Diagnosis of atopic dermatitis relies strongly on clinical presentation and is typically made through an extensive history and physical examination (Avena-Woods, 2017). Several classification criteria have been developed, but the Hanifin and Rajka criteria originally developed in 1980 remain the most widely used worldwide (Wollenberg et al., 2018).
The original criteria developed by Hanifin and Rajka are thorough, requiring 3 of 4 basic features (pruritus, typical morphology and distribution, chronic or chronically relapsing dermatitis, personal or family history of atopy) and at least 3 of 23 minor features to be met (Hanifin & Rajka, 1980). While comprehensive and validated, the extensive criteria make their application difficult in everyday clinical practice. Various revisions have been developed to aid using them in clinical practice including those developed by the UK Working Party who narrowed the criteria down to needing 1 mandatory and 5 major features to be met. These criteria have no requirement for laboratory testing and have been validated in various populations, however, they cannot be applied to very young children (Williams et al., 1994; Williams et al., 1996; Gu et al., 2001; De et al., 2006).
To address this limitation of the UK Working Group version, and to make the criteria more streamlined, the American Academy of Dermatology Consensus Conference proposed a further revision (Table 4) (Eichenfield et al., 2003). This version of the criteria has not been validated, but they were deemed suitable for diagnosing atopic dermatitis in patients of all ages (Avena-Woods, 2017).
Table 4: American Academy of Dermatology consensus conference revision of the Hanifin & Rajka diagnostic criteria for atopic dermatitis (Eichenfield et al., 2003).
At present, no laboratory biomarkers have been identified to aid with the diagnosis of atopic dermatitis. The elevation of total- or allergen specific IgE in serum or the use of skin tests to detect IgE-mediated sensitisation has been proposed. However, this feature is not present in all patients and has led to the terms ‘intrinsic’ (non-IgE-associated) and ‘extrinsic’ (IgE-associated) being used to describe these different forms of atopic dermatitis. However, controversy persists around the use of these terms and the practical applications of IgE detection in patients with atopic dermatitis (Wollenberg et al., 2018). Despite variation in IgE levels, it has been shown that intrinsic and extrinsic atopic dermatitis patient groups had similar underlying expression levels of Th2-related genes. This suggests that the underlying pathophysiology of their atopic dermatitis may be more similar than expected (Suárez-Fariñas et al., 2013).
Beyond diagnostic biomarkers, there is a general lack of biomarkers available to support patient stratification and management. In the past, treatment was typically nonspecific and consisted of topical and systemic immunosuppressants. However, many patients failed to respond to treatment leading to concerns among patients. With the advent of targeted biologic therapies in atopic dermatitis, identification of eligible patients who are likely to respond to therapy is now of increased need to reassure patients and avoid costly treatment failure (Thijs et al., 2017).
Numerous studies are currently ongoing looking at a variety of potential atopic dermatitis biomarkers. However, at present none have been shown to be reliable or sensitive enough to support regular clinical use (Avena-Woods, 2017; Wollenberg et al., 2018).