," as well as a bottom–up risk analysis to address "common cause failures," subsystem, or component failures.

The final guidance provided a list of system hazards (i.e., infusion delivery error, incorrect therapy, biological/chemical contamination, and traumatic injuries) that are common to infusion pumps. Manufacturers should include a demonstration of how these system hazards and causes are addressed by a particular device, in addition to a description of how they have addressed unique hazards derived from individual system design. Without the use of proper risk analysis techniques, it would be difficult to meet this expectation.

Although safety assurance cases have been used for many years in mission-critical systems in the defense and transportation industries, their practical application to medical devices is still at an early stage. We see promise, however, as those who have used these cases and understand them strongly believe they are valuable in ensuring device safety.

Currently, there is no indication that the FDA plans to expand the requirement of safety assurance cases on devices beyond infusion pumps. However, it is not unreasonable—given the FDA's mission—for agency reviewers to ask questions using the safety assurance case method during the premarket clearance/approval process.

Manufacturers may initially find there is more work to be done to meet the expectation of the final guidance. However, if practicing the new method described in the guidance offers a promising means to reduce recalls and adverse events, the return on investment in implementing this guidance will not just be compliance, it will mean safer medical devices that benefit both the manufacturers and all of us.

The views expressed in this commentary are strictly those of the authors and do not reflect formal legal or regulatory guidance.