Transcript JAMA Pediatrics Journal Club Slides: Peanut or Tree Nut Allergy in Offspring Frazier AL, Camargo CA Jr, Malspeis S, Willett WC, Young.

JAMA Pediatrics Journal Club Slides:
Peanut or Tree Nut Allergy in Offspring
Frazier AL, Camargo CA Jr, Malspeis S, Willett WC, Young MC.
Prospective study of peripregnancy consumption of peanuts or tree
nuts by mothers and the risk of peanut or tree nut allergy in their
offspring. JAMA Pediatrics. Published online December 23, 2013.
doi:10.1001/jamapediatrics.2013.4139.
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Introduction
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Background
– The etiology of the increasing prevalence of peanut or tree nut (P/TN)
allergy in children is unknown.
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Study Objective
– To examine the association between peripregnancy consumption of
P/TN by mothers and the risk of P/TN allergy in their offspring.
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Methods
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Study Design
– Prospective cohort study.
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Setting
– United States, in children born between January 1, 1990, and December
31, 1994.
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Patients
– Maternal diet was recorded as part of the ongoing Nurses’ Health Study
II (n = 116 430). Their offspring are participants in the ongoing Growing
Up Today Study 2 (n = 10 907). After exclusions (eg, nonresponse to our
2009 food allergy survey), the analytic cohort comprised 8205 children.
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Methods
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Outcomes
– Self-report of a physician-diagnosed P/TN allergy, which then was
confirmed by medical record review.
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Limitations
– 45% of the maternal diets were reported during pregnancy; 76% within
1 year of pregnancy.
– Self-reported diagnosis; not food challenge.
– History of food allergies in the father were not recorded or accounted
for in the analysis.
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Results
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Main Study Findings
– Authors identified 140 cases of P/TN allergy.
– Incidence of P/TN allergy was lower among children of 8059 mothers
who consumed more P/TN in their peripregnancy diet (≥5 times vs <1
time per month: odds ratio = 0.31; 95% CI, 0.13-0.75; P trend = .004).
– In contrast, a nonsignificant positive association was observed in
offspring of 146 mothers with P/TN allergy (Ptrend = .12).
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Comment
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Animal studies have shown decreased food allergy in offspring of mothers
consuming food allergen during pregnancy and lactation.
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Human studies have shown inconsistent results, either increased
sensitization or no effect.
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To our knowledge, this is the first human study to indicate that maternal
P/TN consumption during the peripregnancy period is associated with
reduced P/TN allergy in offspring.
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Comment
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Strengths of Study
– Maternal history of P/TN consumption was obtained at time of, or within 6
months of, the pregnancy, which improves accuracy of quantitative
results relative to recall.
– Questionnaires were completed more than a decade before the start of
this food allergy study, reducing recall bias that limits retrospective
studies.
– Recruitment of subjects was not based on atopic history or a genetically
high-risk population, increasing the generalizability of study results.
– All cases of self-reported physician-diagnosed food allergy were
independently reviewed by a board-certified allergist and a board-certified
pediatrician. Based on the strength of evidence (medical records,
including skin prick and specific IgE test results), confirmation codes were
assigned to each case. Our conclusions are likely to be based on true
P/TN allergy as opposed to food sensitization alone.
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Comment
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Limitations
– Dietary questionnaires were not specific for the actual dates of the
pregnancy but were chosen closest to the child’s date of birth: 45%
were completed during pregnancy; 76% within 1 year of the pregnancy.
– The study examined maternal history only; potential paternal effects on
the development of P/TN allergy were not investigated.
– Potential confounding factors:
• Mothers consuming more P/TN were more likely to consume more
fruits and vegetables (high levels of antioxidants have been
associated with decreased atopy) and more likely to introduce P/TN
to the child’s diet at an earlier age (may induce oral tolerance).
• These variables were controlled for in the multivariable models, and
they did not materially affect the results.
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Contact Information
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If you have questions, please contact the corresponding author:
– Michael C. Young, MD, Division of Immunology, Fegan 6, Boston
Children’s Hospital, 300 Longwood Ave, Boston, MA 02115
([email protected]).
Funding/Support
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This work was supported by Food Allergy Research and Education, New
York, New York.
Conflict of Interest Disclosures
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Dr Young receives royalties from Fair Winds Press for his book titled The
Peanut Allergy Answer Book, third edition. No other disclosures were
reported.
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