Identifying Phenotypes of Atopic Dermatitis in a Longitudinal United States Cohort Using Unbiased Statistical Clustering

Artificial Intelligence: A Snapshot of Its Application in Chronic Inflammatory and Autoimmune Skin Diseases

Immuno-correlated dermatological pathologies refer to skin disorders that are closely associated with immune system dysfunction or abnormal immune responses. Advancements in the field of artificial intelligence (AI) have shown promise in enhancing the diagnosis, management, and assessment of immuno-correlated dermatological pathologies. This intersection of dermatology and immunology plays a pivotal role in comprehending and addressing complex skin disorders with immune system involvement. The paper explores the knowledge known so far and the evolution and achievements of AI in diagnosis; discusses segmentation and the classification of medical images; and reviews existing challenges, in immunological-related skin diseases. From our review, the role of AI has emerged, especially in the analysis of images for both diagnostic and severity assessment purposes. Furthermore, the possibility of predicting patients' response to therapies is emerging, in order to create tailored therapies.

Atopic dermatitis phenotypes based on cluster analysis of the Danish Skin Cohort

BACKGROUND

Despite previous attempts to classify atopic dermatitis (AD) into subtypes (e.g. extrinsic vs. intrinsic), there is a need to better understand specific phenotypes in adulthood.

OBJECTIVES

To identify, using machine learning (ML), adult AD phenotypes.

METHODS

We used unsupervised cluster analysis to identify AD phenotypes by analysing different responses to predetermined variables (age of disease onset, severity, itch and skin pain intensity, flare frequency, anatomical location, presence and/or severity of current comorbidities) in adults with AD from the Danish Skin Cohort.

RESULTS

The unsupervised cluster analysis resulted in five clusters where AD severity most clearly differed. We classified them as 'mild', 'mild-to-moderate', 'moderate', 'severe' and 'very severe'. The severity of multiple predetermined patient-reported outcomes was positively associated with AD, including an increased number of flare-ups and increased flare-up duration and disease severity. However, an increased severity of rhinitis and mental health burden was also found for the mild-to-moderate phenotype.

CONCLUSIONS

ML confirmed the use of disease severity for the categorization of phenotypes, and our cluster analysis provided novel detailed information about how flare patterns and duration are associated with AD disease severity.

Disease modification in inflammatory skin disorders: opportunities and challenges

Progress in understanding of the mechanisms underlying chronic inflammatory skin disorders, such as atopic dermatitis and psoriasis vulgaris, has led to new treatment options with the primary goal of alleviating symptoms. In addition, this knowledge has the potential to inform on new strategies aimed at inducing deep and therapy-free remission, that is, disease modification, potentially impacting on associated comorbidities. However, to reach this goal, key areas require further exploration, including the definitions of disease modification and disease activity index, further understanding of disease mechanisms and systemic spillover effects, potential windows of opportunity, biomarkers for patient stratification and successful intervention, as well as appropriate study design. This Perspective article assesses the opportunities and challenges in the discovery and development of disease-modifying therapies for chronic inflammatory skin disorders.

Uncommon variants in FLG2 and TCHHL1 are associated with remission of atopic dermatitis in a large longitudinal US cohort

Atopic dermatitis (AD) is a relapsing inflammatory skin disease; filaggrin (FLG) variation has been consistently associated with its pathogenesis. Filaggrin-2 (FLG2) and trichohyalin-like-1 (TCHHL1) are members of the same protein family (S100 fused-type proteins), are similar in structure to FLG, and may be involved in AD pathogenesis. We sought to evaluate the association between variation in FLG2, TCHHL1 and AD remission. We sequenced FLG2 and TCHHL1 in a longitudinal AD cohort using targeted capture-based massively parallel sequencing. Association between individual alleles and AD remission was evaluated with generalized estimating equations for binary outcomes. Association between groups of alleles and AD remission was evaluated using a genetic algorithm to group alleles. We identified two loss-of-function (LoF) mutations in FLG2 (Ser2377Ter, Arg2207Ter) and 2 LoF mutations in TCHHL1 (Gln656Ter, Gln294Ter), none of which were associated with AD remission. Common (MAF > 5%) alleles in FLG2 were similarly unassociated with AD. No common alleles in TCHHL1 were associated with AD remission after multiple testing correction. Among self-described whites, a group of 34 uncommon alleles in FLG2 were associated with increased AD remission (OR 7.64e17; 95% CI 4.41e17-1.32e18; adjusted p < 1.0e-16). Twelve uncommon alleles in TCHHL1 trended toward association with increased AD remission (OR 23.46; 95% CI 7.07-77.89; adjusted p = 0.064). Among self-described African Americans, 13 uncommon FLG2 alleles were associated with increased AD remission (OR 21.01; 95% CI 11.90-37.09; adjusted p < 1.0e-16). No TCHHL1 uncommon allele groups were associated with AD remission among African Americans. Our study supports the role of uncommon alleles in FLG2 and TCHHL1 in AD pathogenesis.

The financial burden of out-of-pocket healthcare expenses on caregivers of children with atopic dermatitis in the United States

Background

Atopic dermatitis (AD) is associated with elevated financial costs, including out-of-pocket (OOP) expenses. Yet, the full burden of OOP expenses in children with AD is poorly understood.

Objectives

We sought to characterise categories, impact, and associations of caregiver-reported OOP AD healthcare expenses for US children.

Methods

An online survey was administered to National Eczema Association members (N = 113 502). Inclusion criteria (US resident; respondent age ≥18; self or caregiver report of AD diagnosis) was met by 77.3% (1118/1447) of those who completed the questionnaire.

Results

Caregivers of children (<18 years) with AD reported increased healthcare provider (HCP) visits, comorbid food allergy, cutaneous infections, and topical antimicrobial use (p < 0.005 for all), and increased OOP expenses for hospitalisation, emergency room visits, emollients, hygiene/bathing products, childcare, and specialised cleaning products, and clothing/bedding (p < 0.05 for all) compared to adults with AD. Children with AD had increased median total yearly OOP expenditures ($860 vs. $500, p = 0.002) and were more likely to spend ≥$1000 OOP per year (48.9% vs. 40.0%, p = 0.03). In children, yearly OOP expenses ≥$1000 were associated with increased AD severity, flares, HCP visits, prescription polypharmacy, and step-up therapy use (p < 0.005 for all) compared with adults. Predictors of harmful financial impact among children included black race (adjusted OR [95% confidence interval]: 3.86 [1.66-8.98] p = 0.002) and ≥$1000 annual OOP expenditures (6.98 [3.46-14.08], p < 0.0001).

Conclusion

Children with AD have unique and increased OOP expenses that are associated with significant disease burden. Strategies are needed to reduce OOP costs and improve clinical outcomes in children with AD.

Evaluating the Longitudinal Course of Atopic Dermatitis: Implications for Clinical Practice

Atopic dermatitis (AD) is characterized by a heterogenous longitudinal course with varying severity, flares, and persistence. However, AD course is not routinely assessed in clinical practice or controlled trials. Our objective was to review the longitudinal course of AD in children and adults and discuss implications for routine practice and clinical trials. We conducted a focused review of the published literature, including retrospective, prospective, and interventional studies, clinical trials, and consensus guidelines. Estimates of AD persistence varied widely across studies but suggested that AD can indeed persist through childhood and into adulthood. Predictors of persistence are broad and include both disease-intrinsic and disease-extrinsic (i.e., environmental) factors. In real-world practice, most individuals with AD experience fluctuations in the signs and symptoms over time and do not experience persistent clearance of skin lesions. Clinical trials use mainly static measurements that do not take into account fluctuations in course, which may confound treatment effects. The heterogenous temporal pattern of AD can be incorporated into routine practice to better set expectations and offer a realistic prognosis. AD course should be routinely incorporated into clinical decision making. Future studies are needed to develop a standardized approach to AD assessment and treatment that includes longitudinal course.

Time Trends in the Prevalence of Atopic Dermatitis in Korean Children According to Age

This study aimed to explore time trends in the prevalence of atopic dermatitis (AD) according to age in Korean children. We observed changes in the estimated annual prevalence of AD using data from the Korean National Health Insurance Service (NHIS) and Statistics Korea between 2003 and 2018. In each year, the highest prevalence was evident among children aged 12 to 23 months, and then the prevalence decreased with age. The annual prevalence of AD in Korean children under the age of 18 slightly increased from 4.0% in 2003 to 4.5% in 2018. During this period, the prevalence in children aged 6 to 18 years increased from 1.9% in 2003 to 3.1% in 2018, while that of infants aged less than 24 months substantially decreased. Among children who were born in 1991, 1997, 2000, 2003 and 2006, the slopes of decreasing trend lines over age 6 were similar. Comparing children born in 2009 and 2012 with those born before 2006, the more recent the birth year, the higher the prevalence of AD over age 6. In conclusion, time trends of the annual prevalence of AD in Korean children from 2003 through 2018 were different according to age group. These results suggest that AD development during infancy is decreasing whereas either a late-onset AD or early-onset, persistent phenotype is likely to increase. Different strategies according to age are required for more effective prevention and treatment of AD in Korean children.

Using a Machine Learning Approach to Identify Low-Frequency and Rare FLG Alleles Associated with Remission of Atopic Dermatitis

Atopic dermatitis (AD) is a common relapsing inflammatory skin disease. FLG is the gene most consistently associated with AD. Loss-of-function variants in FLG have been previously associated with AD. Low-frequency and rare alleles (minor allele frequency < 5%) in this gene have been given less attention than loss-of-function variants. We fine sequenced the FLG gene in a cohort of individuals with AD. We developed a machine learning‒based algorithm to associate low-frequency and rare alleles with the disease. We then applied this algorithm to the FLG data, searching for associations between groups of low-frequency and rare FLG alleles and AD remission. A group of 46 rare and low-frequency FLG alleles was associated with increased AD remission (P = 2.76e-11). Overall, 16 of these 46 FLG variants were identified in an independent cohort and were associated with decreased AD incidence (P = 0.0007). This study presents an application of statistical methods in AD genetics and suggests that low-frequency and rare alleles may play a larger role in AD pathogenesis than previously appreciated.

A systematic scoping review of racial, ethnic, and socioeconomic health disparities in pediatric dermatology

BACKGROUND/OBJECTIVES

Health disparities encompass a wide range of personal, societal, environmental, and system-based factors that contribute to inequitable health and health outcomes in vulnerable patient populations. The goal of this work was to scientifically summarize the existing published North American research on disparity as it pertains to pediatric dermatology.

METHODS

A systematic review was performed according to PRISMA guidelines. A medical librarian performed electronic searches from multiple electronic databases from their dates of inception to March 2021. Title and abstracts were reviewed by authors, identifying articles for full review. Data on article characteristics and identified disparities were then extracted and collected in a spreadsheet.

RESULTS

Fifty-one articles met final inclusion criteria, of which 25 highlighted disparities due to race/ethnicity, 13 highlighted disparities due to socioeconomic (SES), and 13 highlighted disparities due to both race/ethnicity and SES. The most frequent study designs were cross-sectional or survey, followed by retrospective cohort. Only two were prospective cohort studies. Disparities reported included reduced access to care and medications, increased school absenteeism, reduced knowledge about skin care including sun protection, increased hospitalizations and emergency department visits, and severe and persistent disease in the setting of minority race and poverty, among other indicators.

CONCLUSIONS

There are few, scattered research studies addressing disparity in pediatric dermatology. Greater focus will be needed in the future to improve knowledge of sources of disparity and its detrimental effects on the health of children, to rectify the notable disparity under-reporting of disparity research.

Immunological Aspects of Skin Aging in Atopic Dermatitis

The cutaneous immune response is important for the regulation of skin aging well as for the development of immune-mediated skin diseases. Aging of the human skin undergoes immunosenescence with immunological alterations and can be affected by environmental stressors and internal factors, thus leading to various epidermal barrier abnormalities. The dysfunctional epidermal barrier, immune dysregulation, and skin dysbiosis in the advanced age, together with the genetic factors, facilitate the late onset of atopic dermatitis (AD) in the elderly, whose cases have recently been on the rise. Controversial to the healthy aged skin, where overproduction of many cytokines is found, the levels of Th2/Th22 related cytokines inversely correlated with age in the skin of older AD patients. As opposed to an endogenously aged skin, the expression of the terminal differentiation markers significantly increases with age in AD. Despite the atenuated barrier disturbances in older AD patients, the aged skin carries an impairment associated with the aging process, which reflects the persistence of AD. The chronicity of AD in older patients might not directly affect skin aging but does not allow spontaneous remission. Thus, adult- and elderly subtypes of AD are considered as a lifelong disease.

Predicting persistence of atopic dermatitis in children using clinical attributes and serum proteins

BACKGROUND

Atopic dermatitis (AD) is the most common inflammatory skin disease in children, with 30% of all those diagnosed developing chronic or relapsing disease by adolescence. Such disease persistence cannot yet be predicted. The aim of the present study was to predict the natural course of AD using clinical parameters and serum proteins.

METHODS

Sera of 144 children with AD (age 0-3 years) were analyzed for IgE and 33 cytokines, chemokines, and growth factors. Patient disease course until the age of 7 years was assessed retrospectively. Unsupervised k-means clustering was performed to define disease endotypes. Identified factors associated with AD persistence at the age of 7 years were validated in children with AD in an independent cohort (LISA Munich; n = 168). Logistic regression and XGBoosting methods followed by cross-validation were applied to predict individual disease outcomes.

RESULTS

Three distinct endotypes were found in infancy, characterized by a unique inflammatory signature. Factors associated with disease persistence were disease score (SCORAD), involvement of the limbs, flexural lesion distribution at the age of 3 years, allergic comorbidities, and disease exacerbation by the trigger factors stress, pollen exposure, and change in weather. Persistence was predicted with a sensitivity of 81.8% and a specificity of 82.4%. Factors with a high impact on the prediction of persistence were SCORAD at the age of 3 years, trigger factors, and low VEGF serum levels.

CONCLUSION

Atopic dermatitis in infancy comprises three immunological endotypes. Disease persistence can be predicted using serum cytokines and clinical variables.