Human factors engineering (HFE), also called usability engineering, plays a critical role in the development of drug-device combination products. By focusing on how people interact with medical technologies, HFE ensures devices are safe, effective, and user-friendly. In recent years, the US Food and Drug Administration (FDA) has placed increasing emphasis on human factors data in product reviews. However, the pathway to meeting these expectations is not always straightforward. Developers face areas of ambiguity, particularly around validation studies, user interface requirements, and how to leverage existing data.
Challenges in Regulatory Expectations
The FDA has issued multiple guidance documents outlining its expectations for HFE in medical devices and combination products. While these guidances are valuable resources, their interpretation is not always consistent. Developers often encounter unexpected requests or scope changes that can delay product timelines. For example, while FDA commits under the Prescription Drug User Fee Act (PDUFA) to reviewing 90% of human factors validation protocols within 60 days, recent performance reports show that only a fraction are completed within that timeframe. These delays can significantly impact product development and approval timelines.
Validation of User Interface Specifications
A growing area of FDA focus is the validation of user interface specifications. Sponsors are now being asked to demonstrate that intended users—whether patients, caregivers, or healthcare professionals—can perform key physical tasks, such as removing syringe caps or activating autoinjectors. Often, the agency expects evidence that 95% of users are capable of these tasks. This request has generated confusion across the industry, particularly around whether such tests fall under human factors validation or general design controls. Most developers treat these as design input requirements, gathering early data from surrogate devices or literature studies to justify specifications.
Leveraging Existing Human Factors Data
Another major area of ambiguity is whether companies can reuse or “leverage” existing human factors data from similar or legacy devices. Many manufacturers have built robust risk analyses and validation data across multiple products that use the same delivery technology. They argue that repeating usability studies for every new product may be unnecessary, as potential use errors are already well understood. The FDA has published draft guidance on comparing new devices to validated reference products, but differences in interpretation remain. To avoid regulatory setbacks, early dialogue with the FDA is strongly recommended before scaling back validation efforts.
Strategies for Sponsors
Despite these challenges, sponsors can adopt several strategies to reduce ambiguity and streamline product development:
- Submit human factors validation protocols early, but only once device design, packaging, and labeling are stable.
- Use formative studies to identify and mitigate risks before conducting final validation studies.
- Benchmark FDA expectations by reviewing feedback and approval memos for similar products.
- Prepare thorough validation study reports that document risk analyses, test outcomes, mitigations, and justification for residual risks.
- Where possible, request FDA feedback on use-related risk analyses (URRAs) and comparative analyses through the appropriate regulatory submission process.
The Latest FDA Thinking
Recent FDA draft guidance on use-related risk analyses (URRAs) reinforces the agency’s emphasis on comprehensive documentation. Developers must outline all critical tasks, potential use errors, associated harms, and mitigations. Importantly, the FDA has clarified how sponsors can request waivers for validation studies in specific situations—such as when sufficient comparative data from similar products already exist. However, securing these waivers may require extensive justification and additional review time.
Conclusion
Human factors engineering is no longer a “nice-to-have” but a regulatory expectation for drug-device combination products. While ambiguities remain around validation requirements, user interface specifications, and the use of existing data, companies can reduce risk by planning early, engaging with FDA, and aligning development strategies with evolving guidance.
At EMMA International, we help life sciences companies navigate these complexities with tailored regulatory strategies, ensuring products not only meet FDA expectations but also achieve safe, effective, and timely market access.
For more information on how EMMA International can assist, visit www.emmainternational.com. Contact EMMA International at (248) 987-4497 or by email at info@emmainternational.com to learn more.
References
US Food and Drug Administration. Applying human factors and usability engineering to medical devices. 2016.
US Food and Drug Administration. Purpose and content of use-related risk analyses for drugs, biological products, and combination products. Draft guidance, 2024.
