Content » Vol 99, Issue 3

Clinical Report

Measurement of Nocturnal Scratching in Patients with Pruritus Using a Smartwatch: Initial Clinical Studies with the Itch Tracker App

Akihiko Ikoma, Toshiya Ebata, Laurent Chantalat, Kimitoshi Takemura, Fabienne Mizzi, Michel Poncet, Didier LeClercq
DOI: 10.2340/00015555-3105


Three clinical studies were conducted to test a newly-developed app for smartwatches, which included an algorithm to measure nocturnal scratching using acceleration data. The first study in 5 patients with atopic dermatitis demonstrated high reliability of the app for measurement of scratching compared with video monitoring (positive predictive value 90.2 ± 6.6%, sensitivity 84.6 ± 10.2%, correlation of scratching duration per h r = 0.851–0.901, p < 0.001). The second study in 20 patients with atopic dermatitis and 10 healthy volunteers showed that total scratching duration in patients was significantly longer than in healthy volunteers and correlated positively with Eczema Area and Severity Index (EASI) scores. In the third study, conducted in an open-entry manner in which 201 evaluable participants measured nocturnal scratching, those who self-reported itch or pruritic diseases had a significantly longer duration of scratching than those who did not. In conclusion, this app has a high reliability and potential clinical usefulness for measurement of nocturnal scratching.


This paper reports 3 clinical studies to measure scratching in patients with chronic itch, using a new app developed for use in widely-used smartwatches. The results indicate that the smartwatch app is reliable and useful for measurement of scratching during sleep, enabling the indirect, but objective, evaluation of itch severity. The app has potential for use in daily clinical settings.

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