Key points

Introduction

Atopic dermatitis (AD) (also known as atopic eczema or eczema) is by definition a chronic condition. The original diagnostic criteria proposed by Hanifin and Rajka and the most recent guidelines issued by the American Academy of Dermatology both include a “chronic or relapsing” history as an essential feature. Little is written, however, about the clinical course of AD. This could be because many patients with AD present with symptoms early in life, and hence most research has focused on pediatric disease. Although there are relatively few publications about adult disease, recent population-based estimates of AD prevalence among US children and adults were similar. These data suggest either AD begins in childhood and persists through adulthood, childhood AD remits for some and begins in adulthood for others, or some combination thereof. A number of practical and methodological challenges to studying a chronic episodic condition have limited the description of the long-term course of AD. In the following sections, we review the available data and discuss the implications for clinical care and future research.

Introduction

Atopic dermatitis (AD) (also known as atopic eczema or eczema) is by definition a chronic condition. The original diagnostic criteria proposed by Hanifin and Rajka and the most recent guidelines issued by the American Academy of Dermatology both include a “chronic or relapsing” history as an essential feature. Little is written, however, about the clinical course of AD. This could be because many patients with AD present with symptoms early in life, and hence most research has focused on pediatric disease. Although there are relatively few publications about adult disease, recent population-based estimates of AD prevalence among US children and adults were similar. These data suggest either AD begins in childhood and persists through adulthood, childhood AD remits for some and begins in adulthood for others, or some combination thereof. A number of practical and methodological challenges to studying a chronic episodic condition have limited the description of the long-term course of AD. In the following sections, we review the available data and discuss the implications for clinical care and future research.

Why is the long-term course of atopic dermatitis important to study?

Data about the long-term course of AD are necessary for informing clinicians and patients about prognosis and guiding treatment decisions at an individual level and for planning at the health systems level. Traditionally, AD was considered a pediatric condition and families were told most children “outgrow” AD by adolescence. Such imprecise information is insufficient for patients who desire detailed prognostic data. Moreover, it is insufficient for understanding the impact of potentially disease-modifying interventions, a topic of particular salience in the current era of systemic drug development.

When does atopic dermatitis begin?

The symptoms of AD may begin at any age, although many sources suggest that most incident AD occurs in early childhood. Estimates may be affected by study designs that focus only on pediatric or clinic populations or by the diagnostic criteria used. For example, a recent review in the Lancet states “in roughly 60% of cases, the disease manifests during the first year of life,” citing a prospective study that follows patients until age 7 and a retrospective cohort of clinic patients. Studies including only children may underestimate the average age of disease onset because they would not capture adult-onset cases. Similarly, clinic-based samples are likely biased toward patients with more persistent or severe disease that begins earlier in life, and may not be not be representative of the general AD population. Additionally, some commonly used diagnostic criteria, including the Hanifin and Rajka criteria and the UK Working Party criteria, include onset in childhood as a minor criterion. Studies using these criteria may estimate lower rates of adult disease compared with studies that do not select patients based on age of onset. Data that are less likely to be susceptible to selection bias suggest that AD may commonly begin in adulthood. For example, a population-based survey in the United States found that 54% of those with AD reported disease onset after age 18. More data are needed to understand disease incidence over the life span and whether adult-onset disease is different from disease that begins in childhood.

Does atopic dermatitis permanently resolve, and if so, when?

Existing data are unable to answer this question. An older review found that 50% to 70% of individuals with AD improved over 10 years of follow-up, although the definition of clearance varied by study and ranged from 11% to 92%. Population-based birth cohort studies with multiple assessments of individuals over 2 decades found that rates of “short-term” or “apparent” clearance decreased when accounting for subsequent recurrences using estimates of annual period prevalence repeated every 3 to 7 years. More frequent measurement of disease activity every 6 months in a US cohort of children and young adults with AD who had prior treatment with a topical calcineurin inhibitor (and therefore may be more likely to have persistent disease) suggests that although some patients seem to improve with age, most continue to have active disease at multiple time points. Longitudinal studies that follow individuals throughout adulthood are needed to better understand the periodicity of disease activity and patterns over the life course.

Is atopic dermatitis a lifelong condition?

Genetic and physiologic data support the idea of AD as a lifelong condition. It is well established that AD runs in families, and in the past decade genetic discoveries have implicated multiple genes involved in the development and maintenance of the skin barrier and immune function. Patients with AD often have xerosis that predates their diagnosis. In fact, “a history of generally dry skin from birth” was found to be one of the most predictive characteristics and hence was included among the minimum set of discriminators in the UK Working Party diagnostic criteria. Although the evidence is mixed, some studies have shown that physiologic differences, such as transepidermal water loss (TEWL), may precede the clinical manifestations of AD and are detectable as early as day 2 after birth. Moreover, experimental evidence from 2 randomized trials suggest that maintenance of the skin barrier with emoillients during the neonatal period may delay or prevent the development of clinical signs of AD.

These data suggest that individuals with AD have an elevated probability of developing clinical symptoms throughout life, as illustrated in Fig. 1 . Even normal-appearing skin in patients with AD has evidence of differences in skin barrier function, dendritic cell population, and cytokine profiles, supporting the concept of subclinical disease. The factors influencing the transition to clinically evident disease (both disease onset and disease flares) are an area of active research: investigators have explored the modulation of immune priming by hygiene, environmental factors, psychosocial factors, and diet. Early disease onset, severe early disease, family history of atopic disease, female sex, low income, black race, and filaggrin mutations have all been associated with more active or prolonged disease. Recent data also suggest the skin microbiome appears to be different in both lesional and nonlesional skin between young children and teenagers/adults with AD. There is little consensus, however, about the causes of disease onset or progression, and there are few studies examining factors that result in long-term or permanent disease remission.

Hypothetical example illustrating the long-term course of AD.

Some investigators have suggested that there may be phases through which individuals are likely to pass, including the development of “autosensitization” and eventually, chronic “autoimmune” disease. Whether eczema predisposes to asthma and allergies, a phenomenon termed the “atopic march,” is also a matter of active debate. Furthermore, it is unclear whether treatment of AD might affect the long-term clinical course or prevent the development of comorbid conditions, although there is some limited evidence to suggest that good control of eczema may have beneficial effects on respiratory disease as well. More data are needed to understand whether the onset and persistence of AD symptoms are part of a causal pathway to progressive disease, or whether barrier and immune dysfunction are always present and symptoms simply emerge when an individual encounters triggers throughout life.

Challenges to studying the long-term course of atopic dermatitis

The chronic and episodic nature of AD renders it particularly challenging to study. We discuss epidemiologic concepts and their application to AD in the following sections and in Table 1 .

Table 1

Methodological considerations for studying the long-term course of atopic dermatitis

Concept	Considerations	Recommendations
Incidence	Must be chronic to meet most diagnostic criteria	Specify minimum duration of symptoms required for diagnosis (4 weeks has been proposed)
Prevalence	Dependent on time period and definition	Specify method of ascertainment (ie, physical examination vs self-report) and definition used
Remission/Persistence	Dependent on length of follow-up and method of detection	Avoid using these terms; specify age of patient and duration of follow-up without treatment and/or symptoms
Flare	Dependent on patient’s baseline; difficult to ascertain exact duration	Clearly define; delineate disease activity from disease severity; consider combination of a patient-reported outcome and a severity score or behavioral measure such as ‘escalation of treatment’
Long-term control	No consensus on measurement	Clearly define; consider use of well-controlled weeks

Only gold members can continue reading. Log In or Register to continue

Share this:

• Click to share on Twitter (Opens in new window)
• Click to share on Facebook (Opens in new window)

Related

Related posts:

Atopic Dermatitis: A Heterogeneous Disorder Public Health Burden and Epidemiology of Atopic Dermatitis Adult-Onset Atopic Dermatitis Special Considerations for Therapy of Pediatric Atopic Dermatitis Management of Atopic Hand Dermatitis Adjunctive Management of Itch in Atopic Dermatitis

Stay updated, free articles. Join our Telegram channel

Join