Cord-blood test predicts kids' allergy odds

A common feature of allergies and asthma is an elevated blood level of a class of antibodies called immunoglobulin E, or IgE. Researchers now report that when a baby is born, high IgE levels in the umbilical cord blood indicate an increased risk of allergies and asthma during childhood.

A previous study showed a link between cord-blood IgE levels and the risk of allergy and asthma in the first year of life. The current analysis of the same group of children extends this observation by showing that an increased risk is still apparent up to 10 years of age.

The study involved 1358 children who were born between 1989 and 1990 and had cord-blood IgE levels measured. Skin-prick testing for allergies was performed on 981 of these children at age 4 and on 1036 at age 10.

At age 4, about 20 percent of the subjects had allergies and by age 10 this had risen to 27 percent, Dr. W. Karmaus, from Michigan State University in East Lansing, and colleagues report in the medical journal Thorax.

Elevated cord-blood IgE levels approximately doubled the risk of allergies at both 4 and 10 years of age.

Rates of asthma ranged from 10 percent at age 1 and 2 to 15 percent at age 4. Cord-blood IgE levels were not linked to asthma risk at age 1, 2 or 4, but were associated with a 66 percent increased risk at age 10.

"The lack of significance of cord (blood) IgE as a risk factor for asthma early in life may be due to the gradual development of asthma as the cohort aged and the existence of a late onset variety of asthma," the investigators write.

"Further investigations are needed to increase our understanding of the immunological mechanisms responsible for the effect of fetal life events on childhood allergy," Karmaus' team concludes.

SOURCE: Thorax, November 2004.