Medical device risk management and safety cases.

Abstract

Safety assurance cases have been used in different industry sectors such as nuclear power, transportation, and military systems for many years. In 2010, the U.S. Food and Drug Administration (FDA) launched the Infusion Pump Improvement Initiative to address observed infusion pump safety problems. As part of this initiative, the agency began to review safety assurance cases submitted within premarket device notifications for drug infusion pumps.1 At this time, the FDA has not specified a format for safety assurance case submissions. Therefore, seeing a wide variation in safety case organization, content, and soundness is not surprising. Based on review of numerous safety case submissions received to date, a common approach followed by many manufacturers has been to convert existing risk/hazard analysis work (typically presented in tabular format) to a graphical representation. The result, in general, was numerous diagrams that were difficult to review, comprehend, and develop confidence in. This report discusses how artifacts from a risk management process based on ANSI/ AAMI/ISO 14971:20072 might be organized into a safety assurance case and how the safety case development process can contribute to the risk analysis process. Notions of argument and evidence sufficiency and their relationship to confidence are introduced. A sample risk analysis and safety case pattern using ANSI/ AAMI/ISO 14971:2007 artifacts are presented. Also, a sample design safety case template is presented that demonstrates how the safety case approach is broader than ANSI/AAMI/ISO 14971:2007. The terminology used in this article is based on ANSI/AAMI/ISO 14971:20072 and ISO/IEC TR15026-1:2010,3 though certain terms are not explicitly defined in these standards.