Exploring the FDA EDDO Guidance from a Human Factors Perspective

The recent FDA guidance on Essential Drug Delivery Outputs (EDDOs) emphasizes the importance of identifying, verifying, and validating design outputs critical to drug delivery device performance. While the guidance explicitly states that studies to validate EDDOs are not traditional human factors (HF) studies, in my opinion and experience, the connection between EDDOs and human factors engineering is significant. This article examines how human factors professionals contribute to defining and validating EDDOs, ultimately enhancing drug delivery device safety and usability.

The Overlap Between EDDOs and Human Factors

The Human Element in EDDO Input Definitions

EDDOs are inherently tied to user interactions with the device. For instance, parameters such as activation force, cap removal force, or break-loose force must align with the physical capabilities of intended users. In my opinion, the human factors team is equipped to provide critical inputs in defining EDDOs due to their specialized expertise. They usually can provide input by:

• Leveraging Anthropometric Data: Using comprehensive scientific literature, such as the ANSI AAMI HE75 standard, to understand user physical capabilities and limitations.

• Conducting Foundational Evaluations: Designing and executing studies aimed at collecting empirical data on maximum human capabilities related to specific device interactions. This ensures the EDDO specifications align with realistic intended user capabilities and constraints.

Validating EDDO Outputs

According to the FDA guidance, the validation of EDDOs must ensure that devices conform to defined user needs and intended uses, including testing production units under actual or simulated use conditions. The appropriate validation method depends on the application type, development stage, and specific EDDOs. Remember, the EDDO guidance is not referring to traditional summative evaluations with the term validation, if you want to learn more about the traditional human factors validations check our post “Preparing a Successful Summative Evaluation”. The guidance outlines the following approaches to validate EDDOs:

• Clinical Studies: These may include reliance on safety/effectiveness data for reference listed drugs (RLDs) or pharmacokinetic/pharmacodynamic (PK/PD) studies to validate performance metrics like dose accuracy or flow rate.

• Simulated Bench Testing: Evaluations designed to determine if users can perform tasks within the EDDO specification, such as exerting required forces or identifying auditory cues.

• Anthropometric Data Assessments: These involve testing specific population groups to ensure usability across a range of physical capabilities, such as confirming that cap removal force is manageable for elderly users.

• Literature-Based Validation: Utilizing existing data to support certain parameters, such as injection depth requirements for target populations.

For instance, when developing a prefilled syringe (PFS), validation methods may include clinical studies for deliverable volume, simulated bench testing for glide force, and anthropometric assessments for cap removal force. These diverse approaches collectively ensure the device meets both regulatory and practical user requirements.

Practical Implications for Human Factors Teams

While traditionally the human factors specialists are focused on usability and validation activities, HF teams now face increased pressure to properly define EDDO inputs and validate them after development. This expansion of duties reflects the critical importance of HF teams in the medical device and pharmaceutical industries.

However, this added workload could create challenges for HF teams, who are already tasked with ensuring comprehensive usability validation. Balancing traditional responsibilities with the new demands for EDDO  may strain resources, potentially delaying timelines or increasing the risk of oversight. To mitigate these risks, organizations must recognize the strategic value of HF teams and provide adequate support, resources, and collaboration opportunities across departments, I recommend to check our post about differences between large and smaller size human factors teams to read more about consequences on limiting resources. This approach emphasized the indispensable role of HF specialists in ensuring both regulatory compliance and user-focused development.

As human factors specialists face new challenges with EDDOs, I suggest the following strategies to adapt in these expanded responsibilities:

• Leverage Established Literature: Begin with foundational resources like ANSI/AAMI HE75 or ISO/TR22411 to gain a comprehensive understanding of the types of information typically collected and the terminology used. Follow this by conducting a thorough literature review to identify the latest research, ensuring that your approach to defining EDDO inputs is informed by the most current data and methodologies.

• Expand Evaluation Techniques: Explore evaluation methods beyond traditional cognitive assessments. Many valuable approaches in human factors and ergonomics, such as physical and psychophysiological evaluation techniques, are underutilized in the medical device and pharmaceutical sectors. These methods can provide really valuable insights into design development and usability. For an introduction to these techniques, consider consulting the Handbook of Human Factors and Ergonomics Methods, which provides practical guidance on integrating diverse evaluation methods into your practice.

Conclusion

The FDA’s EDDO guidance provides a robust framework for ensuring drug delivery device performance. While these activities are not explicitly categorized as traditional HF studies, many aspects of EDDO identification, verification, and validation inherently depend on human factors expertise. This increasing reliance highlights the critical responsibility of HF professionals in ensuring that EDDOs are meticulously aligned with human capabilities and practical usability.  This expanded role for human factors practitioners, highlights their responsibility not only to apply traditional cognitive techniques but also to venture into underutilized methods in the medical device space such as physical and psychophysiological evaluations. By adopting a broader range of methodologies, HF professionals can conduct a more thorough analysis of user capacities and abilities, ensuring that devices are optimized for all user groups, particularly those with unique physical or cognitive challenges.