Recall bias in childhood atopic diseases among adults in the Odense Adolescence Cohort Study.

Atopic dermatitis (AD) is a common disease in childhood and an important risk factor for the later development of other atopic diseases. Many publications on childhood AD use questionnaires based on information obtained in adulthood, which introduce the possibility of recall bias. In a prospective cohort study, recall bias was evaluated in 1,501 unselected schoolchildren (mean age 14 years) evaluated for the first time in 1995 with a standardized questionnaire combined with a clinical examination and repeated in 2010. The lifetime prevalence of AD was 34.1% including data obtained both during school age and 15 years later, compared with 23.6% including data only from adulthood. The most important factors for remembering having had AD in childhood were: (i) long duration of dermatitis in childhood; (ii) adult hand eczema; and (iii) concomitant atopic disease. Recall bias for childhood AD affected the results of logistic regression on adult hand eczema and is a significant problem in retrospective epidemiological questionnaire studies evaluating previous AD as a risk factor for development of other diseases.