Findings
The goal of sDHT design is to create tools that are functional, intuitive, accessible, and enjoyable to use, moving beyond merely minimizing use-errors. Human-centered design (HCD) is the preferred term over user-centered design, emphasizing the impact on many user groups beyond just the end-users. "Users" encompass end-users (patients/participants), carepartners, clinicians, investigators, and administrators.

Recommendations
Developers of sDHTs should adhere to the following HCD principles:
Empathetic: Take time to deeply understand users' needs, behaviors, and emotions, capturing this in the use specification.
Holistic: Consider the entire end-to-end user journey, including hardware, software, accessories, packaging, instructions for use, and training.
Iterative: Employ an iterative approach to designing, prototyping, testing, and refining, using formative evaluations to identify use-errors and gather usability data, capturing this in the use-related risk analysis.
User-centric: Improve usability by capturing user feedback in real-world settings, gradually recruiting larger, more diverse samples that represent the intended use population.
Inclusive: Collaborate with individuals representing all user groups by hiring them as consultants or creating user advisory panels to influence design decisions (co-design).
Multidisciplinary: Ensure the development team includes colleagues from various disciplines to bring diverse perspectives and innovative solutions.

Regulatory Considerations
The document ties the HCD process to risk management and eventual validation by recommending that findings from formative evaluations (used to identify use-errors) be captured in a use-related risk analysis. The approach aligns with the principles of the overarching V3+ framework.

Findings
Usability is a multi-domain concept that requires a combination of methods for evaluation. Evaluations fall into two types: formative (for design modification of prototypes) and summative (for demonstrating usability of the final product to a representative user sample). The user experience metrics fall into several domains, including: Satisfaction, Usefulness, Ease of use, Learnability, Efficiency, Memorability, Understandability, Actionability, Readability, and Use-errors. Metrics related to Satisfaction and Usefulness are always subjectively reported by users.

Recommendations
Developers should select metrics based on the specific usability-related domain being evaluated.
Subjective Data (e.g., Satisfaction, Usefulness): Capture through qualitative surveys, quantitative surveys (scales), interviews, focus groups, and think-aloud evaluations .
Objective Data (e.g., Ease of use, Use-errors): Capture through direct or indirect observation (e.g., counting steps/attempts, timing task completion), or by using data generated by the sDHT (e.g., error reports, timestamps, page load times).
Time-based Metrics: Evaluate Learnability (ease of first use), Efficiency (ease with experience), and Memorability (ease after non-use) by measuring ease of use at different points in time .
Information Presentation: If the sDHT presents clinical data or written information (instructions, warnings), evaluate Understandability, Actionability, and Readability .
Use-errors: Objectively capture the number, type, and recoverability of use-errors (actions, or lack thereof, that may result in harm) via observation and sDHT data, noting that "use-error" is preferred to "user-error".

Regulatory Considerations
While this guide does not reference regulatory bodies like the FDA, it is part of the V3+ framework and recommends that researchers prioritize essential documents like the use specification and use-related risk analysis before designing a usability study. Summative evaluations demonstrating usability against a representative user sample under intended use conditions are the standard for demonstrating product fitness.

Findings
Usability gaps in sDHTs remain a barrier to adoption, with many technologies failing to prioritize ease of use, accessibility, and diverse user needs​
Human-centered design is critical for ensuring that digital health solutions are intuitive, functional, and scalable across different healthcare environments​
Standardized usability metrics for evaluating digital health technologies are lacking, leading to inconsistent reporting and validation of usability outcomes​
Use-related risk analysis is essential to identifying and mitigating risks associated with user errors, ensuring the safety and effectiveness of sDHTs​
The V3+ framework provides a structured approach to integrating usability validation into digital health technology development, aligning with global regulatory expectations​

Recommendations
Developers should incorporate human-centered design principles from the outset, ensuring that usability, accessibility, and user needs are central to sDHT development​
Usability validation should be standardized, with clear methodologies for measuring usability, including satisfaction, ease of use, efficiency, and error mitigation​
Regulatory and clinical stakeholders should collaborate on defining best practices for usability evaluation, ensuring that digital endpoints are both meaningful and scalable​
Risk analysis should be iterative, with developers continuously refining their technologies based on real-world user feedback and testing​
The usability validation component of V3+ should be widely adopted to ensure that digital clinical measures meet patient-centered, regulatory, and technical expectations​

Regulatory Considerations
Regulators are emphasizing the need for usability validation to ensure that digital endpoints are both clinically relevant and patient-friendly​
sDHTs must comply with human factors engineering guidelines, aligning with global regulatory frameworks such as ISO 9241-210 and FDA usability requirements​
Data security, privacy, and interoperability must be ensured, particularly as sDHTs become integrated into remote monitoring and decentralized clinical trials​
Real-world evidence (RWE) should support usability validation, helping to bridge the gap between regulatory approval and real-world adoption​
Regulatory bodies should work toward standardizing usability testing methodologies, ensuring consistency across clinical research, digital endpoints, and medical device evaluations​

Findings
For an sDHT to be considered fit-for-purpose, a researcher or healthcare provider must understand the alignment between the sDHT's intended use (What it does, who uses it, where/when/how) and their own context of use . Key information for this assessment comes from the developer's Use Specification (detailing hardware, software, accessories, training) and Use-Related Risk Analysis (detailing warnings, harms from use-errors, and risk avoidance) . Usability validation evidence should cover study objectives, protocols, participant characteristics, metrics, and collection methods.

Recommendations
Researchers/providers should use the checklist to:
The Basics: Compare the sDHT's intended use to their context of use; if there is substantial overlap, existing evidence may be sufficient.
Use Specification/Risk Analysis: Gather detailed descriptions of the sDHT's hardware, software, accessories, written materials, training, cautions, warnings, and potential harms from use-errors to update their own Use Specification and Use-Related Risk Analysis .
Existing Evidence: Access existing usability validation study results (objectives, methods, participant characteristics, metrics, etc.) to determine its applicability and generalizability to their context of use .
Collaboration: Consider establishing a collaborative relationship with the developer to provide feedback for next-generation sDHTs, ensure version control, and potentially collaborate on future usability validation studies .

Regulatory Considerations
The document notes that if the sDHT is a regulated medical device, the intended use statement should already capture the answers to the basic questions. The entire checklist is framed around the V3+ framework, which is designed to ensure the rigor necessary for a product to be considered fit-for-purpose by all stakeholders.

Findings
Only a small number of novel digital measures have matured into regulatory qualification or efficacy endpoints.
Demonstrating that digital measures are meaningful to patients is a key challenge.
There is resistance from sponsors due to uncertainty about the value of DHT-derived endpoints in regulatory discussions.
Patient experiences are highly heterogeneous, making it difficult to generalize meaningful aspects of health.
Challenges exist in defining clinical significance and classifying digital measures as COAs vs biomarkers.

Recommendations
Engage patients and caregivers in facilitated discussions to incorporate their voices.
Determine the best method for gathering patient input on a case-by-case basis.
Engage patients to inform evidence needs, implementation, and value delivery.
Return summarized health data to participants to motivate and encourage communication with clinicians.

Regulatory Considerations
Understand the FDA's recent guidance on patient engagement in drug development.
Recognize the shift in evidence rigor required by the FDA for demonstrating meaningfulness.
Provide evidence that DHTs are usable, acceptable, and clinically relevant.
Utilize early engagement channels like CPIM and pre-LOI programs offered by the FDA.

Findings
A Use-Related Risk Analysis (URRA) is essential for identifying potential use-errors (actions or lack of action that may result in harm) and their associated use-related hazards (source of potential harm) when using an sDHT. The analysis must focus on user interactions with the sDHT, including all user groups (end-users, clinicians, carepartners, researchers, and administrators). Critical tasks are defined as those use-errors that may result in serious harm.

Recommendations
Developers should follow these five steps for the Use-Related Risk Analysis:
Describe all user tasks: Identify the sequence of actions a user performs to achieve a goal, which can be derived from sources like a task analysis or formative evaluations.
Describe potential use-errors: Identify and document potential actions or lack of actions that may result in harm for each task, noting that "use-error" is preferable to "user-error".
Describe potential use-related hazards: Determine the source of potential harm resulting from each identified use-error.
Develop a plan to minimize or eliminate known risks: The preferred approach is inherent safety by design (eliminating the error). If not feasible, use protective measures (e.g., warnings) or, as a last resort, provide instructions to users. Identify methods to evaluate the effectiveness of the chosen mitigation strategy.
Keep it up to date: The URRA is a living document requiring ongoing updates throughout the sDHT development and usability validation process.

Regulatory Considerations
The URRA is presented as a fundamental step within the V3+ framework for ensuring device usability and minimizing risk, implicitly setting the groundwork for regulatory compliance related to device safety. The minimization of use-errors, particularly for critical tasks, is a central tenet of device development best practices.

Findings
Decentralized Clinical Trials (DCTs), which shift activities away from sites, rely heavily on technology to reduce participant burden and improve access to trials. Digital platforms are essential for this shift, providing centralized data capture, remote monitoring, and streamlined workflows. Benefits include allowing participants to be monitored remotely, which can improve self-management and clinical outcomes, and giving researchers better insight into the real-world variability of disease activity. Currently, commercial platforms are often limited in functionality and face major challenges due to a lack of interoperability and specific data standardization protocols for clinical trial platforms, making it difficult to integrate third-party modules.

Recommendations
The paper strongly recommends the adoption of unified, integrated, and DCT-specific digital platforms to fully realize the benefits of decentralization. Platform developers should adopt international standards for health data exchange, such as HL7 FHIR and CDISC standards (PRM, CDASH, ADaM), to address the lack of data standardization and improve interoperability and modularity. Platforms should incorporate features that enhance participant engagement and adherence, such as customization options, simple user interfaces (UIs), push notifications, gamification, and allowing access to participant data . Security and governance teams are paramount to manage risks associated with malware, lost devices, and ensuring compliance with local legislation and data security protocols.

Regulatory Considerations
Digital platform design must maintain digital security and compliance with local legislation and data standards. The paper notes that a fully integrated, unified digital platform in a best-case scenario would use pre-existing standards (like CDISC and HL7) to guarantee interoperability. Adopting these standards and recommendations for data sharing, privacy, and security, as recommended by organizations like the Healthcare Information and Management Systems Society, is critical for future digital components used in DCTs. Improved data integrity and accountability in platforms could be further explored using technologies like blockchain to create an immutable ledger.

Findings
Usability gaps in sDHTs remain a barrier to adoption, with many technologies failing to prioritize ease of use, accessibility, and diverse user needs​
Human-centered design is critical for ensuring that digital health solutions are intuitive, functional, and scalable across different healthcare environments​
Standardized usability metrics for evaluating digital health technologies are lacking, leading to inconsistent reporting and validation of usability outcomes​
Use-related risk analysis is essential to identifying and mitigating risks associated with user errors, ensuring the safety and effectiveness of sDHTs​
The V3+ framework provides a structured approach to integrating usability validation into digital health technology development, aligning with global regulatory expectations​

Recommendations
Developers should incorporate human-centered design principles from the outset, ensuring that usability, accessibility, and user needs are central to sDHT development​
Usability validation should be standardized, with clear methodologies for measuring usability, including satisfaction, ease of use, efficiency, and error mitigation​
Regulatory and clinical stakeholders should collaborate on defining best practices for usability evaluation, ensuring that digital endpoints are both meaningful and scalable​
Risk analysis should be iterative, with developers continuously refining their technologies based on real-world user feedback and testing​
The usability validation component of V3+ should be widely adopted to ensure that digital clinical measures meet patient-centered, regulatory, and technical expectations​

Regulatory Considerations
Regulators are emphasizing the need for usability validation to ensure that digital endpoints are both clinically relevant and patient-friendly​
sDHTs must comply with human factors engineering guidelines, aligning with global regulatory frameworks such as ISO 9241-210 and FDA usability requirements​
Data security, privacy, and interoperability must be ensured, particularly as sDHTs become integrated into remote monitoring and decentralized clinical trials​
Real-world evidence (RWE) should support usability validation, helping to bridge the gap between regulatory approval and real-world adoption​
Regulatory bodies should work toward standardizing usability testing methodologies, ensuring consistency across clinical research, digital endpoints, and medical device evaluations​

Findings
The MS digital health space is still largely uncharted.
Balancing the needs and desires of different users when creating a digital solution is challenging.
Insufficient adherence to remote digital health solutions presents a challenge to long-term engagement.
Creating a digital solution that is both meaningful to end users and aligned with regulatory standards involves challenges and compromises.

Recommendations
Employ an iterative development process to continually refine digital health solutions.
Collaborate closely with healthcare professionals and patients throughout the design process.
Use behavioral science strategies to enhance user engagement and adherence.
Ensure that digital solutions are scientifically robust and meet regulatory standards.
Implement a prescription-based model to improve adherence and integration into clinical practice.

Regulatory Considerations
Conduct technical verification and clinical validation for each assessment in digital health solutions.
Ensure data privacy and cybersecurity measures are robust and comply with local regulations.
Maintain ongoing post-marketing surveillance to monitor safety and effectiveness.
Adapt solutions to meet diverse regulatory requirements across different geographies.

Findings
Sponsors must weigh the study benefits of PTs against potential burdens such as usability challenges, frequent reminders, or the need for connectivity and device maintenance.
Factors such as geography, socioeconomics, cultural practices, and technical literacy must be addressed to ensure PT accessibility across diverse patient populations.
Sponsors need to protect patient privacy by adhering to data protection standards and ensuring informed consent materials clearly communicate how data will be used and stored.
Effective maintenance, training, and 24/7 support systems for patients and sites are critical to ensure smooth operation and minimize disruptions.
Providing value to participants, such as progress feedback or gamification elements, can improve the patient experience and adherence.

Recommendations
Design Patient-Centric Materials: Simplify patient-facing materials, tailoring them to low health and technical literacy levels, and ensure patient input is incorporated during the design phase.
Identify and address geographic, socioeconomic, and cultural barriers to technology adoption to ensure inclusivity.
Offer multi-format training for patients and caregivers, provide troubleshooting guides, and ensure 24/7 multilingual technical support.
Safeguard patient data and inform patients of all potential risks associated with PTs. Develop backup plans for device failures or power outages.
Assess how PTs affect daily living, including comfort, usability, and the time required for setup and routine use, to minimize intrusion.

Regulatory Considerations
Ensure adherence to GDPR, HIPAA, and other relevant data protection laws. Clearly communicate privacy and data use details in consent forms.
Validate PTs for safety and suitability in the target population and ensure compliance with regulatory standards for medical devices.
Ensure that consent forms clearly describe PT functionality, benefits, and limitations in accessible language.
Global Adaptability: Account for regional laws, infrastructure limitations, and language requirements to ensure PT compatibility and regulatory compliance across geographies.

Findings
Human Factors Engineering (HFE) and Usability Engineering (UE) are fundamental for medical device safety and effectiveness. The HFE/UE process focuses on the interactions between people and devices, considering three major components: device users, device use environments, and the device user interface. The most important goal of this process is to minimize use-related hazards and risks. The FDA's HFE requirements are derived from the Quality System Regulation (QSR), specifically relating to Design Input (needs of the user and patient) and Design Validation (conformance to defined user needs). If risk analysis shows that use errors could lead to serious harm, HFE is explicitly required and must be submitted in premarket submissions (PMA, 510(k)).

Recommendations
Manufacturers should follow HFE/UE processes throughout the device development to improve design and minimize potential use errors. This involves an iterative process that runs parallel to product development. Key steps include:
User Research: Understand the intended users (e.g., professionals, patients, lay caregivers) and their characteristics (e.g., physical, cognitive abilities, experience).
Risk Analysis: Focus on potential use errors and identify critical tasks where errors could result in serious harm.
Formative Evaluation: Conduct evaluations during development to generate ideas for test scenarios, identify dangers early, and gather input for user interface improvements.
Design for Safety: Apply the hierarchy of risk control, prioritizing inherently safe design and protective measures (alarms, warnings) over instructions and training.
Usability Validation Testing: Conduct final summative testing with representative users under simulated real-world use conditions to demonstrate the device can be used safely and effectively.

Regulatory Considerations
The FDA recommends that manufacturers submit human factors data in premarket submissions for devices where risk analysis indicates that use errors could result in serious harm. The FDA has provided guidance on the content that should be included in these submissions, such as descriptions of intended users, use environments, user interface, risk analysis of use-related hazards, and results of validation studies. Manufacturers should also continue to monitor user interactions through postmarket surveillance and adverse event reporting.

Findings
Home use devices face unique environmental challenges, including power interruptions, fluid exposure, and travel-related conditions.
Lay users often have limited training and varying physical, cognitive, and emotional capabilities, requiring user-friendly designs and clear instructions.
Effective risk management should include designing risks out of the device wherever possible, supplemented by protective measures and labeling as needed.
Verification, validation, and human factors testing are essential to confirm device performance and usability under realistic home-use scenarios.
Postmarket considerations, such as customer service and Medical Device Reporting (MDR), are vital for maintaining device safety and compliance.

Recommendations
Design devices for diverse environmental conditions, such as variable power supplies, fluid exposure, and extreme temperatures.
Include safeguards like lock-out mechanisms, robust alarm systems, and protective casings to mitigate risks.
Develop user-friendly labeling and instructions, employing narrative formats and visuals to address low literacy or technical proficiency.
Conduct human factors engineering and usability testing to identify and resolve potential design issues, ensuring safe device operation by lay users.
Plan for postmarket support, including accessible customer service and robust systems for adverse event reporting.

Regulatory Considerations
Premarket submissions should document efforts to address environmental and user-related risks, supported by verification, validation, and usability data.
Devices requiring electrical power must meet applicable ANSI/AAMI standards for safety, including those related to electromagnetic compatibility.
Manufacturers must comply with labeling requirements under 21 CFR Parts 801 and 809, ensuring clear communication of warnings, instructions, and limitations.
FDA emphasizes the use of recognized consensus standards, such as IEC 62304 for software lifecycle processes and ANSI/AAMI HE75 for human factors engineering.
Devices must incorporate mechanisms for handling emergencies, including power outages, and provide clear labeling on disposal, maintenance, and troubleshooting.