June 08, 2001 (The Guardian) - The number of pre-school children who wheeze doubled during the 1990s, according to a study that suggests there may be other causes behind it, rather than simply an increase in allergic reactions.
The study, reported in this week's issue of the medical journal, Lancet, provides worrying evidence of the steep rise in wheezing and asthma among children, which the authors say cannot be easily explained.
The researchers, Claudia Kuehni and colleagues from Inselspital, in Bern, Switzerland, and the Leicester royal infirmary, questioned the parents of 1,650 pre-school children living in Leicestershire in 1990, and the parents of a further 2,600 under-fives in 1998.
They found that all types of wheezing had increased, not just the atopic kind (that arising from an allergic reaction) but the type which is classified as viral because of being linked to colds.
Over the eight years, the proportion of children reported to have had a wheeze rose from 16% to 29%. Diagnoses of asthma rose from 11% to 19%.
The percentage being treated for wheeze rose from 15% to 26% and those admitted to hospital with a chest complaint, such as wheezing, asthma or bronchitis, rose from 6% to 10%. The increases occurred among children who had a wheeze associated with a viral cold (up from 8.7% to 19.3%) and among those with the classic asthma pattern of wheezing triggered by more than one thing (up from 6% to 10%).
During the eight years, said the authors, some of the factors that might have been thought to account for wheezing, such as passive smoking, gas cooking and household pets, had declined and so could not be responsible for the increases.
There are other social and environmental factors that have altered over time, they say, but these did not feature in the questionnaire given to the parents.
"Diet has changed substantially in the UK during the past 25 years, with a decreasing intake of antioxidants, namely ascorbic acid [vitamin C]," said the research team. "Other factors being discussed as possible promoters of wheezing disorders, but not necessarily atopy, and that have changed in past decades, include exercise patterns and obesity, the change from the use of aspirin to paracetamol as the main paediatric antipyretic [a drug to counter fever] and some air pollutants."
The researchers said the results had nothing to do with an increased awareness of asthma and wheezing, which might be thought to lead parents to report it more readily now. If that were the case, then the wheezes reported would be likely to be less severe - but they were not.
The researchers said they planned further research -such as measuring allergic reactions and lung function - when the children in the groups were a little older.
One of the authors of the report, Mike Silverman, from the Leicester royal infirmary, said: "If verified, our findings would imply that a fundamental change in pulmonary responsiveness to environmental triggers has occurred over the past years in young children in the UK."
