From atopic dermatitis to asthma.

The cumulative prevalence of atopic dermatitis has been regularly increasing for several decades. Epidemiological studies show that it has doubled in most industrialized countries over the last 20 years, varying between 10 and 20%. The relationships between atopic dermatitis and asthma have remained Vague and subjective for a very long time. However, this review article presents several conclusions. Atopic dermatitis resolves in at least 80 p. cent of cases, especially when it starts at an early age. The appearance of asthma is frequent (20 to 87% of cases), especially when atopic dermatitis starts before the age of 2 years. Maternal smoking increases the risk of asthma in children suffering from atopic dermatitis. Nonspecific bronchial hyperreactivity is observed in 58 to 82% of cases of isolated atopic dermatitis; it is almost constant (up to 95% of cases) when asthma and dermatitis are associated and in the case of early onset dermatitis. Specific bronchial hyperreactivity to house dust mites is present in one half of eczematous patients: the inhalation of house dust mites in patients suffering from atopic dermatitis induces an immediate bronchoconstrictor response and the appearance of dermatitis symptoms in healthy skin and/or deterioration of pre-existing lesions in 45% of cases. The role of sensitization to allergens (respiratory allergens and trophallergens) is underestimated; it is very important during severe extensive atopic dermatitis. Despite a better understanding of the natural history of dermatitis, it is difficult to predict the individual course, hence the importance of regular clinical surveillance with detection of the presence of an obstructive ventilatory disorder and bronchial hyperreactivity. The reduction df the risk of asthma in children and adolescents suffering from atopic dermatitis requires information of the patient and the parents, good occupational guidance and the obligatory reduction of the allergenic load. The preventive benefits of anti-allergic drugs must be better evaluated.