Introduction

When testing a new medical device, ensuring it is not only effective but also usable and safe in the hands of real-world users is paramount. Human factors (HF) engineering – sometimes called usability engineering – focuses on how people interact with devices, aiming to minimise use errors and enhance user experience. Bridging human factors into clinical trials means proactively evaluating how usability impacts safety outcomes.

Why is this important?

Studies indicate that up to 50% of medical device failures stem from design issues leading to user error, and over a third of device recalls are due to usability-related design problems. In other words, a device might perform well in theory or lab tests, but if it’s confusing or difficult to use in practice, patient safety can be compromised. By integrating human factors considerations into clinical trials, sponsors can catch and address these issues early – effectively bridging the gap between usability and safety.

The Role of Human Factors in Device Trials

Traditionally, human factors validation studies are conducted separately from clinical efficacy trials. Regulatory guidance (FDA and EU) often calls for a dedicated usability test to confirm that the device’s user interface is safe and intuitive. However, clinical trials themselves offer an invaluable opportunity to gather human factors data under real-use conditions. HF engineering in a trial context is about observing and measuring how clinicians or patients actually use the device as part of the study and how those interactions affect outcomes.

The goal is twofold:

1) to ensure that any use-related risks are identified and mitigated during the trial, and

2) to verify that the device’s benefits observed in the trial aren’t undermined by user difficulties.

Human factors specialists often work with trial designers to incorporate usability endpoints or observations. For example, a trial might include assessments of user satisfaction, ease-of-use ratings, or documentation of any use errors that occur.

In fact, a recent review of clinical studies found that many device trials successfully included usability outcomes such as user satisfaction and ease of use, typically collected via questionnaires, interviews, or direct observation. Even a simple post-use survey for clinicians and patients can surface whether the device was user-friendly or if there were points of confusion. Capturing this data helps determine if any observed issues (like an adverse event) might be traceable to user error rather than a device flaw or patient factor.

Bridging Usability & Safety: Practical Strategies

To effectively bridge usability and safety in a trial, sponsors should integrate human factors thinking from the start:

• User-Centric Training: Ensure that all users (investigators, clinicians, and patient participants if they self-administer) are adequately trained on the device per its instructions for use. Training-related deficiencies can themselves be a human factor issue. A well-trained user base in the trial means that if problems occur, they’re more likely due to design issues rather than lack of user knowledge.

• Usability Data Collection: Plan to collect qualitative and quantitative usability data during the trial. This could involve adding a few questions about device usability in case report forms or patient diaries (e.g., “Rate the ease of using the device” or “Did you encounter any difficulty with the controls?”). For more critical devices, consider scheduling observational sessions where an expert watches how the device is used in practice by clinicians, or follow-up interviews to get detailed feedback. The investment can be scaled: even a quick questionnaire yields valuable insight, while in-depth observations provide richer context if resources allow.

• Monitor Use Errors as Safety Events: In the trial’s safety monitoring plan, include procedures to capture and analyse use errors – situations where the device was used incorrectly or not as intended, regardless of whether harm occurred. If a participant presses the wrong button or a clinician must redo a procedure due to device difficulty, record it. Investigate whether these incidents point to design shortcomings. Importantly, if a use error leads to an adverse event, the trial team should assess it from a human factors perspective: was the labelling clear, was the interface confusing? This analysis can feed into risk mitigation (either through design changes or updated training) before widespread marketing.

• Human Factors Endpoint (if applicable): For some innovative devices, the “usability” itself could be a key outcome. For instance, a novel at-home device might set a success criterion that 95% of users can correctly use it without assistance. In such cases, the trial’s results directly hinge on human factors performance, underscoring that usability is part of the device’s value proposition.

At its core, human factors engineering aims to ensure that the device-user interface promotes safe, effective, and error-free use. By implementing the above strategies, a clinical trial becomes a venue not just for testing whether the device works, but also how it works in the hands of intended users. This approach bridges the domains of usability and clinical performance.

Turning Human Factors Insights into Safer Devices

Incorporating human factors into trials has benefits that extend beyond the study. If the trial uncovers usability problems – say, users consistently struggle with a particular step – sponsors can address this proactively (perhaps by refining the device design or improving the instructions) before regulatory submission or commercialisation.

Regulators see this favourably; it demonstrates a commitment to minimising use-related risks. Indeed, FDA guidance emphasises using human factors testing to identify and mitigate use risks in realistic scenarios. Bridging usability and safety during trials also means that by the time a device reaches the market, both its clinical efficacy and its user-friendliness have been validated.

Finally, leveraging human factors in trials is a collaborative effort. Sponsors might engage human factors professionals to assist with study design and data analysis or work closely with site personnel to get observational insights.

A CRO with experience in device trials can also support this integration – for instance, Bioexcel routinely ensures that trial protocols for devices include considerations for user training and feedback, recognising that a device’s success depends on real-world user interaction.

In conclusion,

Bridging usability and safety in clinical trials is about seeing the full picture of device performance. A device that is effective in ideal conditions but prone to user error in practice could fail to deliver its promised benefits. By treating human factors as an integral part of the clinical investigation – through user-centric trial design, active monitoring of use-related issues, and iterative improvements – sponsors can confidently bring to market medical devices that are not only clinically effective but also safe and intuitive to use.