Childhood allergies show increased adulthood asthma risk

Children who have the skin condition eczema, particularly with hay fever, are nine times more likely to develop allergic asthma in their adulthood, a new study reveals.

Australia has one of the highest levels of eczema, with nearly one in five children aged six to seven affected.

Pamela Martin is an epidemiologist, completing her PhD at the University of Melbourne and the Murdoch Children’s Research Institute. She recently published a paper investigating the link between childhood allergies to asthma later in life with some interesting results.

“We found that study participants who had childhood eczema and hay fever were at a higher risk of having allergic asthma later in life. This has enormous implications for the potential treatment of childhood allergies before they grow into further problems later down the track,” she says.

Researchers now estimate that up to 30 per cent of current allergic asthma in adults could be attributed to a history of childhood eczema and hay fever.

“This is the first study to distinguish between allergic and non-allergic asthma and their occurrence after childhood eczema and hay fever, as part of a sequence of allergic illnesses dubbed the ‘atopic march’,” Ms Martin says.

Associate Professor Shyamali Dharmage, a senior co-author on the paper from the University of Melbourne’s School of Population Health says currently few interventions are trialled to halt this march from childhood allergies to asthma.

“If successful strategies to stop the ‘atopic march’ are identified, this could ultimately save lives and health care costs related to asthma management and treatment,” she says.

Ms Martin was able to undergo her investigations in part via the resources of the Tasmanian longitudinal Health Study (TAHS), the largest of its kind in the world.

In the longitudinal study, 8500 seven-year-old children, their parents and siblings (total 45,900 participants) were assessed about their allergies and environment in 1968. The seven-year-old children were subsequently followed up with the most recent study completed in 2004 when they were 44 years old.

The TAHS is a collaborative research project between the University of Melbourne, the Menzies Research Institute and Monash University. Associate Professor Dharmage is the principal investigator.

Published online in the Journal of Allergy and Clinical Immunology, the latest study reported on evidence from clinical investigations of around 1400 adult participants in the fifth decade follow-up of TAHS.

Ms Martin analysed survey and skin prick testing data, which measures allergic sensitivities to pollens, dust and animals, collected in the clinical study for evidence of childhood eczema and hay fever leading to types of adult asthma.

“Eczema is a very common disease in childhood and one of the most common childhood conditions presented to doctors – it was its connections to other allergies such as asthma which intrigued me, “ she says.

A global medical debate as to whether eczema was connected to other allergies was what drew Ms Martin to embark upon her PhD. Using the TAHS data, she was able to investigate different forms of asthma, which had not been available before in population-based studies.

“By splitting asthma into allergic and non-allergic forms of the condition, we were able to see a link between those participants who had eczema earlier in life were at a higher risk of having allergic asthma into adulthood,” she says.

There are many types of asthma that can present in adulthood. “To the patient, they can all feel the same but the underlying inflammation is different. Hence they may have different causes.

“This study is the strongest evidence that we have to date that gives good reason to investigate the potential for treating allergies in children for the prevention of asthma in the future.”

Another aspect to her PhD thesis is to investigate how eczema might relate to food allergies, working with Associate Professor Katie Allen in the Health Nut Study at the Murdoch Children’s Research Institute.

“This research may help us to better identify who is at risk of childhood food allergies, which are a huge concern to parents,” Ms Martin says.

Associate Professor Katie Allen said investigation into whether severity and timing of eczema onset increases the risk of infantile food allergy will provide important clinical predictors for targeting children early in life.

“Importantly we hope it will help to prevent unnecessary cases of anaphylaxis – the most severe type of food-related allergic reaction,” she says.