Different age-specific patterns defined the relationships between early daycare, severe airway infection, preterm birth and atopy-related diseases in childhood, according to a study published in Pediatric Allergy and Immunology.
These differences could be used to help identify strategies to prevent or delay atopic diseases, Tadao Nagasaki, of the department of respiratory medicine at the Graduate School of Medicine of Kyoto University in Japan, and colleagues wrote.
The researchers identified 47,015 children born between Jan. 1 and 17, 2001, in Japan. Families were mailed questionnaires when these children were aged 6 months and then again when aged 1.5, 2.5, 5.5, 7, 8, 9, 10 and 11 years.
Between 5.5 and 11 years, prevalence of both asthma (8.6% to 5.4%) and atopic dermatitis (7.8% to 5.9%) decreased linearly. However, the same time span showed a linear increase from 13% to 24% in allergic rhinitis and conjunctivitis.
The researchers found a significant inverse association between daycare attendance and asthma between 5.5 years (adjusted OR = 0.77; 95% CI, 0.69-0.86) and 9 years (aOR = 0.85; 95% CI, 0.75-0.97), although this reduction lost significance after 10 years (aOR = 0.91; 95% CI, 0.79-1.04). Throughout childhood, there were also protective associations between incidence of allergic rhinitis/conjunctivitis and early daycare and older siblings.
There was no association between older siblings and asthma, but the researchers found that a history of hospitalization due to cold/bronchitis/bronchiol increaseditis/pneumonia risk for asthma across ages, and for allergic rhinitis/conjunctivitis at 8 years (aOR = 1.13; 95 % CI, 1-1.27), 9 years (aOR = 1.13; 95% CI, 1.01-1.27) and 11 years (aOR = 1.19; 95% CI, 1.06-1.32).
Plus, preterm birth was a risk factor for asthma between 7 and 11 years, with aORs in those age groups ranging from 1.29 to 1.37, and rapid weight gain was a risk factor at 9 years (aOR = 1.21; 95% CI, -1.04 1.4). Additionally, the researchers found allergic preterm increased risk for rhinitis/conjunctivitis at 8 years (aOR = 0.84; 95% CI, 0.73-0.97) and rapid weight gain increased risk for allergic rhinitis/conjunctivitis at 5.5 years (aOR = 1.15; 95 % CI, 1.04-1.28).
When looking at the incidence of asthma with allergic rhinitis/conjunctivitis, early daycare and older siblings appeared protective at 5.5, 7, 8, 9 and 11 years, but a hospitalization due to cold/bronchitis/bronchiolitis/pneumonia increased risk throughout childhood.
Researchers observed additional risks for asthma with allergic rhinitis/conjunctivitis associated with preterm birth at 7 years (aOR = 1.38; 95% CI, 1.03-1.87) and rapid weight gain at 8 and 10 years.
At 5.5, 7, 8 and 10 years, early daycare and older siblings were risk factors for atopic dermatitis.
Noting these different patterns in factors that may influence the development of atopy-related diseases during childhood, the researchers called for further cohort studies to determine whether the prevention or delay of early life influences could modify the progression of these diseases.