If there’s no use risk, then no problem! That's what most directives indicate, however, users are unpredictable.
If a user performs a tasks incorrectly or fails to perform a task, could it cause serious harm? This is the question the CDRH asks. As a result, CDRH requires that human factors engineering data be submitted with all PMA or 510K submissions.
If you are applying for submissions this is important! The fact is that the application of human factors takes planning, time and, if not done correctly, expensive to complete. If the device in development is following an existing device, it’s easy to ignore. However, FDA Human Factors Guidance (2016) and IEC 62366 are very clear in their expectations that human factors and usability engineering processes are required to assure device use is safe and effective for users, intended uses and use environments.
It further requires that human factors processes are part of a robust design control subsystem. If an application is submitted without a human factors dossier, expect a challenging response. The only caveat being an application for a derivative device with modifications on non-functional aspects which do not affect the user interface or previous human factors as submitted.
The need for integrating human factors processes is only increasing within the global market. This is evident by MHRA, the UK medicines and medical devices regulator, publication titled Human Factors and Usability Engineering of Medical devices and Drug-Device combination Products, (Sept 2017) wherein there is no avoiding usability engineering: All classes of medical devices and device-drug combination products should include human factors processes. This publication includes essential requirements in the Medical Device Regulation (MDR) and In-Virto Diagnostic medical Devices Regulation (IVDR) that mandate usability activities. The good news is that all of the human factors guidance documents, including the MHRA guidance, are in alignment and spell out clear expectations.
The application of human factors does not necessarily need to be expensive, rather it must be thorough and concise. Utilizing published standards such as ANSI/AAMI HE75 as a basic application of human factors can be readily done by an experienced and knowledgable engineering team. In fact, locating the standards is made easier now that the MHRA document provides a helpful list of published regulations, standards and agency guidance’s that it recommends be utilized in development. This is a good place to start when no human factors have been completed. Look for ways in which the device design meets these published industry standards and record them as part of the overall human factors effort. Another benchtop human factors methodology can include conducting a heuristic analysis or expert review. This methodology, is intended to uncover areas of improvement for optimum usability and assesses user interactions at all touch points.
The Application of Human Factors Starts with Design and good design starts with knowledge of the user (their capabilities, education, training and disciplinary bias) along with a clear understanding of the use context (environmental conditions and circumstances which impact device use). Often, medical device companies have a key users or clinical advisors that they have partnered with in order to advance the design, this is another opportunity to gain valuable insights regarding overall usability during the design process. These user interactions and design evaluations should be documented and presented as historic reference to the application of human factors in a final submission for agency approval.
Ultimately, use-related hazards and risks must be identified through all preliminary analyses and to the extent possible designed out, reduced in likelihood or in the severity of harm (FDA 2016). Design modifications to the user interface, making it easier for the user to do the right task and harder for them to do the wrong one, is the best approach in demonstrating the application of human factors. Where this is not possible, the use of alarms, alerts, labeling, training and the instructions for use (IFU) may be effective.
Regardless of your risk management strategy, human factors validation (or summative usability test) is required and intended to demonstrate that the device can be used by the user without serious use errors for the intended uses and use context/conditions. For this test, the FDA (2016) has provided clear guidance regarding the number of test participants, the expected conditions, as well as the content regarding the tasks and use scenarios to be used within each validation study. Often overlooked is the requirement of IFU’s, the participant training, training decay allowance as well as the incorporation of subjective assessment of any use difficulties by participants constructed with open ended, neutrally worded questions. The analysis of human factors data needs to be qualitative in nature including discussion on root causes. If a device proves to have considerable usability challenges, especially in regards to critical tasks or those with tasks with greatest risks associated, the design should be modified and re-tested. Once modified, only those aspects of the use interface which were changed need to be re-assessed in order to assure risks are managed to acceptable levels. Any further residual risks should be analyzed and may yet require design modifications, however it is impossible to design out all levels of risk.
Documentation of HFE/UE testing, design optimization processes ultimately provides evidence that the needs of the intended user were considered throughout the design and development process. The FDA requires a summary of these activities as part of a human factors dossier which is described with the guidance with more clarity in the following sections:
- Description of intended users, uses, use environments and training
- Description of device user interface
- Summary of known use problems
- Analysis of hazards and risks associated with use of the device
- Summary of preliminary analyses and evaluations
- Description and categorization of critical tasks
- Details of human factors validation testing
Regardless of the type of medical device, when human factors methods are used throughout the development process, not only are agency requirements met, but ultimately user satisfaction increases.
At the end of the day, the goal of all medical devices are to improve life. With these new directives, its clear the FDA wants medical device manufactures to stay consistent, reduce risk and improve the lives of all users. Use human factors is required, why not use it to your benefit?