Published Online June 27, 2014
The factors responsible for changing trends in asthma incidence have not been completely identified. Previous cross sectional studies of asthma rates have grouped together children of all ages. However, it is possible that observed changes over time in asthma incidence are age dependent. No previous studies have examined changes in the age of asthma onset over time using longitudinal methods.
In an article recently published in The Journal of Allergy and Clinical Immunology (JACI), Radhakrishnan and colleagues used health administrative data housed at the Institute for Clinical Evaluative Sciences to examine trends in age at asthma diagnosis among children in Ontario, Canada. Multiple consecutive birth cohorts of children born between 1993 and 2000 were observed until age eight for the development of asthma. The proportion of children who were hospitalized at the first diagnosis of asthma was also examined over time.
The authors found that the average age at asthma diagnosis has decreased over time. Furthermore, there was an increase in the incidence of asthma among children less than age three but a stable rate of new asthma cases among children older than age three. There was also an increase in the proportion of children less than age three who were hospitalized at first asthma diagnosis.
These findings suggest that the increased incidence of asthma observed over time in children is primarily explained by an increased burden of preschool asthma and is not confined to mild cases. As the rates of asthma hospitalization among preschool children remain high, strategies to prevent morbidity in this youngest age group are still needed, including early initiation of controller medications as well as development of new treatments to target this youngest age group.
The Journal of Allergy and Clinical Immunology (JACI) is an official scientific journal of the AAAAI and is the most-cited journal in the field of allergy and clinical immunology.