Yvan St. Pierre

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.

Cancer risk in systemic lupus: An updated international multi-centre cohort study

OBJECTIVE To update estimates of cancer risk in SLE relative to the general population. METHODS A multisite international SLE cohort was linked with regional tumor registries. Standardized incidence ratios (SIRs) were calculated as the ratio of observed to expected cancers. RESULTS Across 30 centres, 16,409 patients were observed for 121,283 (average 7.4) person-years. In total, 644 cancers occurred. Some cancers, notably hematologic malignancies, were substantially increased (SIR 3.02, 95% confidence interval, CI, 2.48, 3.63), particularly non-Hodgkins lymphoma, NHL (SIR 4.39, 95% CI 3.46, 5.49) and leukemia. In addition, increased risks of cancer of the vulva (SIR 3.78, 95% CI 1.52, 7.78), lung (SIR 1.30, 95% CI 1.04, 1.60), thyroid (SIR 1.76, 95% CI 1.13, 2.61) and possibly liver (SIR 1.87, 95% CI 0.97, 3.27) were suggested. However, a decreased risk was estimated for breast (SIR 0.73, 95% CI 0.61-0.88), endometrial (SIR 0.44, 95% CI 0.23-0.77), and possibly ovarian cancers (0.64, 95% CI 0.34-1.10). The variability of comparative rates across different cancers meant that only a small increased risk was estimated across all cancers (SIR 1.14, 95% CI 1.05, 1.23). CONCLUSION These data estimate only a small increased risk in SLE (versus the general population) for cancer over-all. However, there is clearly an increased risk of NHL, and cancers of the vulva, lung, thyroid, and possibly liver. It remains unclear to what extent the association with NHL is mediated by innate versus exogenous factors. Similarly, the etiology of the decreased breast, endometrial, and possibly ovarian cancer risk is uncertain, though investigations are ongoing.

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)

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.

Role of food labels in accidental exposures in food-allergic individuals in Canada

BACKGROUND Little is known about the impact of food labeling on the allergic consumer. OBJECTIVE To determine the proportion of food-allergic individuals attributing an accidental exposure to inappropriate labeling, failure to read a food label, or ignoring a precautionary statement and to identify factors associated with accidental exposures. METHODS Food-allergic individuals or their caregivers were recruited from a Canadian registry of individuals with a physician-confirmed diagnosis of peanut allergy and from allergy awareness organizations. Participants completed questionnaires regarding accidental exposures due to specific food labeling issues. The association between accidental exposures and characteristics of food-allergic individuals or their caregivers was estimated using multivariate logistic regression models. RESULTS Of 1,862 potential participants, 1,454 (78.1%) responded. Of the 47.8% (95% confidence interval [CI], 45.1%-50.5%) of respondents who experienced an accidental exposure, 47.0% (95% CI, 43.1%-50.9%) attributed the event to inappropriate labeling, 28.6% (95% CI, 25.1%-32.2%) to failure to read a food label, and 8.3% (95% CI, 6.3%-10.7%) to ignoring a precautionary statement. Food-allergic individuals who were allergic to peanut, tree nut, fish, or shellfish were less likely to experience an accidental exposure due to the allergen not being identified in plain language. CONCLUSIONS A considerable proportion of accidental exposures are attributed to inappropriate labeling, failure to read labels, and ignoring precautionary statements. Clear and consistent labeling of food allergens combined with increased consumer education is necessary to improve consumer confidence and compliance and to reduce accidental exposures.

Lymphoma risk in systemic lupus: effects of disease activity versus treatment

Objective To examine disease activity versus treatment as lymphoma risk factors in systemic lupus erythematosus (SLE). Methods We performed case–cohort analyses within a multisite SLE cohort. Cancers were ascertained by regional registry linkages. Adjusted HRs for lymphoma were generated in regression models, for time-dependent exposures to immunomodulators (cyclophosphamide, azathioprine, methotrexate, mycophenolate, antimalarial drugs, glucocorticoids) demographics, calendar year, Sjogrens syndrome, SLE duration and disease activity. We used adjusted mean SLE Disease Activity Index scores (SLEDAI-2K) over time, and drugs were treated both categorically (ever/never) and as estimated cumulative doses. Results We studied 75 patients with lymphoma (72 non-Hodgkin, three Hodgkin) and 4961 cancer-free controls. Most lymphomas were of B-cell origin. As is seen in the general population, lymphoma risk in SLE was higher in male than female patients and increased with age. Lymphomas occurred a mean of 12.4 years (median 10.9) after SLE diagnosis. Unadjusted and adjusted analyses failed to show a clear association of disease activity with lymphoma risk. There was a suggestion of greater exposure to cyclophosphamide and to higher cumulative steroids in lymphoma cases than the cancer-free controls. Conclusions In this large SLE sample, there was a suggestion of higher lymphoma risk with exposure to cyclophosphamide and high cumulative steroids. Disease activity itself was not clearly associated with lymphoma risk. Further work will focus on genetic profiles that might interact with medication exposure to influence lymphoma risk in SLE.

THE USE OF ALTERNATIVE MEDICAL THERAPIES IN PATIENTS WITH SYSTEMIC LUPUS ERYTHEMATOSUS

OBJECTIVE As part of an ongoing study of health resource utilization and diminished productivity in patients with systemic lupus erythematosus (SLE), the use of alternative medical therapies was assessed. METHODS A cohort of 707 patients with SLE from 3 countries completed questionnaires on demographics, social support, health status (using the Short Form 36 health survey), satisfaction with health care, health resource utilization (conventional resources and alternative therapies), and time losses in labor market and non-labor market activities. Annual direct and indirect costs (1997 Canadian dollars) were calculated and compared for users and nonusers of alternative medical therapies. RESULTS Among the 707 patients, 352 (49.8%) were found to use alternative therapies and at similar rates across Canada, the United States, and the United Kingdom. Users were younger and better educated than nonusers, exhibited poorer levels of self-rated health status and satisfaction with medical care, and had minimal to no objective evidence of worse disease (according to the revised Systemic Lupus Activity Measure instrument). The mean of log direct medical costs for conventional resources was higher for users of select alternative therapies compared with nonusers. In a logistic regression, neither the number of alternative therapies used nor the individual therapy increased the probability of incurring indirect costs. CONCLUSION The use of alternative medical therapies is common in patients with SLE. Users of many alternative medical therapies accrue greater conventional medical costs compared with nonusers. The use of alternative medical therapy may be a marker for care-seeking behavior associated with higher consumption of conventional medical resources in the absence of demonstrable additional morbidity and should be considered in future cost analyses of patients with SLE.

Malignancies in Juvenile Idiopathic Arthritis: A Preliminary Report

Objective. To present preliminary data on incidence of malignancy in juvenile idiopathic arthritis (JIA), compared to general population rates. Methods. We examined cancer occurrence within JIA registries at 3 Canadian pediatric rheumatology centers. The subjects in the clinic registries were linked to regional tumor registries to determine the occurrence of invasive cancers over the observation period (spanning 1974–2006). The total number of cancers expected was determined by multiplying the person-years in the cohort by age, sex, and calendar year-specific cancer rates. The standardized incidence ratio (SIR, ratio of cancers observed to expected) was generated, with 95% confidence intervals. Results. The study sample consisted of 1834 patients. The female proportion was 67.6%; average age at entry to cohort was 8.6 years (SD 5.1). The majority were Caucasian. Subjects contributed 22,341 patient-years (average 12.2, SD 7.8). Within this observation period, one invasive cancer occurred, compared to 7.9 expected (SIR 0.12, 95% CI 0.0, 0.70). This was a hematological cancer (Hodgkin’s lymphoma), representing a SIR for hematological malignancies of 0.76 (95% CI 0.02, 4.21). Conclusion. Only one invasive cancer was identified in this large sample of individuals with JIA, observed for an average of 12.2 years each. These data suggest that, at least in the initial years following diagnosis of JIA, the risk of invasive cancers overall is not markedly increased. The results do not rule out the possibility of a baseline increased risk of hematological malignancies.

Availability of the epinephrine autoinjector at school in children with peanut allergy

BACKGROUND Peanut allergy accounts for most severe food-related allergic reactions, and accidental exposures are frequent. Delayed administration of epinephrine and the allergic individuals failure to personally carry epinephrine contribute to fatal outcomes. OBJECTIVES To describe epinephrine autoinjector availability at school and to determine factors that might affect autoinjector availability in children allergic to peanut. METHODS Two hundred seventy-one children with peanut allergy living in Quebec were queried about their autoinjector. Logistic regression models were used to select factors associated with device availability. RESULTS Four of 271 children diagnosed as having peanut allergy were not prescribed autoinjectors. Forty-eight percent of the children did not carry the autoinjector with them at school. In 78.0% of those, the autoinjector was located in the nurses or another school office, which was staffed by a full-time nurse only in 18.5%. Of all the respondents, those administered epinephrine for a previous reaction (odds ratio [OR], 2.7; 95% confidence interval [CI], 1.3-5.7), older children (OR, 1.1; 95% CI, 1.0-1.2), and those living only with their mother (OR, 3.4; 95% CI, 1.0-11.0) were more likely to carry the autoinjector with them at school. Of children 7 years or older, those who experienced a severe reaction were more likely to carry their autoinjector (OR, 3.3; 95% CI, 1.4-8.1). CONCLUSIONS Almost 50% of children allergic to peanut might experience a delay in anaphylaxis treatment due to limited access to their device. More education is required regarding the importance of a readily available autoinjector.

Estimating Indirect Costs in Primary Sjogren's Syndrome

Objective. To estimate the indirect costs associated with primary Sjögren’s syndrome (pSS) compared with rheumatoid arthritis (RA) and community controls. Methods. Data were obtained from 84 women patients with pSS as part of a study to develop a systemic activity measure, from 87 consecutive women patients with RA attending a hospital clinic, and from 96 women community controls on a general practice list. A modified economic component of the Stanford Health Assessment Questionnaire was used to assess lost productivity. Results. Using a conservative model, the estimated total annual indirect costs (95% CI) were £7677 (£5560, £9794) for pSS, £10,444 (£8206, £12,681) for RA, and £892 (£307, £1478) for controls. Using a model that maximizes the estimates, the equivalent figures were £13,502 (£9542, £17,463), £17,070 (£13,112, £21,028), and £3382 (£2187, £4578), respectively. These were all significantly greater at p < 0.001 for patient groups than for the control group. Conclusion. pSS is associated with significantly increased indirect costs equivalent to 69%–83% of that for patients with RA. This needs to be taken into account when evaluating the overall economic consequences of pSS.