Eczema in early childhood, sociodemographic factors and lifestyle habits are associated with food allergy: a nested case-control study.
BACKGROUND
Studies suggest an increase in food allergy prevalence over the last decade, but the contributing factors remain unknown. The aim of this study was to evaluate the association between the most common food allergies and atopic history, sociodemographic characteristics and lifestyle habits.


METHODS
We conducted a case-control study nested within the SPAACE study (Surveying Prevalence of Food Allergy in All Canadian Environments) – a cross-Canada, random telephone survey. Cases consisted of individuals with probable food allergy (self-report of convincing symptoms and/or physician diagnosis) to milk, egg, peanut, tree nut, shellfish, fish, wheat, soy, or sesame. Controls consisted of nonallergic individuals, matched for age. Cases and controls were queried on personal and family history of atopy, sociodemographic characteristics and lifestyle habits. Multivariate logistic regression was used to evaluate the association between atopy, sociodemographic characteristics and lifestyle habits with probable food allergy.


RESULTS
Between September 2010 and September 2011, 480 cases and 4,950 controls completed the questionnaire. For all 9 allergens, factors associated with a higher risk of probable allergy were as follows: (1) personal history of eczema (in the first 2 years of life), asthma or hay fever (odds ratio, OR 2.3, 95% CI 1.6-3.5; OR 2.8, 95% CI 2.2-3.6, and OR 2.3, 95% CI 1.8-3.0, respectively), (2) maternal, paternal or sibling's food allergy (OR 3.7, 95% CI 2.5-5.6; OR 3.0, 95% CI 1.8-5.1, and OR 3.1, 95% CI 2.2-4.2), (3) high household income (top 20%; OR 1.5, 95% CI 1.2-2.0). Males and older individuals were less likely to have food allergy (OR 0.7, 95% CI 0.6-0.9, and OR 0.99, 95% CI 0.99-1.00). Eczema in the first 2 years of life was the strongest risk factor for egg, peanut, tree nut and fish allergy.


CONCLUSIONS
This is the largest population-based nested case-control study exploring factors associated with food allergies. Our results reveal that, in addition to previously reported factors, eczema in the first 2 years of life is consistently associated with food allergies.
Division of Pediatric Allergy and Clinical Immunology, Department of Pediatrics, McGill University Health Center, Montreal, Que., Canada.
Moshe
M
Ben-Shoshan
Lianne
L
Soller
Daniel W
DW
Harrington
Megan
M
Knoll
Sebastian
S
La Vieille
Joseph
J
Fragapane
Lawrence
L
Joseph
Yvan
Y
St Pierre
Kathie
K
Wilson
Susan J
SJ
Elliott
Ann E
AE
Clarke
D000293:Adolescent; D000328:Adult; D000485:Allergens / Q000276:immunology; D001249:Asthma / Q000276:immunology; D002170:Canada; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D004485:Eczema / Q000453:epidemiology* / Q000276:immunology; D005260:Female; D005512:Food Hypersensitivity / Q000453:epidemiology* / Q000276:immunology; D006801:Humans; D007223:Infant; D008019:Life Style; D008297:Male; D006255:Rhinitis, Allergic, Seasonal / Q000276:immunology; D066252:Sociological Factors; D011795:Surveys and Questionnaires
D000485:Allergens