Assessing nocturnal scratch with actigraphy in atopic dermatitis patients

Nocturnal scratch is one major factor leading to impaired quality of life in atopic dermatitis (AD) patients. Therefore, objectively quantifying nocturnal scratch events aids in assessing the disease state, treatment effect, and AD patients' quality of life. In this paper, we describe the use of actigraphy, highly predictive topological features, and a model-ensembling approach to develop an assessment of nocturnal scratch events by measuring scratch duration and intensity. Our assessment is tested in a clinical setting against the ground truth obtained from video recordings. The new approach addresses unmet challenges in existing studies, such as the lack of generalizability to real-world applications, the failure to capture finger scratches, and the limitations in the evaluation due to imbalanced data in the current literature. Furthermore, the performance evaluation shows agreement between derived digital endpoints and the video annotation ground truth, as well as patient-reported outcomes, which demonstrated the validity of the new assessment of nocturnal scratch.

Defining digital measurement of scratching during sleep, or “Nocturnal Scratch”: A review of the literature (Preprint)

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.

Use of technology for the objective evaluation of scratching behavior: A systematic review

Introduction

Pruritus is a common symptom across various dermatologic conditions, with a negative impact on quality of life. Devices to quantify itch objectively primarily use scratch as a proxy. This review compares and evaluates the performance of technologies aimed at objectively measuring scratch behavior.

Methods

Articles identified from literature searches performed in October 2020 were reviewed and those that did not report a primary statistical performance measure (eg, sensitivity, specificity) were excluded. The articles were independently reviewed by 2 authors.

Results

The literature search resulted in 6231 articles, of which 24 met eligibility criteria. Studies were categorized by technology, with actigraphy being the most studied (n = 21). Wrist actigraphy's performance is poorer in pruritic patients and inherently limited in finger-dominant scratch detection. It has moderate correlations with objective measures (Eczema and Area Severity Index/Investigator's Global Assessment: r_s(ρ) = 0.70-0.76), but correlations with subjective measures are poor (r² = 0.06, r_s(ρ) = 0.18-0.40 for itch measured using a visual analog scale). This may be due to varied subjective perception of itch or actigraphy's underestimation of scratch.

Conclusion

Actigraphy's large variability in performance and limited understanding of its specificity for scratch merits larger studies looking at validation of data analysis algorithms and device performance, particularly within target patient populations.

Development of digital measures for nighttime scratch and sleep using wrist-worn wearable devices

Patients with atopic dermatitis experience increased nocturnal pruritus which leads to scratching and sleep disturbances that significantly contribute to poor quality of life. Objective measurements of nighttime scratching and sleep quantity can help assess the efficacy of an intervention. Wearable sensors can provide novel, objective measures of nighttime scratching and sleep; however, many current approaches were not designed for passive, unsupervised monitoring during daily life. In this work, we present the development and analytical validation of a method that sequentially processes epochs of sample-level accelerometer data from a wrist-worn device to provide continuous digital measures of nighttime scratching and sleep quantity. This approach uses heuristic and machine learning algorithms in a hierarchical paradigm by first determining when the patient intends to sleep, then detecting sleep–wake states along with scratching episodes, and lastly deriving objective measures of both sleep and scratch. Leveraging reference data collected in a sleep laboratory (NCT ID: NCT03490877), results show that sensor-derived measures of total sleep opportunity (TSO; time when patient intends to sleep) and total sleep time (TST) correlate well with reference polysomnography data (TSO: r = 0.72, p < 0.001; TST: r = 0.76, p < 0.001; N = 32). Log transformed sensor derived measures of total scratching duration achieve strong agreement with reference annotated video recordings (r = 0.82, p < 0.001; N = 25). These results support the use of wearable sensors for objective, continuous measurement of nighttime scratching and sleep during daily life.

The Path Forward for Digital Measures: Suppressing the Desire to Compare Apples and Pineapples

Digital measures are becoming more prevalent in clinical development. Methods for robust evaluation are increasingly well defined, yet the primary barrier for digital measures to transition beyond exploratory usage often relies on a comparison to the existing standards. This article focuses on how researchers should approach the complex issue of comparing across assessment modalities. We discuss comparisons of subjective versus objective assessments, or performance-based versus behavioral measures, and we pay particular attention to the situation where the expected association may be poor or nonlinear. We propose that, rather than seeking to replace the standard, research should focus on a structured understanding of how the new measure augments established assessments, with the ultimate goal of developing a more complete understanding of what is meaningful to patients.

Development, Validation, and Interpretation of the PROMIS Itch Questionnaire: A Patient-Reported Outcome Measure for the Quality of Life Impact of Itch

Current patient-reported outcome measures for itch are limited and may not capture its full impact on health-related quality of life. We sought to develop, calibrate, and validate banks of questions assessing the health-related quality of life impact of itch as part of the Patient-Reported Outcomes Measurement Information System. A systematic process of literature review, content-expert review, qualitative research, testing in a sample of 600 adults, classical test theory methods, and item response theory analyses were applied. Exploratory and confirmatory factor analyses were followed by item response theory model and item fit analyses. Four itch-related item banks were developed: (i) general concerns, (ii) mood and sleep, (iii) clothing and physical activity, and (iv) scratching behavior. Item response theory and expert content review narrowed the item banks to 25, 18, 15, and 5 items, respectively. Validity of the item banks was supported by good convergent and discriminant validity with itch intensity, internal consistency, and no significant floor or ceiling effects. In conclusion, the Patient-Reported Outcomes Measurement Information System Itch Questionnaire banks have excellent measurement properties and efficiently and comprehensively assess the burden of itch.

Emerging Methods to Objectively Assess Pruritus in Atopic Dermatitis

INTRODUCTION

Atopic dermatitis (AD) is an inflammatory skin disease with a chronic, relapsing course. Clinical features of AD vary by age, duration, and severity but can include papules, vesicles, erythema, exudate, xerosis, scaling, and lichenification. However, the most defining and universal symptom of AD is pruritus. Pruritus or itch, defined as an unpleasant urge to scratch, is problematic for many reasons, particularly its negative impact on quality of life. Despite the profoundly negative impact of pruritus on patients with AD, clinicians and researchers lack standardized and validated methods to objectively measure pruritus. The purpose of this review is to discuss emerging methods to assess pruritus in AD by describing objective patient-centered tools developed or enhanced over the last decade that can be utilized by clinicians and researchers alike.

METHODS

This review is based on a literature search in Medline, Embase, and Web of Science databases. The search was performed in February 2019. The keywords were used "pruritus," "itch," "atopic dermatitis," "eczema," "measurements," "tools," "instruments," "accelerometer," "wrist actigraphy," "smartwatch," "transducer," "vibration," "brain mapping," "magnetic resonance imaging," and "positron emission tomography." Only articles written in English were included, and no restrictions were set on study type. To focus on emerging methods, prioritization was given to results from the last decade (2009-2019).

RESULTS

The search yielded 49 results in PubMed, 134 results in Embase, and 85 results in Web of Science. Each result was independently reviewed in a standardized manner by two of the authors (M.S., K.L.), and disagreements between reviewers were resolved by consensus. Relevant findings were categorized into the following sections: video surveillance, acoustic surveillance, wrist actigraphy, smart devices, vibration transducers, and neurological imaging. Examples are provided along with descriptions of how each technology works, instances of use in research or clinical practice, and as applicable, reports of validation studies and correlation with other methods.

CONCLUSION

The variety of new and improved methods to evaluate pruritus in AD is welcomed by clinicians, researchers, and patients alike. Future directions include next-generation smart devices as well as exploring new territories, such as identifying biomarkers that correlate to itch and machine-learning programs to identify itch processing in the brain. As these efforts continue, it will be essential to remain patient-centered by developing techniques that minimize discomfort, respect privacy, and provide accurate data that can be used to better manage itch in AD.

Digital Health Sensing for Personalized Dermatology

The rapid evolution of technology, sensors and personal digital devices offers an opportunity to acquire health related data seamlessly, unobtrusively and in real time. In this opinion piece, we discuss the relevance and opportunities for using digital sensing in dermatology, taking eczema as an exemplar.

Actigraphy-measured nocturnal wrist movements and assessment of sleep quality in patients with bullous pemphigoid: a pilot case-control study

BACKGROUND

Bullous pemphigoid (BP) is a distressing autoimmune bullous disease strongly associated with severe pruritus; however, data concerning pruritus in BP are still scarce. No clinical research evaluating the effect of BP on sleep quality has been conducted.

AIM

To evaluate the intensity of pruritus measured by nocturnal wrist movements (NWMs) and the sleep quality in patients with BP using actigraphy in comparison with nonpruritic healthy controls (HCs) with subsequent correlations with an itch visual analogue scale (VAS) as a subjective measure, disease severity [Bullous Pemphigoid Disease Area Index (BPDAI), urticaria/erythema, erosions/blisters] and serum total IgE level.

METHODS

In total, 31 patients with newly diagnosed BP (mean ± SD age 75.4 ± 12.3 years) and 40 nonpruritic HCs (age 73.5 ± 11.7 years) were recruited. All participants wore a sleep monitor (ActiSleep+) on the dominant wrist.

RESULTS

For patients with BP, median VAS score was 5.5 and median BPDAI was 43 (urticaria/erythema BPDAI was 16, erosions/blisters BPDAI was 29). Scratching, defined as bouts of NWMs, was significantly (P < 0.001) more intensive in patients with BP than in controls. Characteristic of BP was that scratching bouts corresponded with the slowest wrist movements. There were no correlations with VAS, BPDAI or total IgE level. Compared with HCs, patients with BP presented significant (P < 0.001) sleep disturbances, as determined by sleep efficiency, waking after sleep onset and average duration of awakening, and these were strongly correlated with urticaria/erythema BPDAI.

CONCLUSION

Nocturnal wrist movements measured by actigraphy are more intensive in patients with BP than in nonpruritic HCs, and characteristically slow movements. Actigraphy method showed very low sleep quality in patients with BP, thus severity of BP has a negative impact on sleep.

Detection of Nocturnal Scratching Movements in Patients with Atopic Dermatitis Using Accelerometers and Recurrent Neural Networks

Atopic dermatitis is a chronic inflammatory skin condition affecting both children and adults and is associated with pruritus. A method for objectively quantifying nocturnal scratching events could aid in the development of therapies for atopic dermatitis and other pruritic disorders. High-resolution wrist actigraphy (three-dimensional accelerometer sensors sampled at 20 Hz) is a noninvasive method to record movement. This paper presents an algorithm to detect nocturnal scratching events based on actigraphy data. The twofold process consists of segmenting the data into "no motion," "single handed motion," and "both handed motion" followed by discriminating motion segments into scratching and other motion using a bidirectional recurrent neural network classifier. The performance was compared against manually scored infrared video data collected from 24 subjects (6 healthy controls and 18 atopic dermatitis patients) demonstrating an score of 0.68 and a rank correlation of 0.945. The algorithm clearly outperformed a published reference method based on wrist actigraphy ( score of 0.09 and a rank correlation of 0.466). The results suggest that scratching movements can be discriminated from other nocturnal movements accurately.

Assessment of severity and burden of pruritus

Chronic pruritus is a complex multifactorial symptom associated with many different diseases that represents a diagnostic and therapeutic challenge for physicians. In order to better manage chronic pruritus, a detailed medical history, individualized diagnostic procedures and treatment approaches are necessary. Treatment should not only take itch into consideration, but also scratching-induced skin lesions and accompanying disorders such as anxiety, depression and insomnia. Various standardized questionnaires and scales have been developed to assist in the characterization and assessment of these parameters. Monodimensional scales (e.g. the visual analogue scale) represent a simple method for assessing pruritus intensity and are frequently used; however, they can easily be confounded and may indicate the level of satisfaction regarding the medical care provided rather than the itch course. The Dynamic Pruritus Score and Itch-Free Days questionnaire enable a closer assessment of patient responses to treatment. Because chronic pruritus has the potential to greatly impact the quality of life, it is important that physicians recognize it as a major issue. The Dermatology Quality of Life Index is an instrument that is used in a variety of dermatological conditions, but may be unsuitable for measuring pruritus of extracutaneous origin. The ItchyQol is a tool designed specifically for those suffering from pruritus. Additional tools, such as the Hospital Anxiety and Depression Scale, take psychiatric comorbidities into consideration. Recommendations from European (EADV-based Task Force Pruritus) and international (International Forum for the Study of Itch) expert groups focusing on assessment instruments for chronic pruritus are also provided in this article.

Assessment of pruritus in patients with psoriasis and atopic dermatitis: subjective and objective tools

Pruritus is a major symptom of skin disease. The quest to identify a valid and reliable method to assess this important symptom has led to the development of a myriad of measurement tools. Some clinical trials using subjective measurements of itch intensity have reported itch intensity levels in psoriasis that are close to severity levels found in atopic dermatitis. Although it is possible that we have previously underestimated the severity of pruritus in psoriasis, these unexpected findings prompted us to review and evaluate these subjective methodologies. We provide an overview of the current tools available to measure itch severity, including subjective rating scales and questionnaires and objective measures of scratch activity through videotape observation and wrist actigraphy. We discuss the advantages and limitations of these methods and encourage consideration of a novel objective method of evaluation.