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A Step-by-Step Guide to Usability Engineering in Medical Device Development

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IEC 623661 Essentials: Elevating User Safety in Medical Devices

Usability engineering, also known as human factors engineering, plays an essential role in minimizing use-related risks associated with medical devices. The standard IEC 62366-1 offers valuable guidelines for integrating this discipline into the development process.

Senior Human Factors Specialist, Maude Leclerc-De Guire, and Quality Assurance Manager, Jean-Yves Pairet, recently shared their expertise in a webinar hosted in partnership with Greenlight Guru.

After reviewing the applicable regulatory framework, they detailed the key activities involved in usability engineering at every stage of development, from identifying user needs to conducting validation testing.

Key Activities Throughout the Medical Device Development Process

Integrating usability and human factors engineering into the medical device development process is crucial for ensuring that products are safe and effective.

The development process consists of five key phases:

1. Planning Phase

A usability plan is developed, outlining the primary activities for each phase of development.

2. Definition Phase

Key user needs, potential usability errors, and the use environment are identified. These insights are then translated into design inputs related to the user interface.

3. Design Phase

User feedback and the results from formative evaluations are utilized in iterative design and test cycles to refine the product.

4. Verification Phase

Activities are conducted to ensure that the user interface design strictly complies with all specified requirements.

5. Validation Phase

Activities are conducted to ensure that the user interface design strictly complies with all specified requirements.
A risk-in-use approach is maintained throughout these phases to ensure that all design decisions contribute to minimizing potential risks associated with using the device.

1. Planning Phase

First and foremost, the human factors team draws up the usability plan, which is integrated into the design and development plan. This document details the main human factors activities, such as usability specifications, usability risk analysis, user interface specifications, as well as formative and summative evaluations.

It also defines the roles and responsibilities of all team members involved, including close collaboration between human factors specialists, user interface (UI) designers, industrial designers, and the quality assurance team.

2. Definition Phase

User Needs Definition

Defining user needs is a fundamental step in the development of any medical device. This crucial phase guides all subsequent development activities and begins with the establishment of clear use specifications.

To correctly define these specifications, three main elements must be taken into account:

Several methods are used to draft these use specifications:

 

  • Market research, which includes analysis of competitors’ devices and documentation.
  • User research, involving direct interaction with potential users of the device.
  • Field observations and interview sessions with subject matter experts to gather information on the actual context of use.
Factors such as users’ physical strength, sensory capabilities (including vision and hearing), cognitive abilities (such as literacy) and emotional states (for example, anxiety) must all be considered.

Concurrently with the definition of use specifications, the Human Factors (HF) and Quality Assurance (QA) teams begin to collect and analyze existing information on known use risks. To accomplish this, they use databases such as MAUDE and GUDID, as well as internal company databases that contain complaints and CAPA reports. This activity forms the foundation for the use-related risks analysis.

Design Inputs Definition

While user needs can be vague and qualitative, design inputs should be more detailed, specific and quantitative, as they directly influence the user interface design.

To ensure this stage is executed effectively, the Human Factors team must collaborate with the development team.
These are the activities required to define design inputs:
1. Task Analysis
The Human Factors team breaks down each user interaction with the medical device into individual tasks to gain a clear understanding of the user journey. This analysis is crucial in identifying potential errors and usage scenarios.

2. Use-Related Risk Analysis (URRA)

This process incorporates previously identified risks and lessons learned from task analysis. Dangerous situations and potential harm are defined for each risk. It should be noted that risk level estimation focuses on severity rather than probability.
3. Risk Control
Adopting methods to mitigate the risks identified by URRA is essential. These methods should be integrated into the design elements to ensure safety and efficacy.

3. Design Phase

Reducing use-related risks is an essential objective in the design of medical devices. To achieve this, the user interface design must be iterative and include rigorous formative evaluations.

Formative Evaluations

Formative evaluations are a cornerstone in the process of minimizing use-related risks in medical device development. The primary objective of these evaluations is to iteratively refine the product’s user interface.

The guiding principle here is simple: when in doubt, test!

During these evaluations, users interact with the device (or its proof-of-concept, prototype or mock-up) in simulated use environments or under real-life conditions.
Here are three tips for successful evaluations:
1. Iterate, iterate, iterate
A single formative evaluation is rarely enough to identify all potential problems and areas for improvement. Several iterations enable us to progressively refine the system by addressing details that had not emerged in previous cycles.
2. Involve participants with a user-centered approach
The success of a formative evaluation depends on the perspectives of those involved. By focusing on the user, feedback will focus on enhancing usability and satisfaction with the device.
3. Going beyond use-related risk identification
Evaluating the user experience as a whole is just as important. This approach provides a better understanding of how the device operates in real-life scenarios, encompassing all aspects of user interaction.

To gain meaningful insights for improving the medical device, the optimal number of participants is 5 to 8 per evaluation.

4. Verification Phase

In the medical device development process, the verification phase ensures that the user interface strictly complies with all design requirements.

Here are some of the methods you can use:
The aim of verification is not to make major changes to the device. Rather, this phase ensures that the final product meets all predefined requirements.

It’s important to differentiate between formative evaluations and verification activities. Formative evaluations are iterative tests conducted during the design phase to refine the user interface. Verification, on the other hand, occurs once the device design is finalized.

Therefore, formative evaluations help identify issues and implement changes early in the development cycle, whereas verification is performed on the final design, which will undergo little to no further changes. It’s worth noting that verification should be planned early in the design phase to ensure smoother execution.

5. Validation Testing

The validation phase includes a critical activity within the medical device development process: the summative evaluation.

This phase validates the user interface, focusing specifically on safety aspects related to use. Whether or not it is carried out depends on the regulatory strategy and product class.

Summative Evaluation

More specifically, summative evaluation verifies the effectiveness of all risk control measures. Its aim is to demonstrate that the device not only meets the required safety standards, but also functions effectively in the hands of users. To achieve this, the summative evaluation must accurately reflect actual use conditions.

This phase validates the user interface, focusing specifically on safety aspects related to use. It may or may not be conducted, depending on the regulatory strategy and the product class.

Here are a few points to consider when drawing up a thorough evaluation protocol:
After comprehensive testing during the summative evaluation, the medical device will be ready for market, ensuring compliance with usability principles and guaranteeing user safety.

The Benefits of Integrating Usability Engineering into Medical Device Development

Considering human factors and usability in medical device development not only helps to meet regulatory requirements but also reduces errors and use-related risks.

Here are just a few of the additional benefits:

Integrating usability and human factors engineering into medical device development is a rigorous process that improves overall product quality. This approach ensures that the medical device is more user-friendly, easier to operate, and more ergonomic.

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Written by
Caroline

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