Findings
Nocturnal scratch is a clinically relevant behavior that impacts sleep quality, skin integrity, and overall disease burden in conditions like AD.
Traditional clinical outcome assessments (COAs) often fail to adequately measure scratching behavior, making digital measurement an important complement.
Digital health technologies, including wearables and sensor-based monitoring, enable passive and objective measurement of scratch behavior without relying on patient recall.
Regulatory agencies emphasize the importance of validation, ensuring digital measures are fit-for-purpose and aligned with patient needs.
Privacy, security, and compliance considerations must be prioritized, particularly in decentralized clinical trials using real-world data collection methods.

Recommendations
Digital measurement of nocturnal scratch should be integrated as an endpoint in clinical trials to capture patient-relevant outcomes objectively.
Sensor-based tools must undergo validation processes, including analytical and clinical validation, to ensure accuracy and reliability in different populations.
Stakeholders should align terminology and measurement definitions to support consistency across studies and regulatory submissions.
Usability testing with patients is critical to ensuring that wearable devices are practical and minimally burdensome.
Clinical trials should incorporate data privacy protections and clear informed consent processes to safeguard patient information.

Regulatory Considerations
FDA encourages early engagement to discuss digital endpoints, particularly through the Critical Path Innovation Meeting (CPIM) process.
Digital tools used for clinical investigations should align with 21 CFR Part 11 compliance for electronic records and data integrity.
Sponsors should ensure that digital health technologies used in trials meet validation criteria, including fit-for-purpose assessment and clinical relevance.
Privacy regulations, including GDPR and HIPAA, must be considered when handling patient data collected via wearable sensors.
Post-market monitoring and long-term validation studies are recommended to ensure continued accuracy and reliability of nocturnal scratch measurements.

Open source: Core Digital Measures of Nocturnal Scratch