Prevalence, incidence and course of eczema on the hands and forearms in a sample of the general population.

In 1979, the inhabitants of a geographically defined area were examined for skin disorders of the hands and forearms. In 1982 this cohort was invited for re-examination. In persons with eczema, patch testing was performed. Irritant factors were found to play a rôle in 73% of the cases, whereas a contact allergy could be detected in 30%. The most frequent allergens were nickel sulphate (20%), potassium dichromate (6%) and cobalt chloride (4%). In some persons with a definite history of allergy to metals, no positive patch test with nickel, chromate or cobalt could be obtained; other mechanisms may be involved. Significantly more positive patch tests were found among persons with an eczema of longer than 2 years duration compared with persons with eczema present for a shorter period of time, indicating that many cases of eczema are primarily of irritant nature, but later complicated by sensitisation. In 41%, the eczema was healed. A poor healing tendency was observed in those with a combination of irritant and allergic eczema. Relatively few ascribed healing to medical treatment.