The FDA estimates that use error contributes to thousands of medical device adverse events annually. For home-use devices, that number climbs even higher, and the consequences follow patients home.
Yet despite decades of guidance, device companies keep making the same human factors engineering (HFE) mistakes. The patterns are so predictable that experienced FDA reviewers can spot them in the first few pages of a submission. These are not minor oversights. They are fundamental misunderstandings about what it means to design for real humans in uncontrolled environments.
Here are the seven most common mistakes that derail home-use medical device submissions, and how to avoid them.
The mistake: Assuming comprehensive instructions and training materials can compensate for poor device design.
Device teams often approach home use like clinical use with extra documentation. They create detailed instruction manuals, training videos, and quick-reference guides, then assume users will follow them perfectly. When usability testing reveals confusion, the solution is always "better instructions."
This misses a fundamental truth: home users do not read manuals. They skim quick-start guides, watch 30 seconds of a YouTube video, and then wing it. Unlike clinicians who receive formal training, home users learn through trial and error, often with their health on the line.
The fix: Design the device to be intuitive without instructions. Instructions should clarify, not compensate. If users cannot perform critical tasks without referring to documentation, the design needs work, not better words.
The mistake: Testing in controlled lab environments that bear no resemblance to actual homes.
Most usability testing happens in bright, quiet, distraction-free labs. Users sit at ergonomic tables with perfect lighting and no interruptions. This environment has zero similarity to a real home, where devices get used in dim bedrooms, noisy kitchens, and cramped bathrooms.
The home environment includes poor lighting, interruptions from family members, pets that knock things over, and storage in medicine cabinets where humidity warps labels. It means users with visual impairments trying to read tiny text, or arthritic hands struggling with small controls while standing in a bathroom.
The fix: Test in realistic environments or simulate home conditions in your lab. Use representative lighting, add realistic distractions, and include environmental stressors. If you cannot test in actual homes, bring home-like conditions to your lab.
The mistake: Recruiting participants who are too willing, too available, or too experienced with medical devices.
Many studies recruit from pools of professional research participants, people who participate in studies for income. These "professional patients" are often healthier, more articulate, and more comfortable with medical devices than actual patients. They have learned to be helpful research participants, which means they struggle through confusing interfaces without complaining.
Real patients are anxious about their condition, stressed about using medical devices correctly, and often dealing with cognitive load from pain, medication, or fear. They give up when confused rather than working through problems.
The fix: Recruit from patient advocacy groups, disease-specific organizations, and healthcare provider networks. Specifically screen out frequent research participants. Include participants who are genuinely naive to similar devices.
The mistake: Failing to identify all tasks where use error could cause harm, especially setup and maintenance tasks.
Teams often focus on primary therapeutic tasks (delivering medication, taking measurements) while overlooking setup, calibration, cleaning, and troubleshooting procedures. These "secondary" tasks often present the highest use error risk because they are performed infrequently, under time pressure, or when the device is not working normally.
Consider a home dialysis machine. The primary task is running dialysis, but the highest-risk tasks might be initial setup, changing filters, or responding to alarms. These happen less frequently but with higher stakes.
The fix: Map the complete user journey, including unboxing, setup, routine maintenance, troubleshooting, and disposal. Analyze use error potential for each task, not just the primary function. Often the critical tasks are not the obvious ones.
The mistake: Conducting use-related risk analysis (URRA) as a documentation exercise rather than a design tool.
Many teams treat URRA as regulatory homework: a table to fill out for the FDA rather than a systematic analysis that drives design decisions. They identify obvious use errors, assign generic severity ratings, and call it complete. The analysis stays theoretical rather than connecting to real user behavior patterns.
Effective URRA goes deep on the cognitive and physical factors that lead to use errors. It considers how users actually behave under stress, what shortcuts they will take, and how errors cascade into larger problems.
The fix: Conduct URRA iteratively throughout design, not just at the end. Use real user research data to inform error likelihood assessments. Consider how multiple small errors compound into critical failures. Make URRA findings actionable for design teams.
The mistake: Creating HFE documentation that checks regulatory boxes without demonstrating actual validation.
Teams often focus on having the right sections and following the format guidance while missing the underlying questions FDA reviewers need answered: Can real users actually use this device safely? How do you know? What evidence supports that conclusion?
The documentation becomes a compilation of required elements rather than a compelling argument for safe and effective use. Key information gets buried in appendices, and the main narrative does not clearly connect user research findings to design decisions.
The fix: Write HFE documentation as a story that answers the FDA's fundamental question: "How do you know users can safely use this device?" Lead with key findings, make the connection between user research and design clear, and front-load the evidence that matters most.
The mistake: Treating post-market surveillance for human factors issues as a future problem rather than planning it during development.
Teams focus intensively on pre-market validation but give minimal thought to how they will detect and respond to use errors in the real world. This becomes critical for home-use devices because real-world use conditions differ significantly from validation study conditions.
Without planned surveillance systems, companies miss early warning signs of use error patterns that could lead to recalls or safety communications.
The fix: Design post-market surveillance systems during development. Plan specific metrics for tracking use error, establish thresholds for investigation, and create feedback loops from customer service, training programs, and healthcare providers.
Home-use medical devices require fundamentally different human factors approaches than clinical devices. The regulatory bar is higher because the stakes are higher: patients using these devices do not have clinical safety nets.
These seven mistakes are preventable, but only if teams recognize that home use is not just clinical use with different users. It is an entirely different design challenge that requires different research methods, different risk analysis, and different validation approaches.
Getting human factors right for home-use devices is not just about regulatory approval. It is about ensuring the devices actually help patients rather than becoming another source of stress in their healthcare journey.
Need support with human factors research for your home-use device? Usability House specializes in medical device usability testing and participant recruitment designed specifically for the unique challenges of home-use validation.