Prevalence and factors linked to allergic rhinitis in 10 and 11-year-old children in Almería. Isaac Phase II, Spain

BACKGROUND

Allergic rhinitis affects 10-30% of children in developed countries and has increased in frequency over the last few decades, probably due to changes in the environment and life style.

AIM

To assess the prevalence, severity, and factors linked to rhinitis in 10 and 11-year-old children from Almeria (Spain).

METHODS

As part of ISAAC II, a cross-sectional survey was conducted among a representative sample of 1143 schoolchildren in spring and autumn of 2001, using homologated questionnaires and skin-prick testing.

RESULTS

The overall prevalence of rhinitis and rhinoconjunctivitis were 38.9% and 24.8%, respectively, 17.9% had medically diagnosed rhinitis. During the previous year symptoms disturbed daily activities and school attendance in some measure in 40% and 26% of children with rhinitis, respectively. The risk factors found in the multiple logistic regression analysis were atopy (OR 2.57; 95% CI 1.92-3.42); cat contact at home during first year of life (OR 2.4 95% CI 1.13-5.12); prior medical diagnosis of asthma (OR 2.2; 95% CI 1.22-4.02); nocturnal cough in absence of colds (OR 1.9; 95% CI 1.25-2.97); diagnosis of rhinitis in one of the parents (OR 1.8; 95% CI 1.31-2.59); wheezing at any time (OR 1.6; 95% CI 1.18-2.28); and nursery school attendance (OR 1.5; 95% CI 1.21-2.5).

CONCLUSIONS

The prevalence of rhinitis found is superior to that of other centres participating in the ISAAC Phases I and II, and coexists with asthma and eczema in many children. The independent risk factors associated to rhinitis are in accordance with previous reports.

A multi-centre study of candidate genes for wheeze and allergy: the International Study of Asthma and Allergies in Childhood Phase 2

BACKGROUND

Common polymorphisms have been identified in genes suspected to play a role in asthma. We investigated their associations with wheeze and allergy in a case-control sample from Phase 2 of the International Study of Asthma and Allergies in Childhood.

METHODS

We compared 1105 wheezing and 3137 non-wheezing children aged 8-12 years from 17 study centres in 13 countries. Genotyping of 55 candidate single nucleotide polymorphisms (SNPs) in 14 genes was performed using the Sequenom System. Logistic regression models were fitted separately for each centre and each SNP. A combined per allele odds ratio and measures of heterogeneity between centres were derived by random effects meta-analysis.

RESULTS

Significant associations with wheeze in the past year were detected in only four genes (IL4R, TLR4, MS4A2, TLR9, P<0.05), with per allele odds ratios generally <1.3. Variants in IL4R and TLR4 were also related to allergen-specific IgE, while polymorphisms in FCER1B (MS4A2) and TLR9 were not. There were also highly significant associations (P<0.001) between SPINK5 variants and visible eczema (but not IgE levels) and between IL13 variants and total IgE. Heterogeneity of effects across centres was rare, despite differences in allele frequencies.

CONCLUSIONS

Despite the biological plausibility of IgE-related mechanisms in asthma, very few of the tested candidates showed evidence of association with both wheeze and increased IgE levels. We were unable to confirm associations of the positional candidates DPP10 and PHF11 with wheeze, although our study had ample power to detect the expected associations of IL13 variants with IgE and SPINK5 variants with eczema.

Effect of breastfeeding on asthma, lung function and bronchial hyperreactivity in ISAAC Phase II

The association between breastfeeding and wheezing, lung function and atopy was evaluated in the International Study of Asthma and Allergy in Childhood (ISAAC) Phase II. Cross-sectional studies were performed in 27 centres in 20 countries. Information on disease and exposure factors was collected by parental questionnaires. Data from 54,000 randomly selected school children (aged 8-12 yrs, 31,759 with skin prick testing) and a stratified subsample (n = 4,888) were used for testing the correlation of breastfeeding with bronchial hyperreactivity and lung function. Random effect models for meta-analysis were applied to calculate combined odds ratios (ORs). Any breastfeeding was associated with less wheeze both in affluent (adjusted OR (OR(adj)) 0.87, 95% confidence interval (CI) 0.78-0.97) and nonaffluent countries (OR(adj) 0.80, 95% CI 0.68-0.94). Further analyses revealed that this was true only for nonatopic wheeze in nonaffluent countries (OR(adj) 0.69, 95% CI 0.53-0.90). Breastfeeding was not associated with atopic wheeze and objective measures of allergy in both affluent and nonaffluent countries. In contrast, breastfeeding was associated with higher predicted forced expiratory volume in one second in affluent countries only (mean ratio 1.11, 95% CI 1.02-1.20). Breastfeeding is associated with protection against nonatopic wheeze, which becomes particularly evident in nonaffluent countries. Overall, breastfeeding was not related to any measure of allergy. These findings may explain some of the controversy regarding breastfeeding, since the direction of the association with breastfeeding depends on the predominating wheeze phenotype (e.g. atopic, nonatopic).

How the presence of rhinoconjunctivitis and the severity of asthma modify the relationship between obesity and asthma in children 6-7 years old

BACKGROUND

The association between asthma and obesity in children, and the effect modification of allergy on this association have not been fully established. Aims The objective of the study was to know the effect modification of the severity of asthma and of the coexistence of rhinoconjunctivitis (RC) in the relationship between obesity and asthma.

METHODS

A cross-sectional study of 17 145 schoolchildren 6-7 years old from eight Spanish cities who had completed information on height and weight of the ISAAC phase III questionnaire, which also included questions about asthma and RC symptoms and on various risk factors. Body mass index (BMI) was used to define obesity according to international standards. Two different logistic regressions, using current occasional asthma (COA) and current severe asthma (CSA) as dependent variables, were made stratifying for gender and for the coexistence of RC and controlling for age, older and younger siblings, exercise, mother's education, truck traffic, cat/dog during the first year of life and smoking father or mother.

RESULTS

Obesity was a risk factor of CSA without RC, both for boys (1.92, CI 95% 1.13-3.25) and for girls (2.99, CI 95% 1.68-5.32). Every BMI unit increment increased by 6.7% the risk of CSA without RC in boys and by 12.4% in girls. Obesity was not a risk factor for CSA with RC. The association between COA and obesity was weaker and the coexistence of RC did not modify it greatly.

CONCLUSIONS

Obese schoolchildren are more at risk of suffering from non-allergic asthma than the non-obese subjects.

[Geographic variation in the prevalence of asthma symptoms in Spanish children and adolescents. International Study of Asthma and Allergies in Childhood (ISAAC) Phase 3, Spain]

OBJECTIVE

To analyze geographic variations in the prevalence of symptoms related to asthma in Spanish children and adolescents.

POPULATION AND METHODS

In 2001 and 2002, the Spanish arm of the International Study of Asthma and Allergies in Childhood (ISAAC) Phase 3 collected information on 28 445 children in the age bracket of 6-7 years in 10 metropolitan areas (A Coruña, Asturias, Barcelona, Bilbao, Cartagena, Castellón, Madrid, Pamplona, San Sebastián, and Valencia) and on 31 257 adolescents in the bracket 13-14 years in 11 areas (the previously named areas plus Valladolid). An asthma symptom questionnaire was filled in by parents or the adolescents themselves. Differences in symptoms between geographic areas were analyzed by fitting a logistic regression model. The relationship between symptoms and age was analyzed by linear correlation.

RESULTS

The prevalence of recent wheezing (last 12 months) ranged from 7.1% to 12.9% among 6-7-year-olds and from 7.1% to 15.3% among the 13-14-year-olds. The greatest risk of recent wheezing was observed for children in A Coruña (odds ratio [OR] =1.96 in comparison with the area of lowest prevalence; 95% confidence interval [CI], 1.65-2.33) and Bilbao (OR=1.83; 95% CI, 1.54-2.18) and for adolescents in A Coruña (OR=2.38; 95% CI, 2.04-2.79) and Asturias (OR=2.37; 95% CI, 2.03-2.77). A strong correlation (r=0.72) was observed between the prevalence of recent wheezing and age in each of the geographic areas.

CONCLUSIONS

Considerable geographic variation in the prevalence of asthma symptoms can be seen in Spain even among young children. Symptoms are more frequent in children and adolescents who live on the Spain s northern Atlantic coast.