The Human Factor - Preparing Your Device for Usability Testing

July 22, 2021

When it comes to usability studies, the focus should be on effectively preparing the medical device for use in humans. Whether a Sponsor is conducting formative testing or validation testing, the "human factor" is the overriding concern; and, incorporating human factors data early on, and throughout the design process, can reduce the need for costly modifications or updates later in the approval process. Read about this in our post, or contact us for additional information.

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The Human Factor

Essentially, the human factor is how the user of a medical device interacts with that device and the risks that are introduced because of the human element. To assess and mitigate or eliminate these risks, the FDA has recommended that Sponsors design and conduct usability tests. The purpose of these tests is to test drive their product in real-life circumstances, consider feedback from users, and make any necessary changes to reduce patient adverse events and medication errors due to use-related errors. This is often called "human factors engineering."

According to the Agency, to understand user/device interactions, it’s important to understand the way people perceive information from the medical device, the way they interpret that information and make decisions about what to do, and the way they manipulate the device, its components, and/or its controls. It is also important to understand the ways the device receives input from the user and then responds and provides feedback to the user about the effects of their actions.

Using these understandings, Sponsors can develop a medical device with a range of beneficial attributes, including:

  • Easier-to-use devices
  • Safer connections between device components and accessories (e.g., power cords, leads, tubing, cartridges)
  • Easier-to-read controls and displays
  • Better user understanding of the device's status and operation
  • Better user understanding of a patient's current medical condition
  • More effective alarm signals
  • Easier device maintenance and repair
  • Reduced user reliance on user manuals
  • Reduced need for user training and retraining
  • Reduced risk of use error
  • Reduced risk of adverse events
  • Reduced risk of product recalls

Preparing Your Device for Usability Testing

Human Factors Formative Testing

Human factors formative testing assesses the user interface or user interactions with the user interface to identify the interface’s strengths and weaknesses, and to identify potential use errors that would or could result in harm to the patient or user.

This test can be conducted at one or more stages of the development process. Not only do the results inform the design of the device, but they also assess the effectiveness of measures implemented to reduce or eliminate use-related hazards or potential use errors. Design modifications should be implemented and then evaluated for adequacy during this phase of development in an iterative fashion until the device is ready for human factors validation testing.

Human Factors Validation Testing

This level of testing is conducted at the end of the device development process to assess user interactions with the device’s user interface to identify use errors that would or could result in serious harm to the patient or user. Validation testing is also used to assess the effectiveness of risk management measures.

According to the FDA, for the device to be considered optimized for safety and effectiveness, the human factors validation testing should be sufficiently sensitive to capture use-related problems resulting from user interface design inadequacies, whether or not the users are aware of having made use errors. Further, the realism and completeness of the testing should support generalization of the results to demonstrate the device’s use safety and effectiveness in actual use.

The results of this testing should facilitate analysis of the root causes of use error or problems found during testing. The FDA encourages Sponsors to submit a draft of the human factors validation testing protocol prior to conducting the test so that the Agency can ensure that the methods the Sponsor plans to use will be acceptable.

Preparing a Medical Device for Testing

The most effective way to prepare a device for usability studies is to employ human factors engineering. This means considering the user at every stage of the medical device design process, then building in design elements that mitigate or eliminate those user-related risks.

This approach is highly effective because design elements are much better at mitigating or eliminating risks than instructions or training. The reality is that not everyone reads or understand instructions, and people are likely to forget their training.

A good example is a pen injector. One of the potential risks could be the unintentional prick of the needle after use. The skin prick is more likely to happen if the needle is protruding from the pen injector after the injection. On the other hand, the unintentional prick is less likely to happen if a design feature is incorporated to automatically retract the needle back into the device after it is used. This design feature eliminates a user-related risk regardless of how the device is labeled or whether the user forgets their training.

Preparing Your Device for Usability Testing: ProPharma Understands Human Factors

Usability studies that take the human factor into consideration are essential for building a robust design control system that mitigates or eliminates the risk of adverse events, medication errors, and use-related errors. The success of a device development program depends on conducting formative and validation tests successfully with an eye toward public health.

It’s very painful when a Sponsor submits a marketing application and is told by the FDA that the human factors validation testing they conducted isn’t good enough. To avoid the time and expense of going back to square one, Sponsors should rely on a resource like ProPharma as early as possible in the device development process.

Our seasoned consultants have experience in identifying regulatory risks associated with human factor elements. Additionally, we have working relationships with testing laboratories that excel in conducting human factor tests. We help Sponsors get it right the first time. Contact us today for help with your usability testing.


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