Background Digital sensing solutions represent a convenient, objective, relatively inexpensive method that could be leveraged for assessing symptoms of various health conditions. Recent progress in the capabilities of digital sensing products has targeted the measurement of scratching during sleep, traditionally referred to as nocturnal scratching, in patients with atopic dermatitis or other skin conditions. Many solutions measuring nocturnal scratch have been developed; however, a lack of efforts toward standardization of the measure’s definition and contextualization of scratching during sleep hampers the ability to compare different technologies for this purpose. Objective We aimed to address this gap and bring forth unified measurement definitions for nocturnal scratch. Methods We performed a narrative literature review of definitions of scratching in patients with skin inflammation and a targeted literature review of sleep in the context of the period during which such scratching occurred. Both searches were limited to English language studies in humans. The extracted data were synthesized into themes based on study characteristics: scratch as a behavior, other characterization of the scratching movement, and measurement parameters for both scratch and sleep. We then developed ontologies for the digital measurement of sleep scratching. Results In all, 29 studies defined inflammation-related scratching between 1996 and 2021. When cross-referenced with the results of search terms describing the sleep period, only 2 of these scratch-related papers also described sleep-related variables. From these search results, we developed an evidence-based and patient-centric definition of nocturnal scratch: an action of rhythmic and repetitive skin contact movement performed during a delimited time period of intended and actual sleep that is not restricted to any specific time of the day or night. Based on the measurement properties identified in the searches, we developed ontologies of relevant concepts that can be used as a starting point to develop standardized outcome measures of scratching during sleep in patients with inflammatory skin conditions. Conclusions This work is intended to serve as a foundation for the future development of unified and well-described digital health technologies measuring nocturnal scratching and should enable better communication and sharing of results between various stakeholders taking part in research in atopic dermatitis and other inflammatory skin conditions.

BACKGROUND Digital health technologies represent a convenient, objective, relatively inexpensive method that could be leveraged for assessing scratching during sleep (nocturnal scratch) in patients with inflammatory skin conditions. However, a lack of standardization of outcome measures for this symptom hampers the ability to compare different technologies for this purpose. OBJECTIVE To address this gap, we systematically reviewed the literature for definitions of 1) scratching in patients with skin inflammation, and 2) sleep in the period during which such scratching occurred. METHODS We performed two systematic literature reviews of English-language studies published between January 1996 and March 2022. The first search used the terms “scratch”, “itch” or “pruritus” in the titles of publications in the PubMed, IEEE, Scopus, and Web of Science databases, limiting the search to dermatitis-related studies in humans. We also searched the titles of publications in the PubMed and Google Scholar databases for the search terms “sleep opportunity” and “intended sleep”, to capture definitions of sleep in the context of when dermatitis-related scratching occurred. RESULTS In all, 29 studies contained a definition of scratch, itch, or pruritis related to inflammation, two of which also described sleep-related variables. Definitions for scratching differed widely according to the tool(s) used for assessment. From these studies, we developed an evidence-based and patient-centric definition of nocturnal scratch: An action of rhythmic and repetitive skin contact movement performed during a delimited time period of intended and actual sleep, that is not restricted to any specific time of the day or night. We also developed ontologies of relevant concepts and properties related to scratching and sleep. CONCLUSIONS Investigators can use these ontologies and properties to develop detailed, objective, standardized measurements for use by clinical researchers, clinicians, technology developers, regulators, patients, and payers. Inclusion of more advanced properties remains to be decided by specific research groups or tool developers. CLINICALTRIAL n/a