Is the prevalence of peanut allergy increasing? A 5-year follow-up study in children in Montreal.

BACKGROUND: Studies suggest that peanut allergy prevalence might be increasing, but these results have not yet been substantiated. OBJECTIVE: We conducted a follow-up study to determine whether peanut allergy prevalence in Montreal is increasing. METHODS: Questionnaires regarding peanut ingestion were administered to parents of children in randomly selected kindergarten through grade 3 classrooms between December 2000 and September 2002 and between October 2005 and December 2007. Respondents were stratified as (1) peanut tolerant, (2) never/rarely ingest peanut, (3) convincing history of peanut allergy, or (4) uncertain history of peanut allergy. Children in group 3 with positive skin prick test responses were considered to have peanut allergy. Children in groups 2 and 4 with positive skin prick test responses had peanut-specific IgE levels measured, and if the value was less than 15 kU/L, an oral peanut challenge was performed. Multiple imputation was used to generate prevalence estimates that incorporated respondents providing incomplete data and nonrespondents. RESULTS: Of 8,039 children surveyed in 2005-2007, 64.2% of parents responded. Among those providing complete data, the prevalence was 1.63% (95% CI, 1.30% to 2.02%) in 2005-2007 versus 1.50% (95% CI, 1.16% to 1.92%) in 2000-2002. After adjustment for missing data, the prevalence was 1.62% (95% credible interval, 1.31% to 1.98%) versus 1.34% (95% credible interval, 1.08% to 1.64%), respectively. The differences between the prevalences in 2005-2007 and 2000-2002 were 0.13% (95% credible interval, -0.38% to 0.63%) among those providing complete data and 0.28% (95% credible interval, -0.15% to 0.70%) after adjustment for missing data. CONCLUSIONS: This is the first North American study to document temporal trends in peanut allergy prevalence by corroborating history with confirmatory tests. The results suggest a stable prevalence, but wide CIs preclude definitive conclusions.

Peanut-free guidelines reduce school lunch peanut contents.

BACKGROUND: Some schools implement peanut-free guidelines (PFG) requesting omission of peanut from lunches. Our study assessed parental awareness of, and adherence to, PFG by comparing the percentage of lunches containing peanut between primary school classes with and without PFG in Montreal, Québec. METHODS: Parents, school principals and teachers were queried concerning the school's PFG and children's lunches were inspected by a dietician for peanut-containing foods. RESULTS: When lunch peanut contents were compared in randomly selected classrooms, peanut was found in 5/861 lunches in classes with PFG (0.6%, 95% CI 0.2% to 1.4%) and in 84/845 lunches in classes without PFG (9.9%, 95% CI 8.0% to 12.2%), a 9.4% (95% CI 7.3% to 11.4%) difference. CONCLUSIONS: Our findings demonstrate that PFG are effective in reducing peanut in classrooms providing a basis for future research that should address whether or not the reduction in peanut achieved by restrictive lunch policies decreases the morbidity associated with peanut allergy in the school setting.

Prevalence of peanut allergy in primary-school children in Montreal, Canada.

BACKGROUND: Peanut allergy is receiving increasing attention. Only one study has estimated the prevalence in North America, but it did not corroborate history with diagnostic testing. OBJECTIVE: We estimated the prevalence of peanut allergy in Montreal by administering questionnaires regarding peanut ingestion to children in kindergarten through grade 3 in randomly selected schools. METHODS: Respondents were stratified as follows: (1). peanut tolerant, (2). never-rarely ingest peanut, (3). convincing history of peanut allergy, and (4). uncertain history of peanut allergy. Groups 2, 3, and 4 underwent peanut skin prick tests (SPTs), and if the responses were positive in groups 2 or 4, measurement of peanut-specific IgE were undertaken. Children in group 3 with a positive SPT response were considered allergic to peanut without further testing. Children in groups 2 and 4 with peanut-specific IgE levels of less than 15 kU/L underwent oral peanut challenges. RESULTS: Of the 7768 children surveyed, 4339 responded, 94.6% in group 1. The prevalence of peanut allergy was 1.50% (95% CI, 1.16%-1.92%). When multiple imputation was used to incorporate data on those responding to the questionnaire but withdrawing before testing, the estimated prevalence increased to 1.76% (95% CI, 1.38%-2.21%). When data regarding the peanut allergy status of nonresponders (as declared to the school before the study) were also incorporated, the estimated prevalence was 1.34% (95% CI, 1.08%-1.64%). CONCLUSION: Our prevalence study is the first in North America to corroborate history with confirmatory testing and the largest worldwide to incorporate these techniques. We have shown that, even with conservative assumptions, prevalence exceeds 1.0%.

Peanut allergy: an overview.

Peanut allergy accounts for the majority of severe food-related allergic reactions. It tends to present early in life, and affected individuals generally do not outgrow it. In highly sensitized people, trace quantities can induce an allergic reaction. In this review, we will discuss the prevalence, clinical characteristics, diagnosis, natural history and management of peanut allergy.