SELECTED ARTICLES FROM THE RECENT LITERATURE 2003

10/8/03

Relationship of cough-variant asthma to classic asthma in childhood

Summary
Some children with chronic cough of undetermined cause are considered to have cough-variant asthma (CVA). However, it is unclear what percentage of such children with subsequently manifest classic active asthma. Todokoro et al of the Gumma Univ. School of Medicine in Maebashi, Japan evaluated 100 children with chronic, idiopathic cough. They found evidence of bronchial hyper-reactivity (BHR) to methacholine challenge in 75 of these children, suggesting that they had CVA. After a subsequent follow-up period of ä 3 years, 52 of the 75 children with CVA were located. Classic asthma had been diagnosed in 28 of these 52 children. Chronic asthma was seen more commonly in children with a previous onset of CVA at an earlier age. However, there was no difference in the gender or degree of BHR in those children with CVA who subsequently manifested asthma vs those who did not subsequently exhibit asthma.

Reference
Ann Allergy Asthma Immunol 2003; 90:652-9

Editor's Comments
Chronic cough is a relatively common problem in childhood and CVA is often diagnosed when no other cause can be found. Therefore, it would be important to learn what percentage of such children with CVA actually manifest classic asthma subsequently. Thus, the objective of this study is quite important. However, I have some concerns about study design: 1) the diagnosis of CVA in this study is based strictly on the findings of BHR in a methacholine inhalational challenge. However, it is well known that BHR can be seen in some children without any lower airway symptoms (e.g. - active allergic rhinitis); 2) the authors located only 52 of the 75 children with CVA for follow-up evaluation; 3) the diagnosis of "classic asthma" was based just on the parents being told by some healthcare worker that the child had asthma. One wonders whether such healthcare worker may have been more likely to say a child had asthma if the parents say that a previous evaluation of their coughing child suggested a possible variant of asthma being present. One would have liked to see some objective measurements of airflow to support a diagnosis of asthma.

With these concerns in mind, the findings described above may be quite important. They should stimulate a more objective, complete follow-up evaluation.

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