Atopic dermatitis in infancy

Abstract

Atopic dermatitis is a common disease characterized by a chronic relapsing and itchy rash. Although the first symptoms often occur in the first year of life, the diagnosis may be difficult to make in infants. Data on potential sex-specific variations concerning risk factors and clinical presentation in early life are limited. The aims of this thesis were to study the validity of well-established diagnostic criteria for atopic dermatitis used in infants, and to identify early risk factors, including potential sex-specific variations. The study cohort consisted of infants in the Preventing Atopic Dermatitis and Allergies (PreventADALL) study (n = 2397). Clinical data were collected during pregnancy, at birth and from follow-up visits at 3, 6 and 12 months of age. Both the United Kingdom Working Party criteria and Hanifin & Rajka criteria had several limitations, documenting the difficulties in diagnosing atopic dermatitis during infancy. Applying both sets of criteria and at multiple time points may be useful in clinical research, but not in most clinical settings. Atopic dermatitis in parents increased the risk in offspring, particularly in infants with the same sex as the affected parent. More boys than girls had atopic dermatitis during infancy, and the clinical distribution of eczema differed by sex, indicating possible differential disease mechanisms. In addition, birth by elective caesarean section increased the risk, supporting the benefit of vaginal birth over caesarean section.