Background: Atopic dermatitis (AD) is common in the population, and studies have shown that the disease is on the increase. Studies based on hospital records reflect selected populations and may miss less severe cases of AD, and the use of self-reported questionnaires has the drawback of recall bias.
Objectives: To investigate some possible factors influencing recall bias when questionnaires are used to establish the prevalence of childhood eczema in an adult population.
Methods: A questionnaire regarding past and present eczema was sent to 557 cases (with signs suggesting the diagnosis AD) and 554 matched controls (subjects lacking signs of AD) born during 1960-1969 and identified in school health medical records. Cases and controls were aged 31-42 years at the time of the study and 70.5% returned the questionnaire.
Results: Of 403 cases, 29% did not report childhood eczema in the questionnaire. There was a difference between those who did recall their childhood AD (remembering group, RG), and those who did not (forgetful group, FG) in who had documented the diagnostic signs in the school health records. In the RG the signs were reported by both parents and school health personnel in 51% of cases, and in the FG this was true of only 16%. The RG had a higher prevalence of eczema after 15 years of age and of hand eczema. The RG also reported more visits to physicians after the age of 15 years and more time taken as sick leave due to eczema.
Conclusions: Several factors influence how well people remember their AD in childhood. These factors include disease activity in adult life, disease severity, and who noticed the eczema in childhood.