Findings
Fragmented and inconsistent measurement approaches currently hinder the generation of decision-grade evidence for pediatric rare diseases. Small and geographically dispersed patient populations make traditional site-based clinical assessments operationally difficult and burdensome for families. Digital health technologies can capture subtle functional changes and "functional fingerprints" in home settings that are often missed during infrequent clinic visits. Standardized core digital measures across conditions allow for the aggregation of data and the creation of a shared evidence base for rare disorders. Meaningful aspects of health identified by patients and caregivers include motor function, communication, sleep quality, and autonomic stability.

Recommendations
Sponsors should adopt the core set of digital clinical measures to reduce trial timelines, lower development costs, and decrease participant burden. Researchers should prioritize passive and objective data collection to minimize the need for manual tracking by caregivers. Clinical trial designs should transition toward decentralized or hybrid models to improve access for children and families regardless of their location. Stakeholders should use the project's conceptual model to identify and customize digital measures that align with the specific health priorities of their target population. Developers should focus on human-centered design to ensure digital tools are usable and sustainable for pediatric patients and their support networks.

Regulatory Considerations
The FDA and EMA provide specific pathways and interaction opportunities to accelerate the acceptance of digital endpoints in rare disease trials. Digital measures must be validated as "decision-grade" endpoints to meet the evidentiary requirements for regulatory submission and marketing approval. Alignment with industry standards for data elements and interoperability is necessary to ensure data integrity across multi-site studies. Early engagement with regulatory bodies through meetings and formal submissions is critical for confirming the suitability of new digital biomarkers. Compliance with data privacy and ethical standards is paramount when collecting continuous, real-world data from vulnerable pediatric populations.

Findings
Long and Unpredictable Timelines: The COA Qualification Program is lengthy and unpredictable, with an average qualification time of six years. Nearly half of all submissions experience review times that exceed the FDA's own published targets.
Low Qualification and Uptake: As of October 2024, only seven COAs (8.1% of those listed) have been qualified, and only three of those have been used to support the benefit-risk assessment of new medicines. No COAs submitted after the passage of the 21st Century Cures Act in 2016 have been qualified.
Limited Regulatory Impact: Qualified COAs are consistently designated for "exploratory use" and have never been accepted as a primary endpoint in a clinical trial. In contrast, some non-qualified COAs have been used as key endpoints and included in drug labels, questioning the utility of the formal qualification pathway.
Discrepancy Between FDA Centers: There is a notable difference in how COAs are qualified between the drug (CDER/CBER) and device (CDRH) centers. The Kansas City Cardiomyopathy Questionnaire (KCCQ) was qualified by CDRH for use as a primary or secondary endpoint, while for drugs, it was only qualified as an "exploratory" measure.

Recommendations
Increase Transparency of Timelines: The FDA should publish its actual, historical review timelines for COA qualification so that drug developers can better plan and integrate these tools into their development programs.
Clarify the Use of Qualified COAs: The FDA should clearly articulate how and when qualified COAs can be used as primary or secondary endpoints to support regulatory decision-making and provide a clear pathway for updating a COA's status from "exploratory" to a key endpoint.
Publish Best Practices: Both sponsors and the FDA should be encouraged to publish their experiences with the qualification program to share best practices and learnings with the broader drug development community.
Create a List of Accepted Endpoints: The FDA should create and maintain a public list of qualified COAs that can be used as surrogate endpoints to support drug approval decisions, thereby increasing their utility and adoption.

Regulatory Considerations
"Qualified as a Measure" Ambiguity: The FDA's practice of qualifying COAs as "measures" for "exploratory use" creates regulatory uncertainty for sponsors, as it implies that significant additional evidence is still needed before the tool can be relied upon for a key endpoint.
Qualification is Not Required: The analysis shows that COAs can be accepted for regulatory decision-making and included in drug labels without going through the formal qualification program, suggesting that qualification is not a prerequisite for use as a reliable endpoint.
Unclear Path to Endpoint Progression: The current DDT guidance does not specify the process for upgrading a COA's qualification status (e.g., from exploratory to a primary endpoint) after additional data has been generated, which hinders its evolution and broader use.

Findings
The guidance applies to four types of Clinical Outcome Assessments (COAs): Patient-Reported Outcomes (PROs), Observer-Reported Outcomes (ObsROs), Clinician-Reported Outcomes (ClinROs), and Performance Outcomes (PerfOs). A COA is considered fit-for-purpose when the validation evidence is sufficient to support its context of use (COU). To determine if a COA is fit-for-purpose, sponsors must clearly describe the Concept of Interest (COI) and the COU, and present sufficient evidence to support a clear rationale for the COA's proposed interpretation and use. The rationale for using a COA should include up to eight components, such as justification for the COA type, capturing the important parts of the COI, appropriate administration and scoring, minimal influence from irrelevant factors or measurement error, and correspondence with the Meaningful Aspect of Health (MAH). The most direct assessment of how a patient feels or functions (MAH) should be used as the COI whenever possible.

Recommendations
Sponsors should use the Roadmap to Patient-Focused Outcome Measurement to guide the selection, modification, or development of a COA. The process begins with understanding the disease/condition (including patient perspectives) and conceptualizing clinical benefits and risks (defining the MAH, COI, and COU). When feasible, existing COAs are generally preferred, especially for well-established COIs, as this approach is often the least burdensome. If an existing COA is modified or used in a different context, additional evidence (e.g., cognitive interviews, psychometric studies) must be collected to justify its fitness for the new context of use. For new COA development, sponsors should involve patients, document all steps, and generally avoid using the new COA for the first time in a registration (pivotal) trial; a standalone observational study or early phase trial is recommended for evaluation.

Regulatory Considerations
Sponsors are encouraged to interact early and throughout medical product development with the relevant FDA review division to ensure COAs are appropriate for the intended COU. Sponsors should communicate their proposed COA-based endpoint approach, including the MAH, COI, COA type/name/score, and the final COA-based endpoint, ideally using the suggested format. The type and amount of evidence required to support the rationale for a COA's use is weighed against the degree of uncertainty regarding that part of the rationale. For ClinROs, it is recommended to use an assessor masked to treatment assignment and study visit for primary endpoints, if feasible. FDA strongly discourages proxy-reported measures for concepts known only to the patient (e.g., pain) and recommends using an ObsRO to measure observable behaviors instead when the patient cannot self-report.

Recommendations
Clearly define the concept of interest and its context of use to ensure COAs align with trial objectives.
Use conceptual and measurement frameworks to communicate how COAs measure patient experiences and generate interpretable scores.
Leverage existing COAs where possible, modifying them only when justified, and document all modifications rigorously.
Ensure COAs are accessible and inclusive, incorporating features like large fonts, touch interfaces, or audio assistance for diverse populations.
Conduct early engagement with FDA to discuss COA selection, development, and validation plans.

Regulatory Considerations
Fit-for-purpose validation requires evidence of conceptual alignment, scoring reliability, and sensitivity to clinically meaningful changes.
Digital health technologies used for COAs must comply with FDA’s guidance on data integrity, usability, and technical performance.
COAs intended for regulatory submissions must be developed and validated before pivotal trials to avoid jeopardizing trial outcomes.
Modifications to COAs or scoring methods during trials necessitate justification and revalidation.
Sponsors should submit comprehensive documentation on COA development, including scoring algorithms and item tracking matrices.

Findings
Regulatory Acceptance is Complex: Gaining regulatory acceptance for endpoints derived from Digital Health Technologies (DHTs) is a lengthy, multifaceted, and costly process that requires a global strategy and early health authority consultation.
"Fit-for-Purpose" is Key: A DHT's clearance or approval as a medical device does not automatically ensure it is fit-for-purpose in a clinical trial; its intended use must align with the specific context of use (COU) in the study.
Meaningfulness is a Hurdle: Demonstrating the clinical meaningfulness of novel digital endpoints, especially for abstract concepts like cognitive decline in Alzheimer's Disease, remains a significant challenge for regulatory acceptance.
International Harmonization is Lacking: Differences in regulatory requirements for DHT validation between major health authorities can delay or prevent the successful implementation of digital measures in global clinical trials.
Technology Changes Pose Risks: Software and hardware updates to DHTs during a clinical trial can have significant implications, potentially invalidating study results if not managed through a predetermined change-control plan.

Recommendations
Engage Health Authorities Early and Often: Sponsors should conduct multiple consultations with major health authorities (e.g., FDA, EMA) early in the development process to align on the Concept of Interest (COI), COU, and the validation roadmap.
Develop a Comprehensive Regulatory Strategy: A global regulatory strategy should be an integral part of the overall development plan, tailored to the program's objectives and endpoint hierarchy.
Establish "Fit-for-Purpose" Criteria: Before selecting a DHT, sponsors should establish the minimum technical and performance specifications required for the specific COU to guide the selection of a fit-for-purpose device.
Create a Conceptual Framework: For novel endpoints, sponsors should develop a conceptual framework that visualizes how the DHT-derived measure relates to meaningful health concepts and patient experiences.
Plan for Change and Missing Data: Sponsors should establish predetermined change-control plans with manufacturers to manage DHT updates and create risk management plans to minimize and handle missing data from remote acquisition.

Regulatory Considerations
Distinct Pathways in US vs. EU: The US FDA uses a risk-based approach for DHTs that are medical devices, while in Europe, CE marking for the intended COU is generally expected by the EMA.
Qualification is an Option, Not a Requirement: Both the FDA and EMA offer voluntary qualification programs for Drug Development Tools (DDTs), which can validate a DHT for a specific COU across multiple drug programs, though the process is resource-intensive.
Scientific Advice for Individual Programs: For DHTs used within a single drug development program, engaging with health authorities through scientific advice meetings is a more targeted and confidential pathway for gaining feedback and agreement.
Data Privacy and Security are Paramount: Sponsors must ensure that the collection, transfer, and storage of personal data via DHTs comply with all applicable regulations, such as GDPR in the EU, including cybersecurity and data transfer measures.

Findings
A comprehensive catalogue of over 340 symptoms and impacts was identified across ten symptom domains and two functional impact domains. Strongest evidence for relevance in early disease was found for tremor, fine motor dexterity, gait, stiffness, and slowed movements. Common non-motor symptoms include cognitive alterations, mood changes such as anxiety or depression, sleep disturbances, fatigue, and urinary dysfunction. Significant variability exists in how these concepts are currently measured and classified in literature, often confounding symptoms with functional impacts. There is a notable lack of diversity in existing research, with over 93% of qualitative data originating from white populations in the US, UK, and Canada.

Recommendations
Researchers and clinicians should utilize the proposed Domain-Category-Concept-Experience schema to ensure consistency and parsimoniousness in outcome selection. Selection of concepts for clinical trials should be evidence-based, focusing on those demonstrated to be both prevalent and bothersome to patients. Future research must prioritize the inclusion of culturally, racially, and geographically diverse populations to ensure the model's universal applicability. Stakeholders should adopt lay-friendly terminology, such as using ""slow movements"" instead of ""bradykinesia,"" to better reflect the patient perspective. Continuous re-evaluation of the model is necessary to maintain alignment with emerging biological staging systems for neuronal synuclein disease.

Regulatory Considerations
The consensus model was developed to align specifically with FDA guidance on patient-focused drug development (PFDD) to support regulatory-ready endpoints. Meaningful aspects of health should be identified through direct patient report to satisfy evidentiary requirements for ""fit-for-purpose"" clinical outcome assessments. Evidence-based SOFT report cards provide a transparent method for justifying the selection of concepts of interest in regulatory submissions. Early engagement with agencies is encouraged to ensure selected endpoints are sensitive to treatment effects and reflect what matters most to patients. Harmonization of concept definitions is a critical prerequisite for the successful qualification of new drug development tools.

Findings
The field lacks a centralized, standardized database of validated digital health technologies, making it difficult for researchers and clinicians to select appropriate tools.
Non-wearable sensors and software applications are the most common types of DHTs, with 83% of ambient technologies categorized as software or applications.
Most DHTs focus on mild cognitive impairment (MCI) and early Alzheimer’s disease, with fewer technologies validated for moderate or severe dementia stages.
Uneven Distribution of Dementia Subtypes – The review identified a gap in DHT validation for frontotemporal dementia (FTD) and Lewy Body dementia, with Alzheimer’s disease being the predominant focus.

Recommendations
Expand and maintain an open-access database of validated DHTs to improve accessibility and standardization.
Increase research on digital measures applicable to moderate and severe stages of dementia, as well as non-Alzheimer’s dementias.
Promote integration of wearable, ambient, and cognitive assessment tools to generate comprehensive digital phenotypes of patients.
Follow clear guidelines for analytical and clinical validation of DHTs to improve regulatory acceptance and research applicability.
Conduct more usability and feasibility assessments, especially for populations with cognitive decline, to ensure DHTs are accessible and effective in real-world settings.

Findings
There is a lack of standardized methodologies for deriving meaningful change thresholds for digital endpoints (DEs).
Challenges exist in identifying DEs that capture the most meaningful concepts to patients.
There is a need for further unification and synergy of efforts in the field, especially given the absence of clear cross-agency regulatory frameworks.

Recommendations
Form multidisciplinary task forces to develop consensus expert guidance recommendations.
Improve transparency and sharing of learnings within the industry.
Engage with regulatory bodies early and frequently throughout the DHT development process.
Use anchor-based methods as the primary approach for deriving meaningful change thresholds.
Ensure DEs reflect concepts that are meaningful to patients.

Regulatory Considerations
Early and frequent engagement with regulators is crucial.
DEs must reflect meaningful patient concepts and be validated early in the development process.
Anchor-based methods are preferred by regulatory authorities for deriving meaningful change thresholds.

Findings
COA-based endpoints should reflect meaningful patient health aspects and support clear treatment effect inferences.
Selection of endpoints requires a well-supported rationale, including evidence of their importance to patients.
Use of MSD and MSR approaches enhances the interpretation of treatment effects by linking COA scores to meaningful patient experiences. Proper anchors (e.g., global impression of severity) are essential for validating these approaches.
Frequency and timing of COA data collection must align with disease characteristics and study objectives.
Adjustments for potential practice effects and assistive device use are critical for robust outcome measurement.
Proper handling of missing data and sensitivity analyses ensure valid conclusions from COA-based endpoints.
Continuous, ordinal, and dichotomized endpoints require tailored statistical methods for analysis.
Early engagement with the FDA is crucial for aligning study designs and COA approaches with regulatory expectations.

Recommendations
Engage patients and caregivers early to identify meaningful endpoints and assess potential barriers to COA use.
Use anchor-based methods to validate COA scores and define meaningful thresholds for interpretation.
Develop and pilot test study protocols to ensure COA reliability, usability, and alignment with regulatory requirements.
Implement strategies to reduce participant burden, such as concise COA instruments and patient-friendly data collection methods.
Submit comprehensive documentation, including endpoint justification and scoring rationale, to FDA for feedback before trial initiation.

Regulatory Considerations
Endpoints must be supported by evidence of their fit-for-purpose status and alignment with the trial’s objectives.
COAs used in digital or adaptive formats must meet FDA’s standards for usability and data integrity.
Trials with nonrandomized designs require robust measures to mitigate bias in COA-based endpoint analysis.
Thresholds for MSD or MSR must be prespecified and justified with empirical evidence.
Sponsors must follow FDA guidance for submitting COA-based data, ensuring compliance with electronic data standards.

Findings
Limited evidence of clinical validity from pilot trials due to cost, time, and regulatory complexities.
Lack of standards for data integration across different tools and platforms.
Potential biases introduced by pre-existing algorithms.
Opaque data processing methods in BioMeTs.

Recommendations
Develop data, hardware, and software standards for BioMeTs.
Improve regulations for data rights, access, privacy, and governance.
Provide guidance on analytical methodologies for BioMeT data validation.

Regulatory Considerations
Early regulatory interactions with agencies like the FDA and EMA.
Ensuring data quality, integrity, reliability, and robustness.
Understanding regulatory pathways for BioMeTs in clinical trials.

Findings
Despite progress, DHTs are not yet fully accepted in clinical research.
Challenges include small study samples, unrepresentative samples, lack of normative data sets, feature selection bias, and replication issues due to sensor variability.
There is a need for a framework to identify and mitigate sources of variability in DHTs.

Recommendations
Develop a conceptual framework to identify and mitigate sources of variability.
Consider both active and passive monitoring approaches in study designs.
Align knowledge and data sharing across consortia to improve DHTs.
Emphasize normative data sets to establish ground truths for variability.
Encourage precompetitive collaborations to advance regulatory maturity.

Regulatory Considerations
Collaborative efforts like the 3DT project are essential for regulatory maturity.
Global regulatory agencies encourage data-driven engagement through consortia.

Findings
Meaningful outcome measures should align with patient priorities and clinical relevance, emphasizing aspects of health that impact daily life.
Digital tools must demonstrate value over traditional methods in capturing outcomes, especially in remote or decentralized contexts.
Questions about therapeutic benefit and endpoint sensitivity must address how these measures reflect patient improvements or disease progression.
Stakeholder collaboration is critical to selecting and validating concepts of interest and corresponding outcome measures.
Challenges include ensuring data privacy, operational feasibility, and addressing potential gaps in endpoint validation.

Recommendations
Engage patients and caregivers to identify meaningful aspects of health and concepts of interest relevant to their daily lives and goals.
Collaborate with clinicians to determine the clinical validity and utility of proposed measures and tools for endpoint development.
Ensure that DHTs selected for measurement add value beyond traditional methods and are feasible for clinical and real-world use.
Incorporate payer perspectives to align outcome measures with cost-benefit evaluations and reimbursement criteria.
Use the question bank as a flexible guide, adapting it to the specific needs and context of individual clinical trials.

Regulatory Considerations
Ensure endpoints and their measures meet regulatory standards for clinical relevance and sensitivity to therapeutic changes.
Align outcome measures with accepted core sets (e.g., COMET database) and validate them through stakeholder engagement.
Address concerns related to data privacy, scalability, and operational feasibility in the use of DHTs for endpoint development.
Plan for regulatory engagement to demonstrate the robustness of digitally-derived endpoints in pivotal clinical trials.
Provide evidence to support the incorporation of novel endpoints into regulatory and payer frameworks for decision-making.

Findings
Digitally-derived endpoints must align with trial goals, reflect the concept of interest (COI), and demonstrate clinical relevance.
Validation involves both verification of the digital tool's performance and ensuring the endpoint measures what it claims to measure.
Early-phase trials should assess usability, tolerability, and data privacy to ensure tools are operationally feasible for the intended population.
Regulatory alignment on endpoints, including their ability to demonstrate meaningful change, is critical before pivotal trials.
Statistical analysis plans must account for the unique aspects of digital endpoints, such as data quality and missing data considerations.

Recommendations
Define target populations and meaningful aspects of health (MAH) early in development to guide endpoint selection.
Conduct gap assessments of existing endpoints and propose clinically meaningful differences for patient outcomes.
Validate digital tools through verification (e.g., accuracy, reliability) and usability studies specific to the intended population.
Engage with regulators to align endpoints with evidentiary requirements for pivotal trials and label claims.
Prepare statistical plans and supporting evidence to justify the inclusion of digitally-derived endpoints in pivotal trials.

Regulatory Considerations
Verification and validation of DHTs should meet FDA and EMA standards, ensuring endpoints are fit-for-purpose and clinically relevant.
Align endpoints with regulatory requirements, demonstrating meaningful change that reflects treatment benefit.
Compile evidence of clinical validation, including how endpoints detect meaningful changes during treatment.
Address privacy, scalability, and operational feasibility to meet regulatory expectations for pivotal trials.
Consult regulatory guidance documents, such as FDA’s draft guidance on DHTs for remote data acquisition and EMA's methodologies for drug development.