Targeted real-time assessment of chronic pain (TRAC-Pain) in youth: protocol for digital biosignature development through a prospective observational cohort study (Preprint)

BACKGROUND Approximately one in five children and adolescents live with chronic pain, with musculoskeletal (MSK) pain being one of the most prevalent sub-types. Unfortunately, less than half of youth with chronic pain experience improvements with existing evidence-based treatments. Self-report measures—the current gold-standard for monitoring the pain experience— are limited in their use as a single point-of-care assessment and vulnerability to recall bias. The ubiquitous adoption of wearable technology presents a promising solution for improved monitoring of the pain experience via real-time tracking through a multi-systemic lens. OBJECTIVE The purpose of this study is 1) to develop a digital biosignature of the pain experience in youth with chronic MSK pain, and 2) assess feasibility, acceptability, and appropriateness of captured data for future applications. METHODS All aspects of this study were designed in partnership with people with lived experience and patient advocacy partners. This is a longitudinal observational cohort study, with all study activities taking place remotely over a 12-week period. Up to 500 youth (14-24 years old) with chronic MSK pain will be enrolled through a multipronged recruitment strategy to ensure a representative sample. Participants will wear an Apple Watch throughout the study for continuous monitoring of physiological, sleep, and physical activity metrics. In addition, participants will complete brief ‘Daily Check-In’ surveys that include gold-standard measures of the pain experience (e.g., pain interference, mood, fatigue) and the option to report a ‘pain flare’ (i.e., temporary but noticeable worsening of usual symptoms). Participants will also complete a modified online Trier Social Stress Test and 30 second sit-to-stand task to capture individual responses to standardized challenges. Traditional machine learning and deep representation learning methods will be used to develop a digital biosignature of the pain experience. Accuracy of the biosignature will be assessed through measures of model performance as compared to gold-standard self-reports. RESULTS This study was funded in September 2024, with data collection beginning March 2025. As of August 2025, 132 participants are enrolled, with data collection and analysis ongoing. CONCLUSIONS This is the first study to leverage wearable health technology for real-time monitoring of the pain experience in youth with chronic MSK pain. Resulting digital endpoints are expected to heighten the rigor of clinical trials and provide opportunities for individually-tailored interventions. The second phase of this study will investigate the implementation of ‘wellness-alerts’ triggered by abnormal smartwatch readings. Alerts would empower users toward preemptive self-management strategies, thereby enhancing self-efficacy in those living with chronic MSK pain. CLINICALTRIAL ClinicalTrials.gov NCT06867757 https://clinicaltrials.gov/study/NCT06867757