Since the mapping of hazards, hazardous situations, and harms involves many-to-many relationships, these linear methods often are difficult to implement within the context of ISO 14971.

They address different failures and failure modes in a linear fashion, one at a time. Most of these other methods are suitable for engineering risk analysis to improve product and/or process reliability. There are other analytical tools available, such as failure mode effects analysis (FMEA), fault tree analysis (FTA), hazard and operability study (HAZOP), and hazard analysis and critical control points (HACCP). In this way, a PHA can provide the initial framework for risk assessments to cover both risk analysis and risk evaluation.Īlthough ISO 14971:2019 does not explicitly require that a PHA be used for risk analysis, it is a highly effective method to comply with the requirements of the standard. It may also include an early identification of the POH and S values, whether quantitative or qualitative, to each of the hazard-hazardous situation-harm relationships and a list of potential risk control measures. Annex C in ISO 14971:2019 provides additional examples of the relationships between hazards, sequence of events, hazardous situations, and harms.Ī PHA is a list of hazards, hazardous situations, and harms, formulated by considering materials of construction, components used and their interfaces, use environment, operating principle (chemical, electrical, mechanical, electromagnetic etc.), and other relevant factors. In other words, there are many-to-many relationships between hazards and harms. Keep in mind that one hazard can result in more than one harm and more than one sequence of events can give rise to a hazardous situation. Now, different scenarios (sequences of events) can be outlined that specifically relate to a medical device and its use environment that may lead to such exposure (hazardous situation). In that sense, the analysis considers “association,” rather than “causation.” As an example, it is generally known that localized or systemic infection (harm) may result from exposure to one or more sources of biological contamination (hazard). Notice the term “inductive” it means that this analysis relies upon currently available information, including prior field experience with similar devices. When done right, a PHA is a highly effective way to not only focus your design and development process on safety but also to provide a means to evaluate post-market information in terms of underlying hazards and currently implemented risk measures.Īccording to ISO/TR 24971:2020, the guidance on the application of ISO 14971, a PHA is an “inductive method of analysis with the objective of identifying the hazards, hazardous situations and events that can cause harm for a given activity, facility or system.” 2

In this article, I will address the What, the Why, and the How of a PHA to help you develop and deploy this powerful tool in your product development process. The focus here is not on “what can go wrong?” but rather on “what is the relationship between likely hazards and potential harms?”. It is more of a top-down approach, which helps to build a link between events, whether triggered by a device malfunction or not, and the resulting hazardous situations that may potentially lead to one or more harms. A PHA is a method of analysis to identify hazards and link them to hazardous situations that may lead to harm. This is where a preliminary hazard analysis (PHA) can help. But device failures and failure modes don’t necessarily lead to hazardous situations and harms, and harms can occur even when there is no device malfunction. However, this information is generally not available during early development.Įngineers tend to focus on device failures and failure modes, and their causes and effects, in order to make sure the device “works” reliably. Therefore, in order to estimate risk, we need to assign the values of POH and S to each of the potential harms associated with a particular medical device. Risk is a combination of the probability of a harm (POH) and severity of that harm (S). In practice, this exercise often proves to be challenging, especially during the early phase of design and development, as the link between hazards and potential harms is generally not well understood. 1 The main purpose of this analysis is to identify all applicable hazards and to estimate risks associated with a particular medical device. Risk analysis is a key requirement of ISO 14971:2019, the recently revised International Standard for Risk Management of Medical Devices. By Naveen Agarwal, Ph.D., principal and founder, Creative Analytics Solutions, LLC

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