Daniel W. Harrington

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)

Weighing the importance of neighbourhood: A multilevel exploration of the determinants of overweight and obesity

Overweight and obesity have reached epidemic proportions in many countries, including Canada. In addition to becoming critical public health challenges in and of themselves, they represent major risk factors for chronic disease and disability (e.g. cardiovascular disease, diabetes). The various symptoms and co-morbidities associated with these chronic conditions place tremendous stress on the Canadian health care system, generating economic concern. This research takes a population health approach to the study of obesity, examining the complex relationships between individual demographics and behaviours, and aspects of the local social and physical environments. A subset of a nationally representative survey was linked to neighbourhood-level data from the 1991 Canadian Census, and analysed from a multilevel perspective. This study found substantial area-level variation in body mass index and waist circumference, and discovered an important role for neighbourhood-level characteristics independent of individual-level characteristics. These findings provide evidence that the underlying mechanisms driving the increasing prevalence of overweight and obesity may be so called obesogenic environments that encourage physical inactivity and unhealthy eating. An effective policy response must address environmental conditions in order to curb current obesity trends.

Protective Behavior and West Nile Virus Risk

We conducted a cross-sectional, household survey in Oakville, Ontario, where an outbreak of West Nile virus (WNV) in 2002 led to an unprecedented number of cases of meningitis and encephalitis. Practicing >2 personal protective behavior traits reduced the risk for WNV infection by half.

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.

Realizing neighbourhood potential? The role of the availability of health care services on contact with a primary care physician.

Access to health services research has traditionally focused on demographic, socioeconomic, and need-based factors, resulting in a relative lack of knowledge regarding place-based determinants. Further, much of what we know comes from international, national, and regional study. This study analyzes survey data (n=1635) to explore the relationship between neighbourhood-level potential access (i.e., availability) and realized access (i.e., use) in two Canadian cities. Controlling for predisposing, enabling and need factors, living in a well-served neighbourhood was a significant predictor of realized access, particularly in Saskatoon. This suggests that the relationship between potential and realized access may be modified by place-based factors.

Frames, claims and audiences: construction of food allergies in the Canadian media

Food allergies are newly emerging health risks, and some evidence indicates that their prevalence is increasing. Public perception, however, is that the prevalence of food allergies is much greater than systematic estimates suggest. As food allergies increasingly permeate everyday life, this paper explores how associated risks are constructed through the mass media. In particular, nine years of media coverage of food allergies are analysed through the lens of issue framing and claims-making. Results show that advocates and affected individuals dominate discussions around policy action, while researchers and health professionals are diagnosing the causes of food allergy. Results also suggest that there is competition over the definition of food allergies, which may, in turn, be shaping public understanding of the related risks. There is also an indication that the framing of food allergies is evolving over time, and that the discussion is becoming increasingly one-sided with affected individuals leading the charge.

Exploring the Determinants of the Perceived Risk of Food Allergies in Canada

ABSTRACT Food allergies are emerging health risks in much of the Western world, and some evidence suggests prevalence is increasing. Despite lacking scientific consensus around prevalence and management, policies and regulations are being implemented in public spaces (e.g., schools). These policies have been criticized as extreme in the literature, in the media, and by the non-allergic population. Backlash appears to be resulting from different perceptions of risk between different groups. This article uses a recently assembled national dataset (n = 3,666) to explore how Canadians perceive the risks of food allergy. Analyses revealed that almost 20% self-report having an allergic person in the household, while the average respondent estimated the prevalence of food allergies in Canada to be 30%. Both of these measures overestimate the true clinically defined prevalence (7.5%), indicating an inflated public understanding of the risks of food allergies. Seventy percent reported food allergies to be substantial risks to the Canadian population. Multivariate logistic regression models revealed important determinants of risk perception including demographic, experience-based, attitudinal, and regional predictors. Results are discussed in terms of understanding emerging health risks in the post-industrial era, and implications for both policy and risk communication.

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.