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1.1 The need for diagnostic criteria for atopic eczema
Lack of a disease definition of known validity and repeatability for atopic eczema (AE, or atopic dermatitis) is one of the main reasons why so little is known about the distribution and causes of atopic eczema2. As a result, atopic eczema is often ignored in studies of allergic disease, or if it is mentioned at all, is concealed in one of the results tables without further comment3. This is a pity, because the determinants of total allergic disease (asthma, hay fever and atopic eczema) may be different from the determinants of individual diseases such as asthma.
Unlike internal diseases such as asthma where researchers are still grappling with the relationship between symptoms, disease labels and the results of provocation tests, atopic eczema is directly visible, which makes the development of an objective definition a realistic goal.
Some physicians might regard attempts at defining atopic eczema as an imposition because they are perfectly happy about how they diagnose atopic eczema in individuals. Therein lies the crux of the problem. Diagnosis by physicians based on many years of clinical pattern recognition is entirely appropriate when dealing with individuals, but problems begin when groups of people have to be compared. Whether this be the comparison of different prevalence estimates from around the world, or comparison of therapeutic regimens, it is essential to know that researchers all refer to the same entity. Even experienced physicians seem to miss this point4,5.