Peer-reviewed article
Smartwatch-Derived Nocturnal Scratching Metrics Capture Disease Activity and Severity in Pediatric Atopic Dermatitis.
Iwai F, Nishida T, Kanai R, Arima T, Takase T et al. ·
Summary
Written by AI, not yet AICS's view · claude-haiku-4-5-20251001This study tested whether smartwatches can measure scratching in children with atopic dermatitis (a skin condition causing itching) during the night. Fifty children aged around 9 years wore Apple Watches with a tracking app for up to 14 nights while receiving treatment. The researchers found that scratch metrics correlated with disease severity and improved as children got better, suggesting smartwatch data could help monitor the condition.
Key points
- All scratch metrics (count, duration, and burden) correlated with baseline disease severity (r = 0.60-0.64, p < 0.001)
- Scratch metrics correlated with serum TARC, a biomarker of disease activity (r = 0.58-0.60, p < 0.001)
- Reductions in scratching paralleled clinical improvement in the first phase of treatment (r = 0.67-0.71, p < 0.0001)
- Scratch burden index had the best ability to identify children who improved clinically (AUC = 0.78)
- Authors concluded that while these metrics show promise, prospective validation is needed before use in routine clinical monitoring
Limitations
The study is small (50 children) and observational with no control group, measuring only over 5-14 nights in the early treatment phase. The cross-sectional design of biomarker analyses and short monitoring period mean the findings cannot establish whether scratching metrics can predict future outcomes or guide long-term treatment decisions.
Abstract
Background/Objectives: The itch-scratch cycle is a key driver of exacerbation in atopic dermatitis (AD) and requires objective monitoring, yet patient-reported itch scores are often unreliable in children. This study aimed to evaluate smartwatch-derived nocturnal scratching metrics as digital biomarkers of disease activity and treatment response in pediatric AD. Methods: In this prospective observational study, 50 children (median age 9 years) with physician-diagnosed AD wore an Apple Watch with the Itch Tracker application for 5-14 nights during initiation of topical therapy. Three scratch metrics-scratch count rate (SCR), scratch duration ratio (SDR), and scratch burden index (SBI, duration × intensity)-were analyzed. Associations with clinical outcomes [Eczema Area and Severity Index (EASI), Patient-Oriented Eczema Measure (POEM)], serum thymus and activation-regulated chemokine (TARC), and itch numerical rating scale (NRS) were examined. Logistic regression models were evaluated to examine whether these metrics could identify children who achieved clinically meaningful improvement, defined as EASI-50 plus ≥ 4-point POEM reduction. Results: All scratch metrics correlated with baseline EASI (r = 0.60-0.64, p < 0.001) and serum TARC (r = 0.58-0.60, p < 0.001). Reductions in scratching paralleled clinical improvement (r = 0.67-0.71, p < 0.0001). Among models, the SBI-based logistic regression demonstrated the best discriminative performance (AUC = 0.78, 95% CI: 0.64-0.92). Conclusions: Wearable-derived nocturnal scratching metrics showed moderate but consistent associations with disease severity and short-term improvement. Although predictive capability remains to be established, these metrics may serve as treatment-responsive digital measures. Given the cross-sectional nature of biomarker analyses and other study limitations, further prospective validation is required before clinical application in real-world pediatric AD monitoring.
Findings the Hub has extracted
Each claim below is labelled by its type of design and links back to this report.
- Intervention
- Smartwatch-derived nocturnal scratching metrics using Apple Watch with Itch Tracker application
- Population
- 50 children (median age 9 years) with physician-diagnosed atopic dermatitis
Key finding
Scratch metrics correlated with baseline EASI severity (r = 0.60-0.64, p < 0.001) and serum TARC biomarker (r = 0.58-0.60, p < 0.001)
F et al. · Europe PMC · 28 Apr 2026