Daycare, older siblings, preterm birth yield varied risks for childhood atopic diseases
Click Here to Manage Email Alerts
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 also were 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/bronchiolitis/pneumonia increased 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 preterm birth increased risk for allergic 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.
Perspective
Back to Top
It is important to look for the risk factors for atopic diseases. Why are they rising? This is a large longitudinal study with 47,000 kids. The researchers followed them for a long time, and their findings are consistent with what other people have found.
Early infections are probably protective. That is why going to daycare, being around other people and having older siblings are all part of the hygiene hypothesis. You need to be around other people to get the appropriate number of good germs. That is one of this study’s big findings.
Another is that preterm birth is a risk factor, probably due to lots of different things. Premature lungs are likely a risk factor by themselves for asthma because they have a disrupted barrier.
These findings are all consistent with the hygiene hypothesis. They also are confirmatory and along the same lines of other studies.
This is what we see in practice. Certain things are protective. It gets complicated because there is a genetic component too. As allergists, we always get a bias, because we see people who already have allergies. We see their siblings, and their siblings have asthma. Our patients have genetic risk factors. In a general population, this is very consistent with what we have seen in other research studies.
This study identified three risk factors for asthma early on — premature birth, early infection and rapid weight gain. If you have patients who were premature or obese or were admitted to the hospital for respiratory infection early in their lives, that probably is going to be a risk factor for asthma.
But we do not know if that initial hospitalization by itself causes asthma or if these people were predisposed to these first infections. We all get respiratory syncytial virus (RSV). Maybe that RSV leads these people to be hospitalized, whereas someone who is not at risk for asthma would not be hospitalized. There is a little controversy in that issue right now. Does infection cause asthma, or is it just a marker?
But from a clinical perspective, these findings tell you that these are the people you should look for. You can’t tell people to have more siblings. But you can tell them that preschool may be a good thing and to send their kids to pre-K.
There are still some important questions to answer. What in daycare is different? What is so different about having multiple siblings? Are these patients more exposed to more colds early on? Is that the issue? Or is it a change in their microbiome? These are important questions to ask.
Collapse
Read more about
Click Here to Manage Email Alerts