Sebastien La Vieille

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)

Clinical features and symptom recovery on a gluten-free diet in Canadian adults with celiac disease.

BACKGROUND Celiac disease can present with mild or nongastrointestinal symptoms, and may escape timely recognition. The treatment of celiac disease involves a gluten-free diet, which is complex and challenging. OBJECTIVE To evaluate clinical features and symptom recovery on a gluten-free diet in a Canadian adult celiac population. METHODS All adult members (n=10,693) of the two national celiac support organizations, the Canadian Celiac Association and Fondation québécoise de la maladie coeliaque, were surveyed using a questionnaire. RESULTS A total of 5912 individuals (≥18 years of age) with biopsy-confirmed celiac disease and⁄or dermatitis herpetiformis completed the survey. The female to male ratio was 3:1, and mean (± SD) age at diagnosis was 45.2 ± 16.4 years. Mean time to diagnosis after onset of symptoms was 12.0 ± 14.4 years. Abdominal pain and bloating (84.9%), extreme weakness⁄tiredness (74.2%), diarrhea (71.7%) and anemia (67.8%) were the most commonly reported symptoms at the time of diagnosis. Many respondents continued to experience symptoms after being on a gluten-free diet for >5 years. Sex differences were reported in clinical features before diagnosis, recovery after being on gluten-free diet and perceived quality of life, with women experiencing more difficulties than men. CONCLUSIONS Delays in diagnosis of celiac disease in Canada remain unacceptably long despite wider availability of serological screening tests. Many patients report continuing symptoms despite adhering to a gluten-free diet for >5 years, with women experiencing more symptoms and a lower recovery rate than men. Awareness of celiac disease needs improvement, and follow-up with a physician and a dietitian is essential for all patients with celiac disease.

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

Tryptase levels in children presenting with anaphylaxis: Temporal trends and associated factors

BACKGROUND The diagnosis of anaphylaxis currently relies on suggestive clinical history after exposure to a potential triggering factor because no reliable diagnostic marker is available to confirm the diagnosis. OBJECTIVES We aimed to evaluate tryptase levels in children with anaphylaxis and to examine predictors of elevated tryptase level (defined as ≥11.4 μg/L during reaction and for those with a baseline level, defined as a reaction level of at least 2 ng/mL + 1.2 × [postreaction tryptase level]). METHODS Children presenting with anaphylaxis to the Montreal Childrens Hospital were recruited over a 4-year period. Symptoms, triggers, and management of anaphylaxis were documented. Levels during the reaction and approximately 9 months after the reaction were compared on the basis of paired means using the t distribution. Multivariate linear and logistic regressions were used to evaluate the association between tryptase levels and risk factors. RESULTS Over a 4-year period, 203 children had serum tryptase levels measured. Among these, 39 children (19.2%; 95% CI, 14.1%-25.4%) had elevated levels. Only severe reactions were associated with reaction levels of 11.4 μg/L or more (odds ratio, 6.5; 95% CI, 2.2-19.0). Milk-induced anaphylaxis and severe reactions were more likely associated with increased tryptase levels (beta-adjusted, 4.0; 95% CI, 0.95-7.0, and 7.5; 95% CI, 4.8-10.3, respectively). Reaction levels exceeding the threshold level of 2 ng/mL + 1.2 × (postreaction tryptase level) detected most of the anaphylactic reactions, particularly if baseline levels were taken within 2 months of the reaction. CONCLUSIONS Tryptase levels are particularly useful for the diagnosis of severe and/or milk-induced anaphylaxis. Assessing the difference between reaction and postreaction tryptase levels may improve diagnostic sensitivity.

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.

Celiac Disease and Gluten-Free Oats: A Canadian Position Based on a Literature Review

This paper provides an overview of the latest scientific data related to the safety of uncontaminated oats (<20 ppm of gluten) in the diet of individuals with celiac disease (CD). It updates the previous Health Canada position posted on the Health Canada website in 2007 and a related paper published in 2009. It considers a number of recent studies published between January 2008 and January 2015. While recognizing that a few people with celiac disease seem to be clinically intolerant to oats, this review concludes that oats uncontaminated by gluten-containing cereals (wheat, rye, and barley) can be safely ingested by most patients with celiac disease and that there is no conclusive evidence that the consumption of uncontaminated or specially produced oats containing no greater than 20 ppm gluten by patients with celiac disease should be limited to a specific daily amount. However, individuals with CD should observe a stabilization phase before introducing uncontaminated oats to the gluten-free diet (GFD). Oats uncontaminated with gluten should only be introduced after all symptoms of celiac disease have resolved and the individual has been on a GFD for a minimum of 6 months. Long-term regular medical follow-up of these patients is recommended but this is no different recommendation to celiac individuals on a GFD without oats.

The Risk of Recurrent Anaphylaxis

Objectives To determine the recurrence rate of anaphylaxis in children medically attended in an emergency department (ED), we performed a prospective cohort study to evaluate prehospital and ED management of children with recurrent anaphylaxis and to assess factors associated with recurrent anaphylaxis. Study design As part of the Cross‐Canada Anaphylaxis Registry, parents of children with anaphylaxis identified prospectively in 3 EDs and through an emergency medical response service were contacted annually after presentation and queried on subsequent reactions. Cox regression analysis determined factors associated with recurrence. Results Among 292 children who were registered as having had medical attended anaphylaxis, 68.5% completed annual follow‐up questionnaires. Forty‐seven patients experienced 65 episodes of anaphylaxis during 369 patient‐years of follow‐up. Food was the trigger in 84.6% of cases, and epinephrine was used in 66.2%. In 50.8%, epinephrine was used outside the health care facility, and 81.7% were brought to a health care facility for treatment. Asthma, reaction triggered by food, and use of epinephrine during the index episode increased the odds of recurrent reaction. Patients whose initial reaction was triggered by peanut were less likely to have a recurrent reaction. Conclusions We report a yearly anaphylaxis recurrence rate of 17.6% in children. There is substantial underuse of epinephrine in cases of anaphylaxis. Educational programs that promote effective avoidance strategies and prompt use of epinephrine are required.

Anaphylaxis across two Canadian pediatric centers: evaluating management disparities

Background There are no data on the percentage of visits due to anaphylaxis in the emergency department (ED), triggers, and management of anaphylaxis across different provinces in Canada. Objective To compare the percentage of anaphylaxis cases among all ED visits, as well as the triggers and management of anaphylaxis between two Canadian pediatric EDs (PEDs). Methods As part of the Cross-Canada Anaphylaxis Registry (C-CARE), children presenting to the British Columbia Children’s Hospital (BCCH) and Montreal Children’s Hospital (MCH) EDs with anaphylaxis were recruited. Characteristics, triggers, and management of anaphylaxis were documented using a standardized data entry form. Differences in demographics, triggers, and management were determined by comparing the difference of proportions and 95% confidence interval. Results Between June 2014 and June 2016, there were 346 visits due to anaphylaxis among 93,730 PED visits at the BCCH ED and 631 anaphylaxis visits among 164,669 pediatric visits at the MCH ED. In both centers, the majority of cases were triggered by food (BCCH 91.3% [88.7, 94.0], MCH 82.4% [79.7, 85.3]), of which peanuts were the most common culprit (24.7% [20.9, 29.9] and 19.0% [15.8, 22.7], respectively). Pre-hospital administration of epinephrine (BCCH 27.7% [23.2, 32.8], MCH 33.1% [29.5, 37.0]) and antihistamines (BCCH 50.6% [45.2, 56.0], MCH 47.1% [43.1, 51.0]) was similar. In-hospital management differed in terms of increased epinephrine, antihistamine, and steroid use at the BCCH (59.2% [53.9, 64.4], 59.8% [54.4, 65.0], and 60.1% [54.7, 65.3], respectively) compared to the MCH (42.2% [38.3, 46.2], 36.2% [32.5, 40.1], and 11.9% [9.5, 14.8], respectively). Despite differences in management, percentage of cases admitted to the intensive care unit was similar between the two centers. Conclusion Compared to previous European and North American reports, there is a high percentage of anaphylaxis cases in two PEDs across Canada with substantial differences in hospital management practices. It is crucial to develop training programs that aim to increase epinephrine use in anaphylaxis.

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

Possession of epinephrine auto-injectors by Canadians with food allergies

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.