Scratch Scoring by a Sheet-shaped Body Vibrometer in Nocturnal Sleep: A Pilot Study Compared with Infrared Video Recording.

Itching tends to worsen at night in patients with itchy skin diseases, such as atopic dermatitis. Unconscious scratching during sleep can exacerbate symptoms, cause sleep disturbances, or reduce quality of life. Therefore, evaluating nocturnal scratching behaviour is important for better patient care. However, no report exists on the specific detection of overnight scratching behaviour of patients with atopic dermatitis using a non-wearable sensor. A novel algorithm was developed to specifically detect scratching behaviour using a non-wearable sheet-shaped body vibrometer placed under the mattress. To evaluate the algorithm, the sleep of 7 patients with atopic dermatitis and 3 healthy participants was simultaneously measured using an infrared camera and the sheet-shaped body vibrometer. Scratching time was then used as the gold standard, which was determined visually from the infrared video. The proposed method of detecting vibration was compared with the conventional method using the activity score measured by a sheet-shaped body vibrometer. Spearman's correlation coefficients of the conventional and proposed methods were 0.72 and 0.89, respectively. The Bland-Altman plot results confirmed that the proposed method avoided overestimation of scratching time in patients with short scratching times because it excluded activities other than scratching behaviour, such as turning over.