Doctors have devised a way to predict which children who wheeze will go on to develop asthma.
Doctors could predict which children are at risk of asthma
Around one in three small children suffers from wheezing but researchers estimate just four out of 10 of these are at risk of developing asthma.
Writing in the European Respiratory Journal, they describe how they devised a predictive scale which doctors will be able to use to estimate risk.
Children in danger could then be kept away from potential asthma triggers.
Wheezing, caused by narrowing of the airways, can be very distressing for parents and children.
In many cases it disappears completely after a couple of years.
But it is important for doctors to be able to distinguish which children are at risk, and therefore need early treatment.
Researchers from St Mary's Hospital on the Isle of Wight, studied over 1,000 boys and girls from birth to the age of 10.
They were grouped at birth according to whether there was a family history of allergies, if they had a pet, if their parents smoked and their family's socioeconomic background.
The children were examined at age one, two, four and 10, when parents were also asked about allergy problems or asthma symptoms.
The children were also screened to see if they had wheezing, asthma, upper respiratory infections, rhinitis, eczema or food allergies at the time of the test.
At age four, they were also given a skin-prick test to see if they had any of the most common allergies, including dust mite, animal fur, pollen, milk, eggs or peanuts.
By the age of 10, 40% of the children (417) had experienced wheezing at some point in their lives.
Of those 336 had started wheezing before the age of four. Most had "transient wheezing", which did not last. Only a third of this group (125 children) still had a problem at the age of 10.
The researchers found four major characteristics which distinguished the group with persistent wheeze: -
- They were 2.2 times more likely to have a parent or sibling with asthma,
They were six times more likely to test positive for common allergies than those with transient wheezing,
They were twice as likely to have had a chest infection by the age of two,
They had had fewer upper respiratory tract infections by the age of one than the other group.
Other factors such as maternal smoking at birth, having cats and dogs in the household and whether the child was breastfed also had an influence.
Based on their findings, the team have been able to devise a scale which doctors can use to predict which children will have long-term problems.
The team now hope to follow the children until they are 16.
Dr Hasan Arshad, who led the research, said: "By asking just three questions (on family history of asthma, chest infections and past rhinitis) and conducting a simple and safe skin-prick test, the general practitioner or paediatrician can easily identify young children whose wheezing is likely to turn into respiratory allergy.
"This could allow us to develop a more precise risk scale than the one we are publishing now."
Dr Richard Russell, a consultant chest physician at Wexham Park Hospital in Berkshire, told BBC News Online the study was significant because it had looked at a whole population of children, rather than concentrating on at-risk groups.
He added: "Only a minority of children wheeze, but we might be able to identify better than before those who will develop childhood asthma.
"The risk scale is not very helpful, but it does flag up the fact that there is an influence of family history, infectious agents and smoking.
"It also takes away things such as cats, which don't seem to be causing a problem."