Background: Atopic dermatitis (AD) has been highlighted as a likely first step in the 'atopic march', emphasizing the need to define predisposing factors.
Methods: We evaluated AD risk factors and phenotypes in an Asian mother-offspring cohort . We defined three phenotypes of doctor-diagnosed AD based on the time of onset of the disease: early AD occurring within the first 6 months of life, AD occurring between 6 and 12 months and late-onset AD starting after the age of 12 months.
Results: Maternal allergic history was associated with an increased risk of developing early-onset AD (adjusted odds ratio (aOR) 20.46, 95% confidence interval (CI) 2.73-153.15, p < 0.01). Maternal allergic history and attendance at a daycare centre increased the odds of the development of AD between 6 and 12 months (aOR 4.19, 95% CI 1.01-17.45, p = 0.049 and aOR 11.42, 95% CI 1.49-87.50, p = 0.02, respectively). Risk factors associated with increased odds of late-onset AD from 12 months were the consumption of probiotics between the age of 9 and 12 months and antibiotic treatment in the first 6 months of life (aOR 4.32, 95% CI 1.07-17.45, p = 0.04 and aOR 3.11, 95% CI 1.10-8.76, p = 0.03, respectively). Early-onset AD was associated with an increased risk of developing allergic sensitization (aOR 46.51, 95% CI 3.44-628.81, p < 0.01).
Conclusion: We found that early-onset AD was mainly associated with familial factors, while late-onset AD was associated with the consumption of antibiotics or probiotics. The findings support the concept that different phenotypes of AD exist in young children.