Children who become sensitive to allergens, such as cat hair, and suffer from wheezing in their first three years of life are prone to developing asthma, according to an Article in this week’s issue of The Lancet.
Between birth and school age some children who experience persistent wheezing lose their lung function and develop asthma but others do not. The factors that determine which children develop asthma have been unclear until now.
In the study Sabina Illi (University Children’s Hospital, M?, Germany) and colleagues investigated the role of allergen exposure in early life and sensitisation to allergens on the development of lung function and asthma. The investigators enrolled over 1300 children, born in 1990, into the study. Around 500 of the children were found to have known risk factors for allergen sensitivity at birth. These risk factors are high level of IgE antibodies** in umbilical cord blood and/or at least two first degree relatives with allergen sensitivity.
From birth to age 13 the researchers interviewed parents about their child’s asthma and measured levels of IgE antibodies in the children. They found that 90% of children who experienced repeated wheezing but were not susceptible to allergies lost their symptoms at school age and retained normal lung function at puberty. However, the children who had repeated wheezing and developed sensitivity to allergens in their first 3 years of life were more likely to develop a loss of lung function and asthma. The researchers also found that exposure to high levels of allergens contributed to development of asthma.
Previous studies have shown that the reducing children’s exposure to allergens fails to prevent asthma. The authors therefore suggest that future studies look at whether giving wheezy, allergy susceptible children preventive treatment (inhaled corticosteroids) early on can reduce their chance of developing asthma at school age.
Dr Illi states: “Given the good prognosis for non-atopic [non-allergy susceptible] wheezing children, the need for these individuals to continue to take inhaled corticosteroids on a regular basis should be re-assessed.”
*Asthma is a condition that affects the airways that carry air in and out of the lungs. When people with asthma are exposed to certain triggers such as exercise, allergen exposure, and viral infections their air passages become narrow and inflamed. This reaction causes the symptoms of asthma, which are typically coughing, wheezing and difficulty breathing. Reduced lung function is also a feature of asthma, which becomes apparent at school age.
**IgE antibodies are produced by the immune system in response to allergens.
Revision date: July 3, 2011
Last revised: by Janet A. Staessen, MD, PhD