Continuing increase in respiratory symptoms and atopy in Aberdeen schoolchildren
BMJ 1996; 312 doi: https://doi.org/10.1136/bmj.312.7022.34 (Published 06 January 1996) Cite this as: BMJ 1996;312:34
- Correspondence to: Dr Russell.
- Accepted 30 August 1995
The prevalence of childhood asthma seems to be increasing,1 although at least part of the reported increase may reflect previous underdiagnosis. In an earlier paper we described the increase in respiratory symptoms and diagnosed atopy that occurred in Aberdeen schoolchildren during the 25 years to 1989.2
Subjects, methods, and results
In May 1994, through the schools, we distributed questionnaires with an explanatory letter to the parents or guardians of the 4197 children attending primary clases 5, 6, and 7 in each of the 34 schools lying within the boundaries of the city of Aberdeen as they existed in 1964 and which had also provided the population base for the 1964 and 1989 studies. The questionnaire included items on respiratory symptoms (wheeze, shortness of breath, night cough) and diagnoses of atopy (asthma, eczema, and hay fever). The questionnaires were collected at the end of the week in which they were distributed, and a repeat questionnaire was issued to non-responders, again through the class teacher. A third questionnaire was sent to those parents who failed to respond to the first reminder, this time by post. Our protocol, including the questions and the explanatory letter, was identical to that followed in 1989, except that the questionnaires were printed on green rather than white card.
A total of 4034 (96.1%) questionnaires were returned, relating to 2013 boys and 2021 girls, 3770 (89.8%) with no reminder, 177 (4.2%) after the first reminder, and 87 (2.1%) after the postal reminder. There were no significant differences between the responses to the questionnaire in these three groups, and the results presented are based on the total population of 4034 responders.
The mean (SD) age of the children was 10.6 (0.89) years (range 8.5 to 13.9). There were significant rises in the prevalence of wheeze, attacks of wheeze occurring more often than three monthly, attacks of shortness of breath in the past year, attacks of shortness of breath occurring six or more times in the past year, and of persistent night cough (table). The proportion of children with a reported diagnosis of asthma roughly doubled between 1989 and 1994, with a smaller increase for eczema and no change for hay fever.
Changes in the prevalence of respiratory symptoms and diagnoses of atopic disorders 1989-94
Comment
After a detailed review of published reports, Anderson suggested that the prevalence of wheezing illness might have reached a plateau in the mid-1980s.3 Our study, performed on children in the same classes of the same schools during the same month as the 1989 study, suggests that, at least in Aberdeen, the prevalence of childhood wheezing illness is still increasing. Increased professional and public awareness of asthma might be responsible for some or even all of the increased diagnosis of asthma but is unlikely to explain the increase in reported symptoms; not only is the prevalence of wheeze increasing, but its apparent severity is also increasing, with more children experiencing more frequent attacks of wheeze and shortness of breath.
This study was not designed to elucidate possible causes for these changes, which remain the subject of speculation. Having previously shown a high prevalence of wheezing illness among schoolchildren in the Highlands of Scotland,4 we find it difficult to believe that outdoor air pollution is a major factor in initiating the asthmatic state; we are inclined to support alternative hypotheses, such as dietary deficiency of antioxidants,5 or changes in indoor environment or life style. The frequency with which eczema is diagnosed has also risen, and we continue to believe that any explanation for the increasing prevalence of asthma should also explain the increasing prevalence of other atopic disorders.2
We thank Mr James Graham, director of education, for permitting access to the schools and the many head teachers, teachers, parents, and pupils whose efforts ensured the success of this project.
Footnotes
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Funding Allen & Hanburys.
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Conflict of interest None.