We searched MEDLINE, the GREAT database, and the Centre of Evidence-based Dermatology web resource of systematic reviews, using the terms “atopic eczema”, “atopic dermatitis”, and “eczema”, in combination with search terms for diagnostic criteria, epidemiology, aetiology, immunology, quality of life, and treatment. Our search focused on articles published in English from January, 2015, to April, 2020. We also included key relevant papers outside this period, such as papers in the reference
SeminarAtopic dermatitis
Introduction
Atopic dermatitis, also known as eczema and atopic eczema, is one of the most common inflammatory disorders, affecting up to 20% of children and 10% of adults in high-income countries.1, 2 Globally, the prevalence of atopic dermatitis is increasing, although estimates in high-income countries are stabilising. The disorder is characterised by intense itching and recurrent eczematous lesions and has a heterogeneous clinical presentation.3 Although atopic dermatitis can occur at any age, the usual age of onset is in early childhood, typically at age 3–6 months. Evidence suggests that atopic dermatitis in adults is common, including both persistent and new-onset forms.4, 5
The causes of atopic dermatitis are complex and multifactorial. There is a strong genetic component, with evidence for multiple mechanisms of genetic risk. Loss-of-function mutations in the gene encoding filaggrin (FLG) are the most strongly and consistently reported genetic variants, supporting a key role for the skin barrier, as filaggrin is a major structural protein in the epidermis.6 Although genetics are clearly important in atopic dermatitis, the increasing global prevalence of the disorder highlights the role of environmental factors. Individuals with atopic dermatitis are at increased risk of having asthma, allergic rhinitis, and food allergy, and could be at increased risk of a wide range of health and psychosocial outcomes.3
In this Seminar, we aim to discuss major developments in the understanding of atopic dermatitis causes and long-term outcomes and to summarise the rapid expansion of therapeutic options, including targeted therapies.
Section snippets
Clinical signs
Atopic dermatitis is difficult to define because of its great heterogeneity in terms of clinical features, severity, and course. Without definitive tests, clinical signs are needed for diagnosis; a clinician's assessment is considered the gold standard.7 To aid diagnosis, several sets of criteria have been developed. While the UK Working Party criteria9, 10 are widely used for epidemiological studies of children, the Hanifin and Rajka criteria8 and an empirically derived, simplified version,
Epidemiology
Atopic dermatitis affects up to 20% of children and 10% of adults in high-income countries, based on annual self-reported prevalence estimates.3, 8, 23 In 2010, 230 million people worldwide were estimated to have eczema, with reports that the condition was the non-fatal skin disorder with the highest disease burden.24 Data on disease severity are scant but, in a multinational survey, 10–20% of adult patients with atopic dermatitis reported severe disease.25 In a population-based study from the
Natural history
Although the incidence of atopic dermatitis peaks during infancy, there has been a shift from thinking of atopic dermatitis as a resolving early childhood disease to an understanding that atopic dermatitis can have heterogeneous trajectories.38, 39 Patterns described in published work are varied and there is no consensus on optimal identification of subgroups. Trajectories can range from early transient disease to relapsing–remitting atopic dermatitis, chronic persistent atopic dermatitis, or
Pathophysiology and mechanisms of disease
The pathophysiology of atopic dermatitis involves a complex interplay between a dysfunctional epidermal barrier, skin microbiome abnormalities, and a predominantly type-2-skewed immune dysregulation (figure 2A, B).48, 49 These mechanistic drivers can promote and interact with others. For example, skin barrier weakness attributable to a filaggrin deficiency promotes inflammation and T-cell infiltration; colonisation or infection with Staphylococcus aureus damages the skin barrier and induces
Basic management strategies
Atopic dermatitis management aims to improve symptoms and establish long-term disease control. Management plans should be patient-centred and should include avoidance of individual trigger factors, skin barrier restoration using moisturiser, and a step-up and step-down approach aimed at reducing inflammation according to severity of the disease.128, 129, 130, 131, 132 The choice of anti-inflammatory therapy is largely based on disease severity; mild atopic dermatitis can usually be controlled
Health and psychosocial outcomes
Associations between atopic dermatitis and other so-called atopic diseases are well established, including increased risk of asthma, allergic rhinitis, and food allergies, particularly in those with severe and early-onset atopic dermatitis (appendix p 7).24, 183, 184, 185, 186, 187, 188, 189, 190, 191, 192, 193, 194, 195, 196, 197, 198, 199, 200, 201, 202, 203, 204, 205, 206, 207, 208 Traditionally, the term atopic march was used to describe the evolution from atopic dermatitis to asthma and
Quality of life and costs
The effect of atopic dermatitis on the quality of life of patients, their families, and caregivers is profound and multifaceted (appendix p 7).223 In the 2013 Global Burden of Disease Study, atopic dermatitis was identified as the skin disease with the greatest population-level disability among skin diseases.24 Similarly, the 2013 US National Health and Wellness Survey in adults reported that, among skin diseases, atopic dermatitis has the greatest detriment on skin-disease-specific
Concluding remarks
Atopic dermatitis is one of the most common chronic diseases with a high global burden in health-care costs and morbidity. Although many areas of uncertainty persist (panel 2), discoveries from genetics, molecular biology, epidemiology, and clinical medicine have spurred new disease concepts, including the notion of endotypes, and a broader understanding of health and psychosocial outcomes in atopic dermatitis. In most patients, atopic dermatitis constitutes a lifelong disposition with variable
Search strategy and selection criteria
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