Does allergy in parents depend on allergy in their children? Recall bias in parental questioning of atopic diseases

Background: A positive atopic family history has proved to be one important risk factor for the development of atopic dis eases in offspring. However, many epidemiologists are concerned about the accuracy and reliability of d ata because responses to questionnaires can be biased for many reasons. Objective: The study investigated whether responses of parents questioned a bout their atopic diseases change depending on the development of atopic sy mptoms in their children. Methods: During a prospective birth cohort study on atopy in children (the Multicenter Allergy Study) parents filled out questionnaires twice within 2 years about their atopic diseases. Differences between the 2 responses wer e examined by log-linear and logistic regression models depending on the di agnosed atopy status of the study children. Results: Mothers tended to report more atopic diseases in the second questi oning than in the first, indicating a nondifferential misclassification Fat hers were influenced by the development of atopic diseases in their childre n: they reported significantly more atopic diseases if the child developed atopic illness with atopic dermatitis. Conclusion: In parental questioning about atopic diseases, a recall bias mu st be considered for the association of atopic family history and atopy In children. Especially in case-control and cross-sectional studies, such misc lassifications can result in biased estimates of prognosis and risk factors .