Atopic dermatitis in adults: prognosis and factors of importance for persistence

Abstract: Atopic dermatitis (AD) is a common skin disease with multifactorial aetiology. Elevatedlevels of serum IgE are common in AD patients and IgE antibodies to the yeast Malassezia, amember of the cutaneous microflora, are also common. Many investigations concerning thelong-term prognosis of AD have been performed in children but only a few studies amongadults.The overall aim of the study was to obtain more knowledge about the prognosis of AD inadults and factors of importance for persistence of the disease.Adults with AD examined at 20 years of age or older at the outpatient clinic in theDepartment of Dermatology 25-38 years ago were followed up by a postal questionnairewhen the patients were 45 years of age or older. Analysis of the answers from 833 patientsshowed that the majority of adults with AD continue to have AD as they age. Theprognostically unfavourable factors regarding clearance of AD were, in a logistic regressionanalysis, head and neck AD, siblings with atopic disease, allergy to furred animals, pollenallergy, oral allergy syndrome (OAS), and nickel sensitivity.At clinical examination of randomly selected patients recruited from the questionnaire studythe severity of AD was mainly mild to moderate. The majority had ongoing AD and morethan half had head and neck dermatitis with or without other AD locations. Specific serum-IgE to Malassezia was commonest in those with ongoing AD and head and neck dermatitis.The occurrence of reactivity to Malassezia extract and three recombinant Malasseziaallergens (rMala s1, rMala s5, rMala s6) was measured as specific serum IgE, positive skinprick test (SPT) and atopy patch test (APT) reactions in 132 AD patients in a multicentrestudy. Sixty-seven percent of the AD patients and none of healthy controls (HCs) reacted to atleast one of the Malassezia allergens in at least one of the tests. APT added to the test batteryrevealed a previously overlooked impact of Malassezia hypersensitivity in subgroups of ADpatients without head and neck dermatitis or high total serum IgE. A positive Malasseziaculture was less commonly found in AD patients than HCs. M. sympodialis was the dominantMalassezia species found. No correlation was seen between AD severity, head and neckdermatitis or positive APT reaction and the occurrence of positive Malassezia culture. Noassociation was seen between the Malassezia species cultured from individual patients andtheir serum IgE antibodies to the various Malassezia species.In conclusion, AD persists in a majority of adults with AD. This applies particularly ifunfavourable prognostic factors exist such as head and neck dermatitis and occurrence ofallergies (IgE associated AD). A positive Malassezia culture does not seem to correlate withthe severity of the AD, while the occurrence of IgE antibodies to the yeast Malassezia mightcontribute to the chronicity of AD.