Treating hay fever prevents asthma in kids

NEW YORK (Reuters Health) - Children who suffer from hay fever, due to allergies to mold or pollen, are less likely to go on to develop asthma if they get immunotherapy to combat their sensitivity to allergy-triggers, researchers say.

Immunotherapy aims to build up tolerance to substances that set off allergic reactions by slowly exposing the affected person to gradually increasing doses of the allergen, either by injections or administration under the tongue. The process can take months or years to achieve full desensitization.

The current study, a follow-up of the Preventive Allergy Treatment (PAT) study, showed that specific immunotherapy for children with hay fever, or "seasonal allergic rhinoconjunctivitis," helps prevent the development of asthma for up to 7 years after treatment ends.

The PAT study investigated whether the effects of 3 years of immunotherapy persist in children with seasonal allergic rhinoconjunctivitis caused by birch and/or grass pollen allergy as they grow up. The results at 10 years after the start of treatment are reported in the medical journal Allergy.

Dr. L. Jacobsen from ALK-Abello, Horsholm, Denmark and colleagues found that, among 117 children who were free of asthma at the start of the study, those given immunotherapy were 4.6 times more likely than those treated with an inactive "placebo" to remain free of asthma during the 10 years of follow-up.

Of 53 patients given placebo, 24 developed asthma, whereas among the 64 patients in the immunotherapy group, 16 became asthmatic.

Furthermore, the beneficial effect of immunotherapy in easing allergy symptoms, like runny noses and itchy eyes, also persisted 7 years after completion of 3 years of treatment.

"This 10-year follow-up study demonstrates that specific immunotherapy for 3 years with high-dose standardized allergen extracts shows persistent long-term effect on clinical symptoms after termination of treatment and long term, preventive effect on later development of asthma in children with seasonal rhinoconjunctivitis," Jacobsen's team concludes.

"In this light," they write, "specific immunotherapy should be recognized not only as first line therapeutic treatment for allergic rhinoconjunctivitis but also as secondary preventive treatment for respiratory allergic disease."

SOURCE: Allergy, August 2007.