Clinical Characteristics of Peanut-Allergic Children: Recent Changes
Authors: Sicherer Scott H. 
Published: October 2008

Green TD, LaBelle VS, Steele PH, et al. Pediatrics. 2007;120(6):1304–1310

PURPOSE OF THE STUDY. To determine if patients seen in a referral clinic are experiencing initial allergic reactions to peanuts earlier, compared with a similar population profiled at a different medical center 10 years earlier.

STUDY POPULATION. The primary study group comprised children evaluated and diagnosed as having peanut allergy in the Duke University pediatric allergy and immunology clinic in North Carolina between July 2000 and April 2006.

METHODS. This was a retrospective chart review with some follow-up telephone calls to determine missing data. Food-allergy diagnoses were based on clinical and laboratory data or oral food-challenge results. Results were compared with those previously published from a referral practice at Johns Hopkins Hospital in Baltimore, Maryland, from a decade earlier.

RESULTS. One hundred forty patients (70 born between 1988 and 1999 and 70 born between 2000 and 2005) were included in the study. Eighty-three percent reacted on their first known exposure to peanut. The median age of first peanut exposure was 14 months, and median age at first reaction was 18 months. This contrasts to the study at Johns Hopkins Hospital between 1995 and 1997, in which the median age at first exposure was 22 months and median age at first reaction was at 24 months. Within the Duke University patient group, those born before 2000 were first exposed to peanuts at a median age of 19 months and reacted at a median age of 21 months, compared with first exposure at 12 months and first reaction at 14 months for those born in or after 2000. Most (68%) patients demonstrated sensitization or clinical allergy to other foods (53% to eggs, 26% to cow's milk, 20% to tree nuts, 11% to fish, 9% to shellfish, 7% to soy, 6% to wheat, and 6% to sesame seeds).

CONCLUSIONS. The ages of first peanut exposure and reaction have declined among peanut-allergic children seen in a referral clinic. The decline in the age of first peanut reaction seems to be attributable to earlier exposure.

REVIEWER COMMENTS. Assuming there is not a referral bias driving these results between the 2 sites or within the Duke University site over time, there are 2 ways to interpret these data: either peanut-allergic reactions are occurring earlier because we are feeding peanut earlier, or peanut reactions will occur in those disposed to it whenever they are fed it, whether at age 1 or 2 years. I am going to argue for the latter explanation on the basis of there being no difference in the percentage who reacted at first exposure or in the time between first exposure and first reaction. We have much more to learn regarding the influence of timing of feeding an allergenic food such as peanut; studies on this unresolved issue are underway. Many factors may play a role, but it is intriguing that, counter to what is implied in this study (that early exposure may be bad and related to an apparent rise in peanut allergy), peanut allergy is uncommon in countries that feed peanut earlier (eg, Israel). Other important messages in this study are that (1) sesame allergy is prominent, and (2) if you see egg or milk allergy, consider the possibility that peanut allergy is lurking.