Atopic eczema (synonymous with atopic dermatitis) is a chronic relapsing skin condition characterised by intense itching, dry skin, redness, inflammation and exudation. It affects mainly the flexor surfaces of the elbows and knees, as well as the face and neck.
The term 'atopic' refers to the association with atopy (a state of hypersensitivity to common environmental allergens that may be inherited), and differentiates atopic eczema from other forms of eczema such as irritant, allergic contact, discoid, venous, seborrhoeic and photosensitive eczema, which have different disease patterns and aetiologies.
Estimates of prevalence vary but suggest that the condition may affect as many as 15% to 20% of school-age children and 2% to 10% of adults. Most people with atopic eczema (more than 80%) experience mild disease; only around 2% to 4% of people with eczema have a severe form of the disease. Despite the lower prevalence, the presentation of disease in adults is often more severe and chronic in nature.
In most people with atopic eczema, the condition begins in early childhood, often in the first year of life, when it can be particularly severe. Findings from the National Child Development Study (NCDS), developed from the birth cohort of 1958, suggested an incidence of around 50 cases per 1,000 in the first year of life, falling to 5 new cases per 1,000 per year for the rest of childhood. In around 60% of children, the condition clears by the time they reach their teens. However, the tendency towards dry and irritable skin generally persists and later recurrences are common.
The aetiology of atopic eczema is complex and not fully understood. Genetic factors are important but environmental factors, such as house dust mites, pollen, tobacco, air pollution and low humidity, may cause its onset and/or exacerbate existing symptoms. More persistent disease has been consistently linked with early disease onset, severe widespread disease in early life, concomitant asthma or hay fever, and a family history of atopic eczema. The condition is exacerbated by soap and detergents, clothes containing wool or certain synthetic fibres, and extremes of temperature.
The severity of atopic eczema varies enormously, from an occasional dry, scaly patch to a debilitating disease, where much of the body is covered by excoriated, bleeding and infected lesions. Its course may be continuous for prolonged periods or of a relapsing-remitting nature, characterised by acute flare-ups.
Itching skin (pruritus) is a major symptom of atopic eczema. A vicious circle can occur, where itching and scratching damage the skin and increase inflammation, which in turn increases the itch. Damage to the skin from scratching can cause bleeding, secondary infection and thickening of the skin (lichenification).
The impact of atopic eczema on quality of life can be considerable, and varies according to disease severity. In addition to the burden imposed by daily treatment, studies have shown not only that the condition affects everyday activities such as work or school and social relationships, but also that people with atopic eczema may also experience anxiety, depression and other psychological problems. Sleep disturbance is common, especially during flare-ups, which in turn can lead to problems with irritability and lack of concentration. Severe atopic eczema in children can also have a significant impact on family life, with parents/carers having to cope with the demands associated with caring for a child with a chronic illness.
Historically, there have been variations over the clinical definition and diagnosis of atopic eczema. A UK Working Party has developed criteria for use in epidemiological studies, and these are now commonly used, although further validation is required. To qualify as a case of atopic eczema using these criteria, the person must have had an itchy skin condition in the past 12 months, plus three or more of the following:
a history of flexural involvement (that is, affecting the bends of the elbows or behind the knees)
a history of a generally dry skin
a personal history of other atopic disease (in children younger than 4 years, a history of atopic disease in a first-degree relative may be included)
visible flexural dermatitis as defined by a photographic protocol
onset before the age of 2 years (not used in children younger than 4 years).
There is uncertainty and a lack of standardisation around clinical assessment of disease severity, both in practice and in trial settings. Although a number of scoring systems have been used to categorise the disease as mild, moderate or severe, usually by aggregating scores from a range of symptoms and disease characteristics, none of these scoring systems has been accepted as a 'gold standard' and there remains general debate over their use.
Atopic eczema in childhood shows a reverse social class gradient, with higher rates in socioeconomically advantaged groups and smaller families. There is also evidence of variation in prevalence by region, with the highest rates recorded in the South East and industrialised Midlands, and the lowest rates in Wales and Scotland.
Management of atopic eczema takes place predominantly in primary care, and aims to relieve symptoms and prevent complications such as infections until remission occurs. This management involves skin care, anti-inflammatory treatment, and the identification and avoidance of exacerbating factors. Providing people with good-quality information about these issues is essential to successfully managing and treating atopic eczema. Referral to secondary care is advised only if the condition is severe and has not responded to appropriate therapy.
Emollients are a first-line therapy for atopic eczema and aim to retain the skin's barrier function (keeping water in and irritants or pathogens out) and to prevent painful cracking. Frequent and continuous use is recommended even in the absence of symptoms. Preparations available include bath oils, soap substitutes and moisturisers; generally the greasier the preparation, the better the effect, although people using very greasy products may consider them unacceptable.
Topical corticosteroids are the first-line treatment for flare-ups of atopic eczema. In order to reduce exposure to topical corticosteroids, they are used only intermittently to control exacerbations. Treatment regimens for topical steroids vary with disease severity, with clinicians usually recommending use of the mildest potency products possible to treat the condition, in order to minimise the potential adverse effects. Emollients are used together with the topical corticosteroids.
Where there are associated bacterial or fungal infections, corticosteroids are combined with other substances (such as antimicrobials or salicylic acid) in topical preparations.
Other treatments for atopic eczema include antihistamines, topical immunomodulators (see section 8), and wet wraps (when a layer of emollients with or without corticosteroids is applied to the skin and wrapped in wet bandages, followed by dry bandages, and left overnight), which may be used in an attempt to maximise the effect of treatment.
Treatments of last resort in resistant severe cases include systemic corticosteroids, phototherapy and systemic use of immunosuppressants.