When medical devices are user-friendly there is a higher probability for users to continue using the device for clinical or personal purposes and highly recommend the device to others. Hence, careful design of the device-user interface needs to be conducted to ensure that use errors are eliminated or reduced. The reduction of use errors severity or occurrence will improve the quality of medical treatment the device offers to the target population. FDA recognizes this Human Factor (HF) as an important attribute while conducting the risk-benefit analysis of a medical device. This article outlines the process a medical device manufacturer should follow to help categorize the device and provide relevant information to the FDA based on how the device is categorized. For instance, if a manufacturer wishes to release a new portable fingertip oximeter which has been verified and compared with a predicate device successfully, he/she may justify how there are no new critical tasks the device performs and skip the Human Factors assessment test. However, if the device claims to perform new critical tasks, then the manufacturer needs to provide evidence of the verification and validation testing phase to convince the FDA that addition of the new critical task does not cause significant harm to the user.
Human Factors Submission Categorization Criteria
As a medical device manufacturer you would wish to know during the early stages of your product development about which classification your device would fall into in relation to Human Factors Categorization criteria. For this purpose, a brief outline of the classification of the product will help in estimating the time and budget required to develop the product. Categorization of the product is based on the following Decision Points:
Decision Point A: Is it a modification to an existing device?
If your device is completely new the answer to this question would be a “No.” However, on the other hand, if it is like another of your own device or a similar device which has already received authorization by the FDA to release into the market the answer to this would be a “Yes.” In this case, the human factors information of the similar device can be leveraged for use in the current device.
Decision Point B: Is there change in the following factors: –
- User Interface.
- Intended device users.
- Intended device uses.
- Intended use environment(s).
- Training or Labeling.
The above list of factors is useful to assess if the changes in the modified devices would affect any of the human factors involved. The device would fall into the HF Submission Category 1 if the answer is “No” but if the answer is “Yes” then you will need to proceed to Decision Point C.
From the perspective of the use-related risk analysis you need to answer “Yes” to any one of the following questions:
- Whether the device performs critical tasks (for new devices) or
- Whether new critical tasks are introduced (for modified devices) or
- Whether the existing critical tasks are impacted due to the modifications made (for modified devices)
The easiest way to answer the above questions is to conduct the Use Failure Modes and Effects Analysis (uFMEA) and other methods of use-related risk analysis of the final finished product. A holistic assessment of all the critical tasks is important to identify whether the impact occurs upstream or downstream from the device-user interface. The changes in the device-user interface may influence the cognitive and/or visual perception or the physical interaction between the user and the device. If there are no new critical tasks performed by the device or no major impact in a modified device, the HF Submission Category would be 2.
However, if the answer is “Yes” then the HF Submission Category would be 3.
Information required for each HF Submission Category
Once you have successfully categorized the device using the above mentioned criteria, you need to know the information needed to be submitted to the FDA:
HF Submission Category 1:
A brief summary (including conclusion) of the HF evaluation. It should also include a statement explaining how the modifications do not affect HF considerations of the current device. The HF engineering of the similar device can be leveraged to prepare this evaluation.
HF Submission Category 2:
A clear rationale why you believe there are no critical tasks (new devices) or no new critical tasks/changes made (modified devices). This would be similar to the reason why the device was placed in Category 2 in the 1st place. Apart from the summary and conclusion, a clear description of the intended device users, uses, use environment and training should be provided in addition to a description of the device-user interface and summary of known use problems.
HF Submission Category 3:
The information required for this category should be the most detailed such as the submission of a human factors report that includes the preliminary activities and results of the validation testing that addresses the critical task(s) of the new device or the new critical tasks/existing critical task(s) which impact change in the device. In addition, a use-related risk analysis containing the identification and description of critical tasks as well as the hazard and risks associated with the risk of use of the device. On occasions in which the existing risk control measures of modified devices remain acceptable, you should provide the rationale within the HF information.
Content of HF Information
If you are worried about what content should be included in the HF information, the following list is a useful guide to draft the HF information content:
Section 1: Conclusion and high-level summary
This includes a statement declaring that your team has designed the device user interface adequately for the intended users, uses and use environments. In the case of the introduction of new critical tasks or impactful modification of the device, further human factors testing should be introduced. Also, a high-level summary of the HF engineering assessment should be provided. This section would also address the residual use-related risks identified after human factors validation testing and describe why risk mitigation is not practical.
Section 2: Descriptions of intended device users, uses, use environments, and training.
This section would contain a more detailed description of the topics mentioned in section 1, namely the intended user population, device’s intended use, device’s operational context of use, intended use environments, and any training users would receive.
Section 3: Description of device-user interface.
This section would include illustrations or sketches of the device and the user interface depicting the individual components the user will interact with, for example, the alarm speakers, controls, keypads, etc. Other important information, such as the labeling content, overview of the operational sequence and comparison with the subject device should be included in this section.
Section 4: Summary of known use problems
For modified devices, the identified use problems should be described in this section. If there are no known use problems, that should be stated in this section.
Section 5: Summary of preliminary analyses and evaluations
For modified devices, this section would include the key results of the preliminary analysis and evaluation and key findings of the HF validation test.
Section 6: Analysis of hazards and risks associated with use of the device.
The portion of the risk analysis which addresses the use-related hazards throughout the device design process would be included in this section. A tabular format comparing the risks of the existing and new devices is one clear way of stating the risks related to modified devices.
Section 7: Identification and description of critical tasks
How the critical tasks were identified should be described in this section. The severity level of the potential harm resulting from the failure of the critical task performance and the reference to the applicable standard should be included in this section. If the critical task does not require HF validation, then the rationale explaining this should be included as well.
Section 8: Details of HF validation testing of final design
This section would include the summary of the HF validation activities conducted. All use errors and problems should be described in this section along with the real-world use and design modifications of the user interface to mitigate the risks. The test protocol and a sample of the results must be provided in this section. If the risks are unacceptable a reevaluation of the risk control and mitigation measures should be identified.
How RookQS can help
RookQS has the expertise to leverage their knowledge dealing with past clients to assess the human factors attributes of medical devices. We are not only aware of the FDA perspective while assessing the risk-benefit of medical devices, but also the challenges manufacturers face during the device development process. Given our technical knowledge in the field of medical devices, we will be able to provide practical solutions and guidance on how best to design and modify the product the manufacturer intends to release to the market. In the validation testing phase, RookQS is knowledgeable regarding how best to design the test protocols and present the information to the FDA in a convincing manner.