Changes in Childhood Atopic Dermatitis Incidence and Risk Factors Over Time: Results From Two German Birth Cohorts

BackgroundAtopic dermatitis (AD) is a common allergic skin disease. We aimed to assess the secular changes in the cumulative incidence of childhood AD and its risk factors over a decade.MethodsWe used data from two methodologically similar cohort studies in Ulm, Germany, the Ulm Birth Cohort Study (UBCS, recruited in 2000/2001) and the Ulm SPATZ Health Study (recruited in 2012/2013). The cumulative incidences of AD as reported by their family physicians and parents up to the age of 4 years were compared by log-rank test across the two cohorts, using propensity score-based weighting to control confounders. We fitted multivariable Cox regression models to estimate hazard ratios and 95% confidence intervals (CIs) for the factors associated with the occurrence of physician- and parent-reported AD and compared the results between the two cohorts.ResultsThe 4-year cumulative incidence (95% confidence interval) of physician-reported AD (27.4% (24.4%-30.5%) in UBCS [2000/2001] vs. 26.4% (22.8%-30.2%) in SPATZ [2012/2013], p = 0.728) and parent-reported AD (14.5% (12.2%-17.0%) in UBCS [2000/2001] vs. 16.7% (14.0%-19.7%) in SPATZ [2012/2013], p = 0.211) remained stable between the two cohorts after propensity score-based weighting. We observed the changes in the association between AD and certain risk factors (e.g., family history of AD and infantile antibiotic use) over the decade, but the results need to be interpreted with caution due to the limited sample size, relatively high attrition rate and demographic differences between the two cohorts.ConclusionsOver the decade, childhood AD incidence remained stable. Further studies are needed to verify whether there is a growing importance of environmental and microbiota-related factors for AD development over time.