Lianne Soller

A population-based study on peanut, tree nut, fish, shellfish, and sesame allergy prevalence in Canada

BACKGROUND Recent studies suggest an increased prevalence of food-induced allergy and an increased incidence of food-related anaphylaxis. However, prevalence estimates of food allergies vary considerably between studies. OBJECTIVES To determine the prevalence of peanut, tree nut, fish, shellfish, and sesame allergy in Canada. METHODS Using comparable methodology to Sicherer et al in the United States in 2002, we performed a cross-Canada, random telephone survey. Food allergy was defined as perceived (based on self-report), probable (based on convincing history or self-report of physician diagnosis), or confirmed (based on history and evidence of confirmatory tests). RESULTS Of 10,596 households surveyed in 2008 and 2009, 3666 responded (34.6% participation rate), of which 3613 completed the entire interview, representing 9667 individuals. The prevalence of perceived peanut allergy was 1.00% (95% CI, 0.80%-1.20%); tree nut, 1.22% (95% CI, 1.00%-1.44%); fish, 0.51% (95% CI, 0.37%-0.65%); shellfish, 1.60% (95% CI, 1.35%-1.86%); and sesame, 0.10% (95% CI, 0.04%-0.17%). The prevalence of probable allergy was 0.93% (95% CI, 0.74%-1.12%); 1.14% (95% CI, 0.92%-1.35%); 0.48% (95% CI, 0.34%-0.61%); 1.42% (95% CI, 1.18%-1.66%); and 0.09% (95% CI, 0.03%-0.15%), respectively. Because of the infrequency of confirmatory tests and the difficulty in obtaining results if performed, the prevalence of confirmed allergy was much lower. CONCLUSION This is the first nationwide Canadian study to determine the prevalence of severe food allergies. Our results indicate disparities between perceived and confirmed food allergy that might contribute to the wide range of published prevalence estimates.

Overall prevalence of self-reported food allergy in Canada

Estimate 1: Including all adults Peanut 1.77 (1.21-2.33) 0.78 (0.58-0.97) 1.00 (0.80-1.20) Tree nut 1.73 (1.16-2.30) 1.07 (0.84-1.30) 1.22 (1.00-1.44) Fish 0.18 (0.00-0.36) 0.60 (0.43-0.78) 0.51 (0.37-0.65) Shellfish 0.55 (0.21-0.88) 1.91 (1.60-2.23) 1.60 (1.35-1.86) Sesame 0.23 (0.03-0.43) 0.07 (0.01-0.13) 0.10 (0.04-0.17) Milk 2.23 (1.51-2.95) 1.89 (1.56-2.21) 1.97 (1.64-2.29) Egg 1.23 (0.69-1.77) 0.67 (0.48-0.86) 0.80 (0.61-0.99) Wheat 0.45 (0.08-0.83) 0.86 (0.63-1.08) 0.77 (0.57-0.96) Soy 0.32 (0.08-0.55) 0.16 (0.07-0.25) 0.20 (0.10-0.30) Fruits 1.14 (0.68-1.60) 1.61 (1.32-1.89) 1.50 (1.25-1.75) Vegetables 0.45 (0.17-0.74) 1.29 (1.02-1.55) 1.10 (0.88-1.31) Other 1.32 (0.80-1.84) 1.67 (1.37-1.97) 1.59 (1.32-1.86) All foods 7.14 (5.92-8.36) 8.34 (7.69-8.99) 8.07 (7.47-8.67) Estimate 2: Excluding some adults All foods 7.14 (5.92-8.36) 6.56 (5.99-7.13) 6.69 (6.15-7.24) Estimate 3: Estimate 2 adjusted for nonresponse All foods 7.12 (6.07-8.28) 6.58 (6.22-6.96) 6.67 (6.19-7.17)

Adjusting for nonresponse bias corrects overestimates of food allergy prevalence

Perceived Peanut 2.4 (1.6, 3.2) 0.7 (0.5, 0.9) 1.1 (0.9, 1.3) Tree nut 1.6 (1.0, 2.3) 1.2 (0.9, 1.5) 1.3 (1.0, 1.6) Fish 1.0 (0.3, 1.8) 0.6 (0.4, 0.8) 0.7 (0.5, 0.9) Shellfish 1.4 (0.6, 2.1) 1.9 (1.5, 2.2) 1.7 (1.4, 2.0) Sesame 0.1 (0.0, 0.3) 0.2 (0.1, 0.3) 0.2 (0.1, 0.3) Milk 0.7 (0.3, 1.1) 0.7 (0.5, 0.9) 0.7 (0.5, 0.9) Adjusting for nonresponse bias corrects overestimates of food allergy prevalence Lianne Soller, BSc, MSc, PhD candidate, Moshe Ben-Shoshan, MD, MSc, Daniel W. Harrington, MA, PhD, Megan Knoll, MSc, Joseph Fragapane, BEng, MD, Lawrence Joseph, PhD, Yvan St. Pierre, MSc, Sebastien La Vieille, MD, Kathi Wilson, PhD, Susan J. Elliott, PhD, and Ann E. Clarke, MD, MSc

Demographic predictors of peanut, tree nut, fish, shellfish, and sesame allergy in Canada.

Background. Studies suggest that the rising prevalence of food allergy during recent decades may have stabilized. Although genetics undoubtedly contribute to the emergence of food allergy, it is likely that other factors play a crucial role in mediating such short-term changes. Objective. To identify potential demographic predictors of food allergies. Methods. We performed a cross-Canada, random telephone survey. Criteria for food allergy were self-report of convincing symptoms and/or physician diagnosis of allergy. Multivariate logistic regressions were used to assess potential determinants. Results. Of 10,596 households surveyed in 2008/2009, 3666 responded, representing 9667 individuals. Peanut, tree nut, and sesame allergy were more common in children (odds ratio (OR) 2.24 (95% CI, 1.40, 3.59), 1.73 (95% CI, 1.11, 2.68), and 5.63 (95% CI, 1.39, 22.87), resp.) while fish and shellfish allergy were less common in children (OR 0.17 (95% CI, 0.04, 0.72) and 0.29 (95% CI, 0.14, 0.61)). Tree nut and shellfish allergy were less common in males (OR 0.55 (95% CI, 0.36, 0.83) and 0.63 (95% CI, 0.43, 0.91)). Shellfish allergy was more common in urban settings (OR 1.55 (95% CI, 1.04, 2.31)). There was a trend for most food allergies to be more prevalent in the more educated (tree nut OR 1.90 (95% CI, 1.18, 3.04)) and less prevalent in immigrants (shellfish OR 0.49 (95% CI, 0.26, 0.95)), but wide CIs preclude definitive conclusions for most foods. Conclusions. Our results reveal that in addition to age and sex, place of residence, socioeconomic status, and birth place may influence the development of food allergy.

Prevalence and Predictors of Food Allergy in Canada: A Focus on Vulnerable Populations

BACKGROUND Studies suggest that individuals of low education and/or income, new Canadians (immigrated <10 years ago), and individuals of Aboriginal identity may have fewer food allergies than the general population. However, given the difficulty in recruiting such populations (hereafter referred to as vulnerable populations), by using conventional survey methodologies, the prevalence of food allergy among these populations in Canada has not been estimated. OBJECTIVES To estimate the prevalence of food allergy among vulnerable populations in Canada, to compare with the nonvulnerable populations and to identify demographic characteristics predictive of food allergy. METHODS By using 2006 Canadian Census data, postal codes with high proportions of vulnerable populations were identified and households were randomly selected to participate in a telephone survey. Information on food allergies and demographics was collected. Prevalence estimates were weighted by using Census data to account for the targeted sampling. Multivariable logistic regression was used to identify predictors of food allergy. RESULTS Of 12,762 eligible households contacted, 5734 households completed the questionnaire (45% response rate). Food allergy was less common among adults without postsecondary education versus those with postsecondary education (6.4% [95% CI, 5.5%-7.3%] vs 8.9% [95% CI, 7.7%-10%]) and new Canadians versus those born in Canada (3.2% [95% CI, 2.2%-4.3%] vs 8.2% [95% CI, 7.4%-9.1%]). There was no difference in prevalence between those of low and of high income or those with and without Aboriginal identity. CONCLUSION Analysis of our data suggests that individuals of low education and new Canadians self-report fewer allergies, which may be due to genetics, environment, lack of appropriate health care, or lack of awareness of allergies, which reduces self-report.

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 siblings 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.

The use of incentives in vulnerable populations for a telephone survey: a randomized controlled trial

BackgroundPoor response rates in prevalence surveys can lead to nonresponse bias thereby compromising the validity of prevalence estimates. We conducted a telephone survey of randomly selected households to estimate the prevalence of food allergy in the 10 Canadian provinces between May 2008 and March 2009 (the SCAAALAR study: Surveying Canadians to Assess the Prevalence of Common Food Allergies and Attitudes towards Food LAbeling and Risk). A household response rate of only 34.6% was attained, and those of lower socioeconomic status, lower education and new Canadians were underrepresented. We are now attempting to target these vulnerable populations in the SPAACE study (Surveying the Prevalence of Food Allergy in All Canadian Environments) and are evaluating strategies to increase the response rate. Although the success of incentives to increase response rates has been demonstrated previously, no studies have specifically examined the use of unconditional incentives in these vulnerable populations in a telephone survey. The pilot study will compare response rates between vulnerable Canadian populations receiving and not receiving an incentive.FindingsRandomly selected households were randomly assigned to receive either a

Management of anaphylaxis in schools: Evaluation of an epinephrine auto-injector (EpiPen®) use by school personnel and comparison of two approaches of soliciting participation

5 incentive or no incentive. The between group differences in response rates and 95% confidence intervals (CIs) were calculated. The response rates for the incentive and non-incentive groups were 36.1% and 28.7% respectively, yielding a between group difference of 7.4% (−0.7%, 15.6%).ConclusionAlthough the wide CI precludes definitive conclusions, our results suggest that unconditional incentives are effective in vulnerable populations for telephone surveys.

Possession of epinephrine auto-injectors by Canadians with food allergies

BackgroundThere has been no large study characterizing selection bias in allergy and evaluating school personnel’s ability to use an epinephrine auto-injector (EpiPen®). Our objective was to determine if the consent process introduces selection bias by comparing 2 methods of soliciting participation of school personnel in a study evaluating their ability to demonstrate the EpiPen®.MethodsSchool personnel from randomly selected schools in Quebec were approached using a 1) partial or 2) full disclosure approach and were assessed on their ability to use the EpiPen® and identify anaphylaxis.Results343 school personnel participated. In the full disclosure group, the participation rate was lower: 21.9% (95%CI, 19.0%-25.2%) versus 40.7% (95%CI, 36.1%-45.3%), but more participants achieved a perfect score: 26.3% (95%CI, 19.6%-33.9%) versus 15.8% (95%CI, 10.8%-21.8%), and identified 3 signs of anaphylaxis: 71.8% (95%CI, 64.0%-78.7%) versus 55.6% (95%CI, 48.2%-62.9%).ConclusionsSelection bias is suspected as school personnel who were fully informed of the purpose of the assessment were less likely to participate; those who participated among the fully informed were more likely to earn perfect scores and identify anaphylaxis. As the process of consent can influence participation and bias outcomes, researchers and Ethics Boards need to consider conditions under which studies can proceed without full consent. Despite training, school personnel perform poorly when asked to demonstrate the EpiPen®.

Canadians' perception of food allergy risk

To the Editor: Although there is unanimous agreement that epinephrine is the first-line treatment for anaphylaxis, many with food allergy have not been prescribed an epinephrine auto-injector (EAI). As part of our nationwide Canadian study on the prevalence of food allergy, households from the 10 Canadian provinces were randomly selected from the electronic white pages and were telephoned between May 2008 and March 2009. Households self-reporting an allergy to peanut, tree nut, fish, shellfish, and/ or sesame were recontacted within 4 months of the telephone survey and asked whether the individual(s) with allergy currently had an EAI. There was no differentiation between EAI formulations currently available in Canada (EpiPen; King Pharmaceuticals Canada, Mississauga, Ontario, Canada, and Twinject; Paladin Labs Inc, St-Laurent, Quebec, Canada). Two categories of respondents with allergy were defined: (1) those reporting a convincing history of an IgE-mediated allergic reaction* and/or a physician diagnosis of an allergy to peanut, tree nut, fish, shellfish, or sesame, termed the probable group, and (2) those reporting a physician diagnosis of an allergy to peanut, tree nut, fish, shellfish, or sesame, termed the diagnosed group. Multivariate logistic regression models were performed for each group of respondents to identify factors associated with having an EAI; multiple imputation techniques were used to adjust for missing data for the low-income variable. Both models were hierarchical using the following household-level variables: postsecondary education of household respondent (attained college/university degree), low-income household, marital status of household respondent (married/living with partner), urban location of household, and birthplace of household respondent (not born in Canada). The following individual-level data of the allergic participants were also included: age (<18 years), sex, type of allergy (peanut, tree nut, or sesame), multiple allergies (allergy to >1 of peanut, tree nut, sesame, fish, or shellfish), age at most severe reaction, treatment with epinephrine during most severe reaction, multiple allergic reactions, and self-report of diagnostic allergy testing. Of 10,596 households contacted, 3,666 responded (35% participation rate), of which 3,613 completed the entire interview, representing 9,667 individuals. Of these 9,667 individuals, 310 (3.2%) were considered to have a probable food allergy to at least one of the following: peanut, tree nut, fish shellfish, and/or sesame. Of those with probable food allergies, 261 (84%) could be recontacted and queried on the EAI (convincing history only, n5 63; diagnosis only, n5 38; convincing history and diagnosis,