Avoiding ISO 14971 Mistakes — Are You Accurately Defining "Hazardous Situations"?
By Naveen Agarwal, Ph.D., principal and founder, Creative Analytics Solutions, LLC
Identification of hazards, hazardous situations, and harms is foundational to analyzing the risks associated with a medical device. Yet, these terms are often misunderstood and misapplied in the industry. As a result, there is a lot of confusion and inconsistency in the implementation of risk management systems to meet the requirements of ISO 14971.
In the first part of this three-part series, we discussed the term “hazard” in detail. In this second part, we will review the term “hazardous situation” and provide examples to illustrate how you can define potential hazardous situations during risk analysis of your medical device.
ISO 14971:2019 defines a hazardous situation as a circumstance that exposes people, property, or environment to one or more hazards.
In other words, it is a situation where harm may occur due to exposure to one or more hazards. A related concept to understand is “foreseeable sequence of events” leading to a hazardous situation. Typically, there is a trigger event which cascades into a series of events that eventually lead to a hazardous situation for a patient, property, or the environment.
Consider a continuous glucose monitoring (CGM) device used to control the delivery of insulin in a closed-loop diabetes management system. If the CGM device malfunctions, it may trigger the pump controller to either overdeliver or underdeliver insulin compared to the target amount required. If an insufficient or excessive amount of insulin is delivered, the user may then experience a hazardous situation of either hypoglycemia or hyperglycemia. If the CGM continues to malfunction, the situation may get worse and immediate medical intervention may be required.
Now, there may be many contributing factors responsible for the CGM device malfunction. However, the CGM device malfunction is only a trigger event in this scenario, not the hazardous situation. This is a frequent point of confusion during risk analysis. Typically, a fault tree analysis (FTA) or a failure mode effects analysis (FMEA) technique is used to identify all potential faults, failures, and failure modes of a device and its constituent parts or components. However, a common mistake is to confuse them with a hazardous situation within the context of ISO 14971. The result is that the probability of a specific failure, failure mode, or fault is confused with the probability of the occurrence of a hazardous situation, leading to errors in estimating the risk of harm as required by ISO 14971.
As we discussed in Part 1, a fault may not always lead to a failure, and a failure may not always lead to harm. Engineering analysis, using FTA, FMEA, or another technique, should therefore focus only on the probability of failure and not on the probability of hazardous situations and/or harm. These are two fundamentally different concepts. In other words, engineering analysis is necessary for analyzing the risk of harm within the context of ISO 14971, but it is not sufficient.
A second point of common confusion is that a hazardous situation always leads to harm. This is often the underlying assumption when risk analysis is limited to identifying the trigger points arising from faults, failures, and failure modes. However, for the user, property, or environment to experience harm, exposure to one or more hazards is required. A hazardous situation provides such an exposure, but there is still a finite probability that harm may not occur. Figure C1 Annex C of ISO 14971:2019 illustrates the probability of harm (P) to a product of the probability of a hazardous situation occurring (P1) and the probability of a hazardous situation leading to harm (P2).
Therefore, understanding the term “hazardous situation” and how it links to trigger events and sequence of events is critical to correctly performing risk analysis. Watch this video for a deeper analysis of this key concept and share your questions or comments in the Comments section below.
Naveen Agarwal began his consulting practice in 2017, with the goal of helping medical companies build safe products through quality systems that are not only compliant to regulatory requirements but also focused on the needs of patients and physicians. He has 20 years of industry experience in leadership roles ranging from R&D to product quality and business analytics. As a result, he has a broad and deep expertise in all of the core functions involved in the lifecycle of medical products. His consulting practice focuses on problem-solving in the areas of risk management, quality systems, customer experience, and quality culture. You can view other videos by Agarwal on his YouTube channel, email him at Naveen.Agarwal@ExeedQM.com, and connect with him on LinkedIn.