There is poor agreement on definitions of different phenotypes of preschool wheezing disorders. The present Task Force proposes to use the terms episodic (viral) wheeze to describe children who wheeze intermittently and are well between episodes, and multiple-trigger wheeze for children who wheeze both during and outside discrete episodes. Investigations are only needed when in doubt about the diagnosis.Based on the limited evidence available, inhaled short-acting β₂-agonists by metered-dose inhaler/spacer combination are recommended for symptomatic relief. Educating parents regarding causative factors and treatment is useful. Exposure to tobacco smoke should be avoided; allergen avoidance may be considered when sensitisation has been established. Maintenance treatment with inhaled corticosteroids is recommended for multiple-trigger wheeze; benefits are often small. Montelukast is recommended for the treatment of episodic (viral) wheeze and can be started when symptoms of a viral cold develop.Given the large overlap in phenotypes, and the fact that patients can move from one phenotype to another, inhaled corticosteroids and montelukast may be considered on a trial basis in almost any preschool child with recurrent wheeze, but should be discontinued if there is no clear clinical benefit.Large well-designed randomised controlled trials with clear descriptions of patients are needed to improve the present recommendations on the treatment of these common syndromes.

Rationale: Atopic sensitization has long been known to be related to asthma in children, but its role in determining asthma prevalence remains to be elucidated further. Objectives: To investigate the role of atopic sensitization in the large international variation in the prevalence of childhood asthma. Methods: Cross-sectional studies of random samples of 8- to 12-year-old children (n = 1,000 per center) were performed according to the standardized methodology of Phase Two of the International Study of Asthma and Allergy in Childhood (ISAAC). Thirty study centers in 22 countries worldwide participated and reflect a wide range of living conditions, from rural Africa to urban Europe. Data were collected by parental questionnaires (n = 54,439), skin prick tests (n = 31,759), and measurements of allergen-specific IgE levels in serum (n = 8,951). Economic development was assessed by gross national income per capita (GNI). Measurements and Main Results: The prevalence of current wheeze (i.e., during the past year) ranged from 0.8% in Pichincha (Ecuador) to 25.6% in Uruguaiana (Brazil). The fraction of current wheeze attributable to atopic sensitization ranged from 0% in Ankara (Turkey) to 93.8% in Guangzhou (China). There were no correlations between prevalence rates of current wheeze and atopic sensitization, and only weak correlations of both with GNI. However, the fractions and prevalence rates of wheeze attributable to skin test reactivity correlated strongly with GNI (Spearman rank-order coefficient ρ = 0.50, P = 0.006, and ρ = 0.74, P < 0.0001, respectively). In addition, the strength of the association between current wheeze and skin test reactivity, assessed by odds ratios, increased with GNI (ρ = 0.47, P = 0.01). Conclusions: The link between atopic sensitization and asthma symptoms in children differs strongly between populations and increases with economic development.

Aims: There have been no worldwide standardised surveys of prevalence and severity of asthma, rhinoconjunctivitis and eczema in school children for 15 years. The present study aims to provide this information. Methods: Following the exact International Study of Asthma and Allergies in Childhood (ISAAC) methodology (cross-sectional questionnaire-based survey), Global Asthma Network (GAN) Phase I was carried out between 2015 and 2020 in many centres worldwide. Results: The study included 157 784 adolescents (13–14 years of age) in 63 centres in 25 countries and 101 777 children (6–7 years of age) in 44 centres in 16 countries. The current prevalence of symptoms, respectively, was 11.0% and 9.1% for asthma, 13.3% and 7.7% for rhinoconjunctivitis and 6.4% and 5.9% for eczema. The prevalence of asthma ever was 10.5% and 7.6%, hay fever ever was 15.2% and 11.1% and eczema ever was 10.6% and 13.4%, respectively. Centres in low or lower middle gross national income countries (LICs or LMICs) had significantly lower prevalence of the three disease symptoms and diagnoses (except for hay fever). In children, the prevalence of asthma and rhinoconjunctivitis symptoms was higher in boys, while the reverse occurred among adolescents. For eczema, while the prevalence among female adolescents was double that of males, there was no sex difference among children. Centre accounted for non-negligible variability in all disease symptoms (10–20%). Conclusion: The burdens of asthma, rhinoconjunctivitis and eczema vary widely among the limited number of countries studied. Although symptom prevalence is lower in LICs and LMICs, it represents a considerable burden everywhere studied.

Background Certain foods may increase or decrease the risk of developing asthma, rhinoconjunctivitis and eczema. We explored the impact of the intake of types of food on these diseases in Phase Three of the International Study of Asthma and Allergies in Childhood. Methods Written questionnaires on the symptom prevalence of asthma, rhinoconjunctivitis and eczema and types and frequency of food intake over the past 12 months were completed by 13–14-year-old adolescents and by the parents/guardians of 6–7-year-old children. Prevalence ORs were estimated using logistic regression, adjusting for confounders, and using a random (mixed) effects model. Results For adolescents and children, a potential protective effect on severe asthma was associated with consumption of fruit ≥3 times per week (OR 0.89, 95% CI 0.82 to 0.97; OR 0.86, 95% CI 0.76 to 0.97, respectively). An increased risk of severe asthma in adolescents and children was associated with the consumption of fast food ≥3 times per week (OR 1.39, 95% CI 1.30 to 1.49; OR 1.27, 95% CI 1.13 to 1.42, respectively), as well as an increased risk of severe rhinoconjunctivitis and severe eczema. Similar patterns for both ages were observed for regional analyses, and were consistent with gender and affluence categories and with current symptoms of all three conditions. Conclusions If the association between fast foods and the symptom prevalence of asthma, rhinoconjunctivitis and eczema is causal, then the findings have major public health significance owing to the rising consumption of fast foods globally.

Background The increasing prevalence of asthma and allergy might be related to diet, particularly in Western countries. A study was undertaken to assess the association between dietary factors, asthma and allergy in a large international study including objective measurements of atopy. Methods Between 1995 and 2005, cross-sectional studies were performed in 29 centres in 20 countries. Parental questionnaires were used to collect information on allergic diseases and exposure factors and data from 50 004 randomly selected schoolchildren (8–12 years, 29 579 with skin prick testing) were analysed. Random effect models for meta-analysis were applied to calculate combined ORs. Results Fruit intake was associated with a low prevalence of current wheeze in affluent (OR_adj 0.86, 95% CI 0.73 to 1.02) and non-affluent countries (OR_adj 0.71, 95% CI 0.57 to 0.88). Consumption of fish in affluent countries (OR_adj 0.85, 95% CI 0.74 to 0.97) and of cooked green vegetables in non-affluent countries (OR_adj 0.78, 95% CI 0.65 to 0.95) was associated with a lower prevalence of current wheeze. Overall, more frequent consumption of fruit, vegetables and fish was associated with a lower lifetime prevalence of asthma, whereas high burger consumption was associated with higher lifetime asthma prevalence. None of the food items was associated with allergic sensitisation. Except for fruit juice and fruit consumption, no associations were found with atopic wheeze. Food selection according to the ‘Mediterranean diet’ was associated with a lower prevalence of current wheeze and asthma ever (p_trend=0.03). Conclusion Diet is associated with wheeze and asthma but not with allergic sensitisation in children. These results provide further evidence that adherence to the ‘Mediterranean diet’ may provide some protection against wheeze and asthma in childhood.

Aims: Asthma, hay fever and eczema are three common chronic conditions. There have been no recent multi-country data on the burden of these three conditions in adults; the aims of this study are to fill this evidence gap. Methods: The Global Asthma Network Phase I is a multi-country cross-sectional population-based study using the same core methodology as the International Study of Asthma and Allergies in Childhood Phase III. It provides data on the burden of asthma, hay fever and eczema in children and adolescents, and, for the first time, in their parents/guardians. Results: Data were available from 193 912 adults (104 061 female; mean± sd age 38±7.5 years) in 43 centres in 17 countries. The overall prevalence (range) of symptoms was 6.6% (0.9–32.7%) for current wheeze, 4.4% (0.9–29.0%) for asthma ever, 14.4% (2.8–45.7%) for hay fever ever and 9.9% (1.6–29.5%) for eczema ever. Centre prevalence varied considerably both between countries and within countries. There was a moderate correlation between hay fever ever and asthma ever, and between eczema ever and hay fever ever at the centre level. There were moderate to strong correlations between indicators of the burden of disease reported in adults and the two younger age groups. Conclusion: We found evidence for a substantial burden of asthma, hay fever ever and eczema ever in the countries examined, highlighting the major public health importance of these diseases. Prevention strategies and equitable access to effective and affordable treatments for these three conditions would help mitigate the avoidable morbidity they cause.