FDA Issues Draft Guidance on Human Factors and Usability Engineering to Optimize Medical Device Design

  • By: Staff Editor
  • Date: November 11, 2011
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The FDA issued new draft guidance on using human factors and usability engineering to optimize medical device design.

In the guidance document, the FDA states that the intent of the document is to “improve the quality of the device user interface such that errors that occur during use of the device are either eliminated or reduced.”
The guidance applies to medical device manufacturers, especially when they perform human factors testing for a device.
To ensure that their design controls are functioning properly, medical device manufacturers have to conduct a risk analysis that includes risks associated with device use.
Human factors testing should be conducted on the device if:
  • The risks analysis results show that there might be a moderate to high risk of use error or
  • If a manufacturer is modifying a marketed device due to use error as a CAPA.
The FDA can also request human factors tests if:
  1. Submission of human factors information is required (for example, as a special control);
  2. Submission of human factors information is recommended in a specific guidance for a device type and the manufacturer cannot justify forgoing such testing; or
  3. On a for-cause basis if it is the least burdensome method to address FDA’s concerns regarding human factors issues.
What is a user interface?
The guidance defines user interfaces as:
  • All components of a device with which the user interacts, such as controls and displays (i.e., those parts of the device that users see, touch, and hear).
  • Including the device labeling, which includes package labels, any instructions for use in user manuals, package inserts, instructions on the device itself, and any accompanying informational materials.
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Summary of Recommendations
Use-related hazards
The guidance states that in order to identify use-related hazards pertaining to medical devices, it is important to understand how a device will be used. Human Factors Engineering (HFE) and Usability Engineering (UE) are the two methods that can be used to understand how people interact with technology.
HFE and UE considerations with respect to medical devices cover the following areas of the device-user relationship:
  1. Device Users
  2. Device Use Environments
  3. Device User Interfaces
The draft guidance outlines the following use-related hazards:
  • Device use requires physical, perceptual, or cognitive abilities that exceed the abilities of the user;
  • The use environment affects operation of the device and this effect is not recognized or understood by the user;
  • The particular use environment impairs the user’s physical, perceptual, or cognitive capabilities when using the device to an extent that negatively affects the user’s interactions with the device;
  • Device use is inconsistent with user’s expectations or intuition about device operation;
  • Devices are used in ways that were not anticipated; or
  • Devices are used in ways that were anticipated but inappropriate and for which adequate controls were not applied.
Conducting HFE/UE analysis
According to the Guidance and ISO 14971, Medical devices – Application of risk management to medical devices, the following three critical steps are necessary to perform successful HFE/UE analysis:
  • Identify anticipated use-related hazards and unanticipated use-related hazards, and determine how hazardous use situations occur;
  • Develop and apply strategies to mitigate or control use-related hazards; and
  • Demonstrate safe and effective device use through human factors validation testing.
The following factors play an important role in HFE/UE analysis, helping manufacturers identify device aspects with potential use-related hazards and the guidance details the role of each:
  • Device users
    • Identification of the end-users of the device (e.g., patient, family member, physician, nurse, professional caregiver)
    • The level of training users will have and/or receive
    • User characteristics (e.g., functional capabilities, attitudes and behaviors) that could impact the safe and effective use of the device
    • Ways in which users might use the device that could cause harm
  • Device use environment
    • Hospital, surgical suite, home, emergency use, public use, etc.
    • Special environments (e.g., emergency transport, mass casualty event, sterile isolation, hospital intensive care unit)
    • Interoperability with other devices
  • Device user interface
    • E.g., functions, capabilities, features, maintenance requirements
    • Indicated uses
Methods for identifying, evaluating and understanding use-related hazards
The FDA guidance documents details two separate approaches to identify, evaluate and understand use-related hazards:
  • Analytical approaches
  • Formative evaluations
Analytical approaches
Analytical approaches involve description and systematic decomposition and analysis of device use. These approaches can be used early in device development processes to identify specific tasks or scenarios, including specific user-device interactions, relevant for assessing inadvertent use errors that could possibly cause harm.
Analytical approaches are useful in identifying and resolving use-related hazards that occur infrequently or are too dangerous to study in an evaluation involving simulated uses.
Analytical approaches include:
  • Analysis of the expected use of new devices and of available information about the use of similar devices; and
  • Employment of methods that can include contextual inquiry, interview techniques, function and task analysis, and heuristic and expert analyses.
Formative evaluations
Formative evaluations or studies are carried out while the product is in development. They derive information based on user interaction with devices and can include simulated-use testing.
According to the FDA guidance, formative evaluations:
  • Should focus initially on the major issues that preliminary evaluations indicate are most likely to have an impact on use safety and effectiveness and those areas where design options for the user interface are not final
  • Can be expanded to include certain aspects of the use environment or specific sub-groups of users depending on the results of preliminary evaluations
  • Methods should be chosen based on the need for clarification prior to developing final design specifications and based on resources available
The guidance details the following two types of formative evaluations that can be used by medical device manufacturers:
  • Cognitive walk-through:
    • In a cognitive walk-through, a user or small group of users are guided through a structured process of using a device, which may be represented as a simple mock-up or early-stage prototype.
    • Participants are questioned and encouraged to provide feedback on difficulties they notice while using the device.
    • Evaluators can collect subjective information from participants about their thought processes, mental models, and perceived workload when using the device.
  • Simulated Use Testing:
    • Simulated use testing, (also called usability testing and, occasionally, user testing) involves systematic collection of data from users (participants) using a device (or device component or system) in realistic situations.
    • Data are obtained in a variety of ways, including subjective user feedback, manual and automated measures of user performance, and direct observation.
Mitigating and controlling use-related hazards
The guidance details the following strategies to control use-related hazards:
  • Modify the device design to remove a hazard or reduce its consequences
  • Make the user interface, including its operating logic, error tolerant
  • Alert users to the hazard
  • Develop written procedures and training for safe operation
The guidance also stresses the need for design verification testing and human factors validation testing through simulated use.
Appendix A of the guidance gives the format of the HFE/UE report that medical device manufacturers can use to report the findings of their analyses.
Additional Resources
Read the FDA Draft Guidance on Human Factors and Usability Engineering to Optimize Medical Device Design in full


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