Asthma trends Causes of wheeze and asthma may differ

Abstract

EDITOR, - Two papers report the outcome of childhood asthma in Tasmania1 and Melbourne2 in subjects now in their 30s. We reported a 25 year follow up of schoolchildren in Aberdeen3,4 and think that our findings influence the interpretation of these Australian papers. In the 1964 random community survey that provided the baseline for our study, subjects were classified as having asthma, “wheeze in the presence of respiratory infection” (wheezy bronchitis), or no respiratory symptoms (comparison subjects).5 Review after 25 years of subjects from each group showed that 61% of those who had had asthma in childhood continued to wheeze in adult life, compared with 30% of those who had had wheezy bronchitis; 11% of the comparison subjects had developed wheeze since the original study. Of the subjects who had not had symptoms in childhood who were reviewed by Mark A Jenkins and colleagues, 10.6% had developed symptoms by the age of 29-32,1 a similar percentage to that in our study. Of those who had had symptoms in childhood, 25.6% continued to experience symptoms as adults, a much smaller percentage than we had found. The reason for the difference from our results may lie in the ages at the time of the original studies: the Tasmanian children were identified at age 7, while ours were selected at 10 to 15, when a number of wheezy children would have already grown out of their symptoms. Another explanation may lie in the definition of symptoms in adults: Jenkins and colleagues defined them as the “occurrence of an asthma attack within the previous 12 months,” which is a more stringent definition than that used in our study (wheeze in the past 12 months) or the study by Helmut Oswald and colleagues (wheeze in the past three …