Infants who have early transient wheeze in the first two years of life have a reduced risk of atopic disease and asthma in later childhood and adolescence, a Victorian study has found
The findings that early transient wheeze is a benign condition that may even be protective against allergy and asthma can be a reassuring message to parents with wheezing infants, according to researchers from the University of Melbourne.
They say their findings, from the long running Melbourne Atopy Cohort of children at high risk of allergic disease, suggest that infant wheeze may often be a sign of viral infections that promote protective immune responses in later life as per the ‘hygiene hypothesis’.
In the latest analysis of 620 children in a high-atopy risk birth cohort, they found that those who had later and more persistent wheeze between the ages of two and seven were up to five times more likely to have adverse allergic outcomes up to 18 years compared to non-wheezing infants.
In particular, children with the “Intermediate Onset wheeze” phenotype were most likely to develop eczema, hay fever, and sensitisation to allergens such as peanuts, milk and house dust mite at the ages 12 and/or 18 years.
Children who had more persistent wheeze were also more likely to have higher fractional exhaled nitric oxide (FeNO) levels at 12 and 18 years of age – a measure of eosinophilic airway inflammation.
However in a novel finding, the “early transient wheezers” had reduced risks of hay fever (Odds Ratio 0.57) and eczema (OR 0·44 ) and sensitisation (OR 0.59), along with lower FENO levels when compared with “never/Infrequent wheezers.”
The researchers said their novel findings may have arisen because – unlike other studies – the Melbourne Atopy Cohort had rigorous prospective recording of infant wheeze at four weekly intervals in the first year of life, and may have detected milder phenotypes.
They said the findings had important clinical implications that would help clinicians determine whether early wheezers are likely to be transient or become persistent.
“Identification of children with early transient wheeze may lead to reduction in potentially unnecessary treatment with possible side effects,” they wrote in Pediatric Allergy and Immunology
“Our findings into early adulthood suggest that … “Early Transient wheeze” is not only a benign condition, as suggested by our previous work, but is associated with protection against subsequent allergic disease and sensitisation,” they concluded.
“Early transient wheeze may indicate the presence of childhood viral infections that are potentially protective against allergic disease through Th1 immune mechanisms … [and] the finding that transient wheeze may be protective for future allergic disease and atopy may be a reassuring message to parents with wheezing infants and young children.”
The five wheezing patterns identified from 23 recordings from the age of four weeks to seven years were: “Never/infrequent wheeze” 47 % (n=290); “Early Transient wheeze” 26%(n=160); “Early Persistent wheeze” 5% (N=33); “Intermediate Onset wheeze” 19% (n=115); and “Late Onset wheeze” 3% (n=33).