In the rapidly advancing world of medical devices, ensuring user safety and optimal performance is paramount. This calls for meticulous attention not only to the design of the devices themselves, but also to the instructional materials that accompany them. The efficacy of these instructional materials, whether intended for lay users (e.g., patients and caregivers) or healthcare professionals, plays a vital role in establishing safe and effective interactions between end users and medical devices. This is especially important because these instructional interfaces are typically used when other sources of support are not available to end users.

In this article, we will explore the importance of combining instructional design principles with human factors engineering (HFE) to design instructional materials for medical devices.

Understanding the Regulatory Landscape

Instructional materials for modern medical devices come in various forms, ranging from printed Instructions for Use (IFU) to mobile applications, electronic IFUs and quick reference guides. While the types of instructional interfaces have evolved, the regulatory view remains consistent. According to the FDA’s Final HF Guidance from 2016 and IEC 62366-1 2015 AMD1 2020, instructional materials are considered part of the user interface. This regulatory expectation emphasizes the need to design and develop instructional materials within the Human Factors Engineering (HFE) process to ensure the entire device user interface is safe and effective.

Because of this expectation, there can be significant risks to a human factors (HF) regulatory submission if appropriate care is not taken to design, test and optimize instructional materials along with the device. If issues are found with the instructions late in the HF program, such as in the HF summative or validation study, costs and delays associated with making updates and conducting further HF testing may be incurred. In addition, poorly designed instructions could contribute to improper or incorrect use of a device resulting in harm to a user or patient.

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Too often with medical device design, it is an afterthought to address development of the instructional materials rather than giving it the proper considerations early on as part of the overall design process.

While the necessary approach to developing instructional interfaces for medical devices has its nuances, it still the same key aspects of the instructional design process used in other regulated industries. These include:

Understanding end users: Delve into the mindset and capabilities of end users, considering their specific needs, challenges and environments. This knowledge forms the foundation for effective instructional design.

Task analysis: Employ task analysis to break down each distinct task associated with the medical device, detailing all relevant steps and providing supporting images to ensure expected performance.

Iterative testing: Test instructional materials with end users throughout the design process, identifying and resolving issues to ensure the instructions support end users.

Instructions should be established from the output of multiple processes, considerations and requirements. And while it is important to consider matters of general safety and performance, legal and product requirements, the most important factor in developing effective instructions is integrating with the HFE process.

Aligning Instructional Design with Human Factors Engineering

The design and development of instructional materials for medical devices align inherently with HFE principles. HFE provides essential inputs for effective instructional design, such as user and use environment descriptions, task use-error analysis and use-related risk analysis.

Overall, instructions should be optimized so that end users are guided to properly use a medical device, without causing harm to themselves or someone else. Ineffective instructional design can have a negative impact on user interactions with a device. Below are real-world examples of how poorly designed instructions have impacted users:

• A surgical team performing open surgery is unable to troubleshoot a device because troubleshooting instructions could not be located in the IFU due to the inappropriate placement of troubleshooting information and no Table of Contents to aid navigation to the instructions.
• Lay users who are undergoing cancer treatment and experiencing nausea and fatigue as side effects of their treatment do not have the energy nor cognitive ability to follow poorly designed menus or screens in a mobile app guiding their care.
• Lay users who are elderly and become overwhelmed by too much information presented all at once in a poster-style IFU.
• Lay caregivers who are under the stress and time pressure of an audible alarm indicating a potentially life-threatening situation cannot understand and follow paragraphs of text instructions to resolve the alarm.
• A user cannot visualize printed instructions clearly due to fold lines going through text and images.
• A user cannot navigate dense blocks of information to find specific warnings or cautions.
• A lay user does not understand how to perform a task because the image does not provide enough context of the device orientation.

Using HF inputs combined with instructional design techniques increases the usability of the instructional materials, and helps designers avoid these types of adverse situations.

HF Inputs that Guide Instructional Content Development

The initial considerations for developing any instructional material focus on who the users are and where they will be using or interacting with the device and the instructions. The characteristics of end users and their use environments serve to inform both the physical presentation of the instructions, whether in print or digital, as well as how the instructional content is written.

Consider the differences between healthcare professionals and lay users, as well as differences within each group of users:

• Instructions may need to accommodate healthcare professionals (e.g., surgeons, nurses, medical technicians) who typically have higher levels of education and training compared to lay users. Despite their knowledge, these users may experience high stress levels during procedures, fatigue and time pressures when using instructional materials, depending on their specialty and device use. Their use environments could be a doctor’s office, operating room, ambulance, or laboratory.
• Alternatively, lay users, including patients and caregivers (e.g., friends, family members), can have certain medical conditions, comorbidities and varying levels of overall health literacy, which all impact their ability to read, understand and follow instructional materials. These users tend to operate devices in their home (bathroom, kitchen, living room) or work environments (car, public bathroom) and could also travel with their medical device by car or airplane.

As you can see from these brief descriptions, there is a wide spectrum of user capabilities, limitations, expectations, and behaviors. Those user characteristics combined with users’ respective environmental conditions, including noise level, lighting, size and space, should all be considered when designing optimal instructions to support users. Factors such as font size, contrast, distance from the material, screen display, color use and accessibility of electronic instructions are determined with the end user and environmental conditions in mind. To illustrate this, consider the following examples:

• If the instructions are being accessed in an operating room, evaluate who will access the instructions and if instructions should be resized for easier viewing from a distance.
• If a lay user may administer a drug treatment with a drug delivery device at work, in their car, or in a bathroom, assess how the instructions will fit within the environment in addition to how the device will be used in that environment.
• If a device is used under a bright overhead light or in bright sunlight, consider whether electronic display of instructions will allow the user to see them clearly.

Instructional content (e.g., information, step by step instructions, images, warnings, cautions, etc.) can be derived from task use-error analysis and use-related risk analysis (URRA), both of which are key inputs from HFE. Task use-error analysis enables the development of clear guidance on correct device usage and highlights potential errors that could require special attention in the instructions.

Task analysis involves perceptual, cognitive and manual action (PCA) analysis to provide relevant details from the user’s perspective, such as audible, tactile and visual cues. Including these additional details within the instructions can be critical to guiding desired task performance. For example, if instructions point out that users may hear or feel a response from a device, this level of detail will help users know what to expect and look for, which is immensely helpful if they are in an environment with higher ambient noise levels. Such instructions provide a more complete context around the desired task to be completed, resulting in higher self-efficacy while using the device.

The URRA should be reviewed to identify critical tasks that may cause harm and warrant the inclusion of warnings, cautions, and precautions in the instructional materials. Given the URRA is structured around tasks and use steps, it can help identify placement of safety information so that users see, or are presented, the information in time to avoid hazardous situations. It is important to note that instructional materials are a tertiary consideration in addressing use-related risks, according to the risk management standard ANSI/AAMI/ISO 14971:2019 Medical devices – Application of risk management to medical devices. Devices are expected to be designed for safety and guard against risks before instructional materials are considered as a risk mitigation measure, as instructions are the least effective method of overcoming poor device design.

Optimize Instructions for Users Through Iterative HF Testing

It is essential to include early iterative HF testing to optimize the usability of instructional interfaces. Waiting until the end of product development and late-stage HF testing to assess these interfaces may uncover unexpected issues. When this happens, additional HF formative evaluations or unplanned supplemental HF summative evaluations are often required and can sometimes cause significant delays, and financial consequences.

Early and iterative HF testing establishes the evidence required to show that the instructions, as part of the overall device user interface, have been optimized for safe and effective use. There are three goals when including instructional materials in the overall HF testing plan:

1. Ensure the steps of use, images and information in the instructional materials support the correct performance of tasks.
2. Ensure warnings, cautions and other information for safety designated as risk control measures in the URRA can be found and understood.
3. Ensure the physical attributes of the instructional materials support users and avoid usability issues (such as page folds, organization of information, design of images, screen design and navigation, layout of pages, etc.).

Once an early prototype exists, low-fidelity instructional interfaces should be included in HF formative testing. Testing low fidelity interfaces is efficient because the interface is not yet fully developed, so changes and updates are easier, quicker and less costly to implement. Testing alternate versions of instructional designs can also be an effective early testing approach to understand user performance and preferences to down-select options. As the HF testing progresses into late-stage testing, then more focus can be put into developing a mature version for downstream HF evaluations.

A common method of evaluating instructional interfaces is asking end users to follow instructions word for word (also called directed use) and observe their performance compared to expected task performance. This approach captures design issues including omissions, instructions or elements that contribute to use errors, and language that is confusing or unclear to users. Note, due to regulatory expectations, directed use of instructions is not an acceptable method to include in HF validation evaluations for FDA submissions.

By implementing an instructional design process aligned with the HF process, issues can be uncovered early, and the design optimized well before conducting the HF summative or validation evaluation.

Conclusion

The success of medical devices hinges on the proper interaction between end users and the device. Effective instructional materials play a pivotal role in ensuring user safety, efficacy and overall satisfaction. Instructional design aligns with HFE principles and optimizes medical device usability. By prioritizing early and iterative testing of the design from the onset of the process, teams will be able to create superior instructional materials that guide end users to operate their devices with ease and confidence, ultimately enhancing patient outcomes and promoting safe and effective medical device use.