Crash Course on URRAs
As human factors specialists in the medical device industry, our world is centered around mitigating use-related risks. Ultimately we hope to design a device that is safe and effective to use. An important aspect of this process is developing and maintaining a cohesive use-related risk analysis. We’ve written this blog to outline some steps to help medical device manufacturers strategize their Use-Related Risk Analysis, more commonly referred to as a URRA, to keep the process as simple and straightforward as possible.
Why are urra’s important?
First, it’s important to understand why this effort is necessary. International and jurisdictional standards directly speak to the management of use-related risks and hazards. The FDA guidance details the analysis of use-related hazards and their incorporation into the risk management process. IEC 62366 indicates the identification of known foreseeable hazards and hazardous situations related to use must be conducted in accordance with the international standard for risk management of medical devices (ISO 14971). Both references highlight the importance of conducting the use-related risk analysis alongside the other analysis efforts as part of the overall risk management program for a medical device.
More importantly, the steps necessary to develop and maintain a URRA facilitate and are some of the fundamental parts of the overall human factors and usability engineering process. Developing a cohesive URRA ensures that as medical device manufacturers, we are taking the measures necessary to develop a safe, usable product.
Start with a task analysis
Now where do we start? We first define what tasks and interactions are required for correct use. A task analysis is an effective (and recommended) mechanism to detail the tasks involved with the use of a product. A task analysis breaks down a higher-level task (or scenario) into a sequence of discrete steps. For simpler devices/systems, there may be only one (1) high-level task and subsequent sub-tasks. In other circumstances, it may be necessary to define several tasks and their correlating sub-tasks. The table below is an example of a task analysis for an auto-injector.
The task analysis is the foundation of the URRA. As such, its tasks and sub-tasks are defined clearly and maintained as the product matures. It’s expected that interactions will change as the design is refined and the task analysis should be maintained accordingly.
Perception, cognition, & action (PCA)
Once we have our tasks specified, we can analyze them and identify use-related hazards. A mechanism to facilitate this step is to use Perception-Cognition-Action analysis, or PCA Analysis. PCA identifies the Perception, Cognition and Action the user must complete/consider for each step.
We can ask ourselves the following questions to work through the PCA for each task, when determining what has to happen for the user to complete the task successfully:
The table below is a continuation of our previous example, now implementing PCA analysis:
Potential use errors
As we detail the perception, cognition, and action needs for each task, we can consider possible use errors if the user does not perceive, understand, or do something correctly. The next step of the process is to define these use errors, so we introduce our use error column to our table. For simplicity, the table below considers 2 of our previously defined tasks:
define hazardous situations and harms
The next step is to determine what hazardous situations could be presented by each use error. The determination of these hazardous situations is associated with a level of harm (severity of harm) to the patient and/or user and drives the associated risk mitigations and control measures. The author of the URRA should consider “What could reasonably happen to the patient or user if this use error occurs?” The range of outcomes could vary widely, from no harm at all to a catastrophic injury or death.
Tasks that are determined to be associated with a level of harm considered “serious” or higher are categorized as critical tasks. Often, severities of harm are associated with numerical ratings, such as a scale from 1-5. Manufacturers establish a threshold, at or above which, tasks are determined to be “critical” or “non-critical”.
The approach outlined in this blog is a suggested strategy intended to build a cohesive and proactive URRA. One of the most helpful aspects of this approach is that use errors are generated from tasks specifically, rather than brainstormed without any, or with little context. Building out the narrative of correct use prior to brainstorming use errors provides some structure needed to help envision ‘reasonably foreseeable’ misuse and use errors. If done correctly, the URRA serves not only as a key element of the final usability validation, but also as a design tool that the team can use throughout the development process to assess and improve upon user interactions, and ultimately a medical device’s safety and usability.