Prevalence and association of asthma and allergic sensitization with dietary factors in schoolchildren: data from the french six cities study.

BACKGROUND: The prevalence of asthma and allergy has recently risen among children. This increase in prevalence might be related to various factors, particularly diet. The aim of this study is to assess the prevalence and association of asthma and allergic sensitization with dietary factors in the French Six Cities Study. METHODS: Cross-sectional studies were performed among 7432 schoolchildren aged 9-11 years in Bordeaux, Clermont-Ferrand, Créteil, Marseille, Reims, and Strasbourg. Parental questionnaires, based on the International Study on Asthma and Allergies in Childhood (ISAAC), were used to collect information on allergic diseases and potential exposure factors including a food frequency questionnaire to evaluate dietary habits. Skin prick testing to common allergens for allergic sensitization and bronchial hyper-responsiveness (BHR) testing to exercise were performed. Confounders control was performed with multiple logistic regressions. RESULTS: Asthma symptoms, asthma and allergic sensitization were more prevalent in boys than in girls and were more prevalent in the South than in the North of France. After adjustment for confounders, fruit juice intake was associated with a low prevalence of lifetime asthma (ORa [95 % CI]; 0.73 [0.56-0.97]), butter intake was positively associated with atopic wheeze (1.48 [1.07-2.05]) and having lunch at the canteen 1-2 times/week compared to never or occasionally was associated with a lower prevalence of past year wheeze (0.71 [0.52-0.96]), lifetime asthma (0.76 [0.60-0.96]) and allergic sensitization (0.80 [0.67-0.95]). Meat intake was inversely related to past year wheeze among atopic children (0.68 [0.50-0.98]) while fast food consumption and butter intake were associated with an increase prevalence of asthma (2.39 [1.47-3.93] and 1.51 [1.17-2.00] respectively). Fish intake was associated with a lower prevalence of asthma among non-atopic children (0.61 [0.43-0.87]. None of the dietary factors was associated with BHR. CONCLUSIONS: Diet is associated with wheeze, asthma and allergic sensitization but not with BHR in children. These results provide further evidence that adherence to a healthy diet including fruits, meat and fish seems to have a protective effect on asthma and allergy in childhood. However, prospective and experimental studies are needed to provide causal evidence concerning the effect of diet on asthma and atopy.

Poor air quality in classrooms related to asthma and rhinitis in primary schoolchildren of the French 6 Cities Study.

BACKGROUND: Relationships between indoor air quality (IAQ) found in schools and the allergic and respiratory health of schoolchildren have been insufficiently explored. A survey was conducted in a large sample of classrooms of primary schools in France to provide objective assessments of IAQ to which young schoolchildren are exposed in classrooms, and to relate exposure to major air pollutants found in classrooms to asthma and allergies of schoolchildren. METHODS: Concentrations of fine particles with aerodynamic diameter ≤2.5 µm (PM(2.5)), nitrogen dioxide (NO(2)) and three aldehydes were objectively assessed in 401 randomly chosen classrooms in 108 primary schools attended by 6590 children (mean age 10.4 years, SD ±0.7) in the French 6 Cities Study. The survey incorporated a medical visit including skin prick testing (SPT) for common allergens, a test for screening exercise-induced asthma (EIA) and a standardised health questionnaire completed by parents. RESULTS: Children were differently exposed to poor air quality in classrooms, with almost 30% being highly exposed according to available standards. After adjusting for confounders, past year rhinoconjunctivitis was significantly associated with high levels of formaldehyde in classrooms (OR 1.19; 95% CI 1.04 to 1.36). Additionally, an increased prevalence of past year asthma was found in the classrooms with high levels of PM(2.5) (OR 1.21; 95% CI 1.05 to 1.39), acrolein (OR 1.22; 95% CI 1.09 to 1.38) and NO(2) (OR 1.16; 95% CI 0.95 to 1.41) compared with others. The relationship was observed mostly for allergic asthma as defined using SPT. A significant positive correlation was found between EIA and the levels of PM(2.5) and acrolein in the same week. CONCLUSIONS: In this random sample, air quality in classrooms was poor, varied significantly among schools and cities, and was related to an increased prevalence of clinical manifestations of asthma and rhinitis in schoolchildren. Children with a background of allergies seemed at increased risk.

[Long-term exposure to urban air pollution measured through a dispersion model and the risk of asthma and allergy in children]. / Exposition a long terme a la pollution urbaine evaluée par un modèle de dispersion et risque d'asthme et d'allergie chez l'enfant.

The impact of chronic urban air pollution on asthma and allergy remains controversial, probably because exposure is difficult to evaluate. In this cross-sectional epidemiological survey of 9- to 11-year-old children living in six French towns, levels of air pollution were estimated by using dispersion models that take into account background air pollution levels along with traffic density, topography and meteorological conditions. We estimated three-year exposure, in the school environment, to benzene, volatile organic compounds, SO2, particles less than 10 microns in diameter (PM10), nitrous oxides (NO2 and NOx) and CO, which are the main urban air pollutants. Several health indicators were gathered by means of a questionnaire, a physical examination, skin prick testing, and measurement of peak-flow variations following an exercise test. Among the nearly 5000 children who had been living in the survey area for at least three years, the 12-month and cumulative prevalence rates of asthma and exercise-induced hyper-reactivity correlated with estimated levels of benzene, SO2, PM10, NOx and CO. The 12-month and cumulative prevalence rates of atopic dermatitis correlated with estimated benzene, PM10, NO2, NOx and CO levels. Pollen sensitization correlated with benzene and PM10 levels, and the cumulative prevalence of allergic rhinitis correlated with the PM10 level. These associations remained statistically significant among children who had spent their entire lives in the same community.

High body mass index and allergies in schoolchildren: the French six cities study.

BACKGROUND: The prevalence of allergic diseases such as asthma, allergic rhinitis and atopic dermatitis is increasing rapidly worldwide, especially among children and in western countries. This coincides with an increase in body mass index (BMI), which might be a major risk factor for atopic diseases. OBJECTIVES: To study the relationship between high BMI and allergic diseases, as well as skin-prick test (SPT) positivity and exercise-induced asthma (EIA) in 6733 randomly selected schoolchildren aged 9-11 years in the French Six Cities Study. METHODS: A cross-sectional study was carried out in Bordeaux, Clermont-Ferrand, Créteil, Marseille, Reims and Strasbourg. Parental questionnaires based on the International Study on Asthma and Allergies in Childhood (ISAAC) were used to collect information on allergic diseases and potential risk factors. Skin-prick testing to common allergens was performed to identify the existence of an allergic hypersensitivity and an exercise test was also performed to assess EIA. Height and weight were collected by trained investigators. After computing the BMI (weight/height squared), the International Obesity Task Force (IOTF) cut-offs were used to define overweight and obesity. The children were also classified as wheezing or non-wheezing. RESULTS: After adjustment for confounding factors, lifetime asthma was associated with high BMI among non-wheezing children (adjusted OR, aOR=1.98, 95% CI (1.06 to 3.70)). In addition, lifetime and past-year allergic rhinitis was associated with high BMI in wheezing children (aOR=1.63, (1.09 to 2.45) and aOR=2.20, (1.13 to 4.27)). However, high BMI was not significantly associated with eczema, SPT positivity or EIA. CONCLUSIONS: This study shows a positive association between high BMI and lifetime asthma in non-wheezing children. High BMI was also associated with lifetime and past-year allergic rhinitis. Further studies are needed to provide causal evidence.

Smoking exposure and allergic sensitization in children according to maternal allergies.

BACKGROUND: Although the negative impact of environmental tobacco smoke (ETS) on airway diseases in children is well known, the effect of ETS on allergic sensitization is still debated. OBJECTIVE: To evaluate how maternal allergies modulate the effect of tobacco exposure on allergic sensitization in childhood. METHODS: Of 9000 children in grades 4 and 5 selected in 6 cities in France, 7798 participated in a survey that consisted of an epidemiologic questionnaire, skin prick testing to common allergens, and skin examination for eczema. Tobacco exposure was obtained from parent questionnaires. RESULTS: Twenty-five percent of the children had allergic sensitization, 25.2% had eczema, 11.6% had allergic rhinitis, 9.9% had asthma, and 8.3% had exercise-induced asthma. Twenty percent of the children were exposed to tobacco in utero. Maternal exposure had a greater impact than paternal exposure on children's allergic sensitization. Prenatal exposure was more associated with sensitization than postnatal exposure. Children with maternal allergies and exposure to maternal ETS during pregnancy were at higher risk for sensitization to house dust mite (25.7% vs. 14.0%; odds ratio, 1.95; 95% confidence interval, 1.19-3.18; P = .006). In contrast, sensitization to food allergens was not associated with tobacco exposure. CONCLUSIONS: Children exposed to maternal smoking had a higher risk of sensitization to house dust mite, especially when the mothers were allergic.