Demographic Characteristics Associated with Food Allergy in a Nationwide Canadian Study Ann E
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Clarke et al. Allergy Asthma Clin Immunol (2021) 17:72 Allergy, Asthma & Clinical Immunology https://doi.org/10.1186/s13223-021-00572-z LETTER TO THE EDITOR Open Access Demographic characteristics associated with food allergy in a Nationwide Canadian Study Ann E. Clarke1* , Susan J. Elliott2, Yvan St. Pierre3, Lianne Soller4, Sebastien La Vieille5,6 and Moshe Ben‑Shoshan7 Abstract Introduction: We conducted a nationwide Canadian telephone survey on food allergy prevalence between February 2016 and January 2017, targeting vulnerable populations (New, Indigenous, and lower‑income Canadians). Objective: To examine the independent efect of demographic characteristics on food allergy. Methods: Canadian households with vulnerable populations were targeted using Canadian Census data and the household respondent reported whether each household member had a perceived (self‑reported) or probable (self‑ report of a convincing history or physician diagnosis) food allergy. The association between perceived and probable food allergy and demographic characteristics was assessed through weighted multivariable random efects logistic regressions. Results: Children, females, Canadian‑born participants, adults with post‑secondary education, and those residing in smaller households were more likely to report perceived or probable food allergy. Although immigrant parents self‑reported less food allergy, Canadian‑born children of Southeast/East Asian immigrant versus other immigrant or Canadian‑born parents reported more food allergy. Conclusion: We have demonstrated clear associations between demographic characteristics and food allergy, which may provide important clues to the environmental determinants of food allergy. Keywords: Food allergy, Race/ethnicity, Sociodemographic, Multivariate analysis, Epidemiology To the editor, Indigenous, and lower-income Canadians) using 2006 Canadian Census data (Additional fle 1). We compared Introduction prevalence between vulnerable and non-vulnerable We conducted a nationwide Canadian telephone survey populations [2] and showed (in univariable analysis) that on food allergy (FA) prevalence between February 2016 overall prevalence was lower in immigrants and adults and January 2017 (SPAACE [Surveying Prevalence of without post-secondary education. We now examine the Food Allergy in All Canadian Environments] to SPAACE independent efect of other demographic characteristics [S2S] [1]), targeting vulnerable populations (New, (age, sex, race/ethnicity, and household size), as well as immigrant status, education, and household income on presence of FA in multivariable analyses. *Correspondence: [email protected] 1 Division of Rheumatology, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada Full list of author information is available at the end of the article © The Author(s) 2021. 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The Creative Commons Public Domain Dedication waiver (http:// creat iveco mmons. org/ publi cdoma in/ zero/1. 0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data. Clarke et al. Allergy Asthma Clin Immunol (2021) 17:72 Page 2 of 7 Methods Chinese, Japanese, Korean), Black, Indigenous (self- Trough the use of 2006 Canadian Census data, the identifed with First Nations, Metis, or Inuit), Arab, census tracts (CT) from within the census metropolitan Latin American, West Asian (e.g., Afghan, Iranian, areas [3] that contained the highest proportion of Iraqi), white, or other. In the analysis, race/ethnicity was households with New, Indigenous, and lower-income stratifed as South Asian, Southeast/East Asian, Black, Canadian were selected and converted into postal codes Indigenous, white, or other (Arab, Latin American, West using the 2006 Statistics Canada postal code conversion Asian, other, multiple, and unknown race/ethnicity). fle. A random sample of household telephone numbers Te association between: (1) any perceived and (2) any with accompanying mailing addresses was then selected probable FA and multiple demographic characteristics from these postal codes by Info-Direct (a company was assessed through weighted univariable and maintaining household telephone directory listings in multivariable random efects logistic regressions, which Canada: Cornerstone Info-Direct, Toronto, Ontario, allowed for correlated observations within households. Canada) and ASDE Survey Sampler (Gatineau, Quebec, For both outcomes, the most informative multivariable Canada). model was specifed by selecting those demographic Due to the methodology for targeted sampling of the predictors for which an association remained statistically vulnerable populations, the smaller Canadian provinces signifcant at the 95% confdence level, after eliminating (Newfoundland and Labrador, Prince Edward Island, all others, starting with the least likely to be associated Nova Scotia, and New Brunswick) as well as the Canadian with the outcome (backward stepwise selection). territories (Northwest, Yukon, and Nunavut) were either Te Bonferroni method was also applied to assess excluded or not proportionately represented. Although the robustness of the associations. Te association our primary research objective was to ensure adequate between each individual perceived and probable FA and representation of the vulnerable populations, we also demographic characteristics was examined using the wanted to provide nationwide prevalence estimates. same multivariable model selection process as for any Hence, we sampled households from additional regions perceived and probable FA. In addition, the infuence of from the four smaller provinces that contained the parental birthplace on any perceived and probable FA highest proportion of the vulnerable populations in in Canadian-born children was assessed through the these provinces although the percentage was lower than same multivariable model selection process. In the frst in the larger provinces. In the territories, a sample of regression, which examined the association between any households was obtained from the entire region. perceived and probable FA and parental birthplace, the Te eligible adult household respondent (Additional sample was restricted to include only parents with at fle 1) completed the Food Allergy Prevalence least one Canadian-born child. In the second regression, Questionnaire (FAPQ) [1, 4, 5] in English or French, which examined the association between any perceived providing the following for each household member: and probable FA and parental birthplace, the sample allergy to peanut, tree nut, fsh, shellfsh, sesame, milk, included only Canadian-born children. In addition to egg, wheat, soy, or other foods, details on the most the predictors considered in the model for perceived and severe reaction for the nine allergens (symptoms, interval probable FA which involved the full sample, the following between exposure and symptoms, mode of contact, and predictors were also considered in the models with the if the allergy was physician-diagnosed), age, sex, race/ restricted samples: South Asian-born, Southeast/East ethnicity, birthplace, years in Canada (for non-Canadian- Asian-born, and non-Asian-born immigrant parent versus Canadian-born parent. born), education (if ≥ 18 years), and household income. Food allergy was defned as perceived or probable. An Te Research Ethics Boards of the Universities of individual was defned as having a perceived FA if they Calgary and Waterloo approved the study. were reported by the adult household respondent to have any FA; an individual was defned as having a probable FA Results (Additional fle 1) if the household respondent reported Of the 19,286 households targeted, 5874 of 11,592 symptoms/signs compatible with a convincing history eligible households completed the FAPQ, representing and/or physician diagnosis of a peanut, tree nut, fsh, a 50.7% household response rate. Of 15,322 individuals shellfsh, sesame, milk, egg, wheat, and/or soy allergy [1, participating, 14,818 provided sufcient information 2, 5]. to be included in this analysis. Our sample consisted Te FAPQ included the following race/ethnicity of 20.0% children, 48.4% of non-white race/ethnicity, options: South Asian (e.g. East Indian, Pakistani, Sri 33.4% immigrants, 51.9% of adults without post- Lankan), Southeast Asian (e.g. Cambodian, Filipino, secondary education, and 22.7% resided in lower-income Indonesian, Laotian, Vietnamese), East Asian (i.e., households (Table 1). Based on 2016 Canadian Census Clarke et al. Allergy Asthma Clin Immunol (2021) 17:72 Page 3 of 7 Table 1 Demographic characteristics among full sample and those without and with perceived and probabled food allergy Variable Full