Medical Device Human Factors: Designing Safe Medical Devices

Medical Device Human Factors: Designing Safe and Effective Medical Devices

The FDA defines Human Factors or Usability Engineering as the application of knowledge about human behavior, abilities, limitations, and other characteristics of medical device users to the design of medical devices including mechanical and software driven user interfaces, systems, tasks, user documentation, and user training to enhance and demonstrate safe and effective use. The term Human Factors Engineering and Usability Engineering can be used synonymously.

Learn more about Human Factors/Usability Engineering and how Improvita can guide you through the process below.

The primary purpose of incorporating Human Factors/Usability Engineering process into developing medical devices, software as medical devices, and combination products is to reduce use-related hazards and risks so that the end users can use the product safely and effectively. More details on specific beneficial outcomes of applying Human Factors/Usability Engineering to medical devices can be found under Human Factors and Medical Devices on the FDA website.

Application of Human Factors/Usability Engineering to Medical Devices

The Applying Human Factors and Usability Engineering to Medical Devices FDA guidance document should be followed when incorporating the Human Factors/Usability Engineering process into developing medical devices intended to be marketed in the USA. The FDA also recognizes the IEC 62366 (Medical devices – Application of usability engineering to medical devices) standard related to application of Human Factors/Usability Engineering. The IEC 62366 standard is also recognized by other countries such as the UK, European Union countries, and Canada.

Device Users, Use Environment and User Interface

At the beginning of the Human Factors/Usability Engineering process, it is important to document the following key aspects of the medical device as they are important for identifying use related risks and testing the device to ensure safety and effectiveness from the usability perspective:

  • Device Users
  • Device Use Environment
  • Device User Interface

Device Users

Device users are the intended users of the medical device and they should be able to use the device without making user errors that compromise medical care or patient or use safety. Examples of device users include patients, nurses, healthcare providers (HCPs) and caregivers. The ability of a user to operate the medical device is dependent on the user’s personal characteristics such as health status, education, cognitive abilities, knowledge and experience with similar types of devices. Therefore, it is critical to understand the device user population as use risks can vary between different user groups.

Device Use Environment

The device use environment is the environment and condition in which a medical device is used. Examples include a bathroom or kitchen, an examination room, an operating room, low or high lighting condition, and a room with cluttered equipment. Risks associated with use environment varies depending on the type of environment.

Device User Interface

According to the FDA, a device user interface includes all points of interaction between the user and the device including all elements of the device. Examples include graphical user interfaces of device software systems, size of device, control buttons on a device, handles, packaging and Instructions For Use (IFU). Use related risks are dependent on the complexity of the user interface. The FDA recognizes that improving the device user interface is an effective strategy to reduce or eliminate use-related hazards. Hence, a well-designed medical device user interface can reduce the chances of use errors and harming end users or use environment.

Identifying Critical Tasks

After the above context of use has been defined, it is important to comprehensively identify each user task associated with the device and to discern which are critical tasks.

For medical devices, the FDA defines a critical task as a task that if performed incorrectly or not performed at all would or could cause serious harm. When determining a critical task for a combination product, the FDA defines harm to include compromised medical care. Various tools can be used by the manufacturer to identify critical tasks and mitigate the risks associated with those tasks such as a task analysis, Failure Mode and Effects Analysis (FMEA), and a Fault Tree Analysis (FTA). Detailed information on the tools and more examples can be found in the Applying Human Factors and Usability Engineering to Medical Devices guidance document. This process of evaluating user tasks and distinguishing the critical tasks should start early in the design phase.

Known Use Related Problems

During the development of a medical device, it is beneficial to identify known use-related problems associated with similar devices with regards to device use, user interface and user interactions. Manufacturers can use this information to eliminate or mitigate risks early in the design phase by learning from the issues encountered by other manufacturers. This process helps identify risks that may be applicable to the device under development.

Known use-related problems can be identified using various methods such as reviewing customer complaint files or using FDA databases like the Manufacturer and User Facility Device Experience (MAUDE) database and the Medical Product Safety Network (MedSun) database.

If the known use-related problems are applicable to the device under development, the risks should be incorporated in the risk management process for the medical device.

Formative Evaluation

A Formative Evaluation is a process of testing a medical device’s user interface early in the design and development process to collect data to refine a medical device’s design with respect to safe use if modifications are necessary. The evaluation is important for identifying potential use risks that may not have been identified through the known use-related problems analysis or early risk assessment of the medical device. A Formative Evaluation can also help identify new critical tasks, evaluate the effectiveness of implemented risk controls related to use errors based on the risk management process, and inform content and structure for Human Factors Validation Testing.

Various methods can be used to conduct a Human Factors Formative Evaluation such as a cognitive walk through and simulated use testing. Refer to the Applying Human Factors and Usability Engineering to Medical Devices guidance document for details on Formative Evaluation methods.

According to the FDA, a Formative Evaluation protocol typically specifies the following:

  • Purpose of the evaluation
  • Portion of the user interface to be evaluated
  • Tasks and use scenarios
  • Participants
  • Data collection and analysis method
  • How evaluation results will be used

Risk Management

Risk Management is a critical part of developing medical devices, and Human Factors/Usability Engineering plays an integral role in that process. All use-related risks identified based on the preliminary analysis and evaluations (i.e., identifying critical tasks, known use-related problem analysis, and Formative Evaluations) should feed into the manufacturer’s risk management process following the ISO 14971 standard. The Human Factors process within risk management evaluates the use related risks and aims to eliminate the hazards associated with those risks or reduce them to the lowest possible level.

Human Factors Validation Testing

Human Factors Validation Testing demonstrates that the medical device can be used by the intended users without serious use errors or problems. The FDA recommends the following during Validation Testing:

  • Test participants represent the intended (actual) users of the device
  • All critical tasks are performed during the test
  • The user interface under test is representative of the final design
  • The test conditions are sufficiently realistic to represent actual conditions of use

The study should be designed to allow participant interactions with the device in an authentic manner. Generally, testing is conducted in a simulated use environment but, when necessary, can be conducted under conditions of actual use or as part of a clinical study.

A robust test protocol is required, including participant inclusion/exclusion criteria to screen for the intended use population, use scenarios, data collection and analysis plan. More details on developing a Human Factors Validation Test can be found in the Applying Human Factors and Usability Engineering to Medical Devices guidance document. The FDA recommends submitting a protocol draft for agency review to ensure alignment in test approach prior to study execution.

Human Factors/Usability Engineering Report

After the Human Factors/Usability Engineering activities are completed, a summary report should be written to provide an account of preliminary analyses, Formative Evaluations, Human Factors Validation Test results, and final conclusions drawn. For details on the structure of a Human Factors/Usability Engineering report, refer to Appendix A of the Applying Human Factors and Usability Engineering to Medical Devices guidance document.

Why Choose Improvita for Medical Device Human Factors/Usability Engineering Consulting?

By choosing Improvita’s medical device Human Factors/Usability Engineering consulting services, medical device, SaMD and combination product manufacturers can benefit from our extensive experience and knowledge of conducting Human Factors/Usability Engineering activities which includes but not limited to risk analysis, task analysis, Formative Evaluations, Validation Testing, and protocol and report writing. We support medical device development with the user needs front and center. We have a proven history of helping clients obtain FDA approval of their products by supporting risk identification and mitigation strategies elucidated through the Human Factors/Usability Engineering process.

To learn more about Improvita’s Human Factors/Usability Engineering consulting services, contact us to discuss your specific needs.