Hospital admission for symptoms exacerbation in 2,075 infants suffering from recurrent asthma-like symptoms: (EISL-3 South America).

BACKGROUND: Contrary to what happens in children and adults, the prevalence and the factors related to hospitalisation for asthma/wheezing in infants with recurrent asthma-like symptoms are poorly known. METHODS: This study is part of the International Study of Wheezing in infants Phase 3; 2,079 infants (aged 12-18 months) with recurrent asthma-like symptoms, from 11 South American centres, were studied to determine the prevalence and the associated factors for wheezing exacerbation admission. Descriptive statistics and multivariate logistic regression were employed for analysis. RESULTS: The prevalence of admission for wheezing was 29.7% (95% CI 27.7-31.6) and was significantly associated to severe wheezing episodes (OR: 3.89; 95% CI: 2.93-5.18, p < 0.001), physician-diagnosed asthma (OR: 1.79; 95% CI: 1.33-2.41, p < 0.0001), use of inhaled corticosteroids (OR: 1.78; 95%CI: 1.38-2.29, p < 0.0001), maternal tobacco smoking during pregnancy (OR: 1.69; 95% CI: 1.19-2.39, p = 0.003) and onset of wheezing in the first trimester of life (OR: 1.30; 95% CI: 1.02-1.66, p = 0.038). Breast feeding ≥4 months (OR: 0.72; 95% CI: 0.54-0.96, p = 0.004), maternal high educational level (>12 years) (OR: 0.66; 95% CI: 0.51-0.85, p = 0.001) and total monthly household income ≥US$ 3,000 (OR: 0.34; 95% CI: 0.18-0.67, p = 0.002), were protective factors. CONCLUSIONS: Infants with recurrent asthma-like symptoms have a high rate of admissions. Tobacco smoking in pregnancy, viral respiratory illness in the first trimester of life and severe progression were risks for admissions. Improving medical management to prevent severe exacerbations, prolonging the postnatal period at home longer than 3 months, favouring breastfeeding and avoiding smoking during pregnancy may have a preventive role for admissions in infants with recurrent asthma-like symptoms.

Risk factors for wheezing in primary health care settings in the tropics.

BACKGROUND: The International Study of Wheezing in Infants (EISL) is a cross-sectional, population-based study, based on ISAAC (http://www.isaac.auckland.ac.nz). It uses a validated questionnaire on early wheezing and risk/protective factors. OBJECTIVE: To apply the EISL questionnaire regarding wheezing events in 0- to 12-month-old infants with or without atopic background searching for risk factors in the tropics. METHODS: The population was toddlers coming in for a checkup or 12-months' vaccination in primary health care clinics of a tropical city. Apart from child factors (eg, daycare attendance), we evaluated home factors (eg, air conditioning, bathroom, carpet, >6 persons, pollution) and mothers' factors (eg, education level, employment, cellphone). Data analysis was descriptive and case-control, with as cases atopic (AW) or non-atopic (NAW) wheezing children vs healthy controls. Wheezing-associated factors were evaluated using multivariate analysis, adjusted for the relation of AW/NAW with factors that were significant in prior univariate analysis. RESULTS: The study included 999 toddlers. Any wheeze: 31.3%, recurrent wheeze (≥3 episodes): 12.1%. Major risk factors for AW (OR; 95%CI) included smoking (11.39; 2.36-54.99), common cold before 3 months of life (3.72; 2.59-5.36), mold (3.48; 2.28-5.30), kitchen indoors (2.40; 1.27-4.54), and pets (1.69; 1.09-2.62); breastfeeding was almost protective. For NAW, common cold and pets were risk factors, but cesarean section (0.44; 0.23-0.82), more than 1 sibling (0.33; 0.18-0.61), and breastfeeding for longer than 3 months (0.50; 0.28-0.91) were protective. CONCLUSION: Wheezing is a health care burden. We found potential new risk factors for AW, some possibly unique for tropical climates. We suggest testing several hypotheses: could early AW be reduced in the tropics by attacking mold growth? Enhancing cooking place ventilation? Keeping pets outside? Or by postponing daycare attendance until after 4 months of age and avoiding (passive) smoking during pregnancy?

Value of bronchial reversibility to salbutamol, exhaled nitric oxide and responsiveness to methacholine to corroborate the diagnosis of asthma in children.

INTRODUCTION AND OBJECTIVES: Functional and inflammatory measures have been recommended to corroborate asthma diagnosis in schoolchildren, but the evidence in this regard is conflicting. We aimed to determine, in real-life clinical situation, the value of spirometry, spirometric bronchial reversibility to salbutamol (BDR), bronchial responsiveness to methacholine (MCT) and fractional exhaled nitric oxide (FENO), to corroborate the diagnosis of asthma in children on regular inhaled corticosteroids (ICS) referred from primary care. METHODS: One hundred and seventy-seven schoolchildren with mild-moderate persistent asthma, on treatment with regular ICS, participated in the study. Abnormal tests were defined as FENO ≥ 27 ppb, BDR (FEV1 ≥ 12%) and methacholine PC20 ≤ 4 mg/mL. RESULTS: The proportions of positive BDR, FENO and MCT, were 16.4%, 33.3%, and 87.0%, respectively. MCT was associated with FENO (p < 0.03) and BDR (p = 0.001); FENO was associated with BDR (p = 0.045), family history of asthma (p = 0.003) and use of asthma medication in the first two years of life (p = 0.004). BDR was significantly related with passive tobacco exposure (p = 0.003). CONCLUSIONS: Spirometry, BDR and BDR had a poor performance for corroborating diagnosis in our asthmatic children on ICS treatment; on the contrary, MCT was positive in most of them, which agrees with previous reports. Although asthma tests are useful to corroborate asthma when positive, clinical diagnosis remains the best current approach for asthma diagnosis, at least while better objective and feasible measurements at the daily practice are available. At present, these tests may have a better role for assessing the management and progression of the condition.

Prevalence of recurrent wheezing during the first year of life in Setúbal district, Portugal.

BACKGROUND: Recurrent wheezing during the first year of life is a major cause of respiratory morbidity worldwide, yet there are no studies on its prevalence in Portugal. OBJECTIVE: Determine the prevalence and severity of recurrent wheezing, treatments employed and other related aspects, in infants during their first year of life in Setúbal, Portugal. METHODS: This is a cross-sectional study of a random sample of infants aged 12-15 months living in Setúbal district. It uses a validated questionnaire answered by parents/caregivers at local healthcare facilities where infants attend for growth/development monitoring and/or vaccine administration. RESULTS: Among the 202 infants surveyed, 44.6% (95% CI 37.7-51.4) had at least one episode of wheezing; and 18.3% (95% CI 12.9-23.6) had recurrent wheezing. There was significant morbidity associated to recurrent wheezing in terms of severe episodes (17.3%-95% CI 12-22.5), visits to the emergency department (26.2%-95% CI 20.1-32.2) and hospital admissions (5.4%-95% CI 2.2-8.5); 10.4% (95% CI 6.1-14.6) used inhaled corticosteroids and 7.9% (95% CI 4.1-11.6) used a leukotriene receptor antagonist. CONCLUSIONS: The prevalence of recurrent wheezing in infants during the first year of life is high and is associated with significant morbidity, presenting as a relevant public health problem. An important proportion of infants' progress with a more severe condition, resulting in high use of health resources (visits to emergency department and hospitalisations). The prevalence of recurrent wheezing in this district of Portugal stays between those related in other European and Latin American Centres, suggesting that maybe some of the well-known risk factors are shared with affluent countries.

Changes in the prevalence and severity of recurrent wheezing in infants: The results of two surveys administered 7 years apart.

OBJECTIVE: To identify changes in the prevalence and severity of recurrent wheezing (RW) in infants using data obtained from two surveys administered seven years apart. METHODS: A cross-sectional, international, population-based study in infants aged 12-15 months was conducted. Data were obtained from two surveys (S1 and S2, in 2005 and 2012, respectively) using the same methodology in three large Latin American cities: Curitiba (Brazil), São Paulo (Brazil), and Santiago (Chile). RESULTS: A decrease in the overall prevalence of RW was identified between S1 (23.3%) and S2 (20.4%), p = 0.004, but it was mainly driven by the reduction observed in São Paulo; in Curitiba and Santiago, this change was not significant. The mean prevalence of the following RW severity indicators remained high and stable: severe wheezing episodes (56.9% in S1 and 54.2% in S2, p = 0.32) and emergency department (ED) visits for wheezing (S1 = 68.1%, S2 70.9%, p = 0.21). A significant increase in admissions for wheezing (21.1% to 26.7%, p = 0.004) was observed. In Curitiba and São Paulo, there were significant increases in the prevalence of physician-diagnosed asthma and in the use of inhaled corticosteroids and oral antileukotrienes. CONCLUSIONS: The prevalence and severity of RW during the first year of life remained high over time, with remarkably high rates of ED visits, admissions for wheezing and use of asthma medications. This study suggests the need for considering early asthma diagnosis and to establish an appropriate treatment in infants with recurrent and severe asthma-like symptoms.

The Global Asthma Network rationale and methods for Phase I global surveillance: prevalence, severity, management and risk factors.

The Global Asthma Network (GAN), established in 2012, followed the International Study of Asthma and Allergies in Childhood (ISAAC). ISAAC Phase One involved over 700 000 adolescents and children from 156 centres in 56 countries; it found marked worldwide variation in symptom prevalence of asthma, rhinitis and eczema that was not explained by the current understanding of these diseases; ISAAC Phase Three involved over 1 187 496 adolescents and children (237 centres in 98 countries). It found that asthma symptom prevalence was increasing in many locations especially in low- and middle-income countries where severity was also high, and identified several environmental factors that required further investigation.GAN Phase I, described in this article, builds on the ISAAC findings by collecting further information on asthma, rhinitis and eczema prevalence, severity, diagnoses, asthma emergency room visits, hospital admissions, management and use of asthma essential medicines. The subjects will be the same age groups as ISAAC, and their parents. In this first global monitoring of asthma in children and adults since 2003, further evidence will be obtained to understand asthma, management practices and risk factors, leading to further recognition that asthma is an important non-communicable disease and to reduce its global burden.

A multinational study to compare prevalence of atopic dermatitis in the first year of life.

BACKGROUND: Atopic dermatitis (AD) is common in childhood, with peak prevalence in early childhood. However, international comparisons of prevalence have focused on older children. We analysed differences in prevalence rates of AD and the associations with putative risk and protective factors, among infants in two European and two Central American countries. METHODS: In 1-yr old infants participating in the International Study of Wheezing in Infants (EISL), prevalence of AD and putative risk and protective factors were assessed by a questionnaire applied to parents. For each risk/protective factor summary, odds ratios with 95% confidence intervals were calculated by means of random effects meta-analysis. RESULTS: Data from 9803 infants were analysed. AD prevalence varied from 10.6% (Valencia, Spain) to 28.2% (San Pedro Sula, Honduras). Average AD prevalences were lower in Europe (14.2%) than in Central America (18.2%, p < 0.01). Consistent with older children, presence of siblings decreased (OR 0.82 [0.72-0.94]), whereas family history of asthma (OR 1.32 [1.10-1.59]), rhinitis (OR 1.33 [1.14-1.54]) and atopic dermatitis (OR 2.40 [1.89-3.05]) increased the risk of infantile AD. However, gender, family size, breastfeeding and socio-economic status were not associated with AD prevalence. CONCLUSIONS: This study shows almost threefold differences in the prevalence of AD in infancy between countries. Risk and protective factors involved in the expression of infantile AD differ from those in older children, possibly suggesting a different pathophysiology. There is a need for additional international epidemiological surveys on AD in young children, the peak prevalence age of this condition.

[Prevalence of atopy in 1,199 asthmatic children from southern Santiago, Chile]. / Prevalencia y perfil de sensibilización a aeroalérgenos en 1.199 niños asmáticos: serie consecutiva de casos.

BACKGROUND: The prevalence of atopy in asthmatic children is widely variable around the world as demonstrated by large multicentric international studies. AIM: To determine the prevalence of atopy, defined as a positive reaction to one or more allergens in the skin prick test (SPT), in children with persistent asthma. MATERIAL AND METHODS: We studied 1,199 children (54% male), aged between 4 and 16 years with confirmed diagnosis of asthma and followed at a Department of Pediatric Respiratory Medicine, between 2006 and 2011. SPT was performed according to international recommendations using standardized aeroallergens, in the forearm. A positive reaction was defined as a wheal ≥ 3 mm to one or more allergens. RESULTS: The overall prevalence of atopy (positive SPT) was 49.4% (95% confidence interval (CI) 46.5-52.2) and there was a significant trend towards a higher prevalence with increasing age (p < 0.01). The main allergens with positive reactions were Dermatophagoides with 24.9% (95% CI 26.7-31.9), grass 24.0% (95% CI 21.6-26.5), weeds 19.0% (95% CI 16.9-21.4), cat 17.7% (95% CI 15.4-20.2), and Alternaria with 11.0% (95% CI 9.1-13.1). Sixty five percent of positive children reacted to one or more allergens. There were no adverse reactions. CONCLUSIONS: In the southern metropolitan area of Santiago de Chile, half of children with asthma are sensitized to common aeroallergens.

Risk factors for wheezing disorders in infants in the first year of life living in São Paulo, Brazil.

The objective of this study was to identify risk factors for wheezing disorders in the first year of life in infants living in São Paulo (SP), Brazil, applying the standardized protocol of the Estudio Internacional de sibilancia en lactentes-Phase 1. A total of 1014 parents or caregivers of infants, who attended for routine evaluation and immunization in public health centers were interviewed in Southern SP city. Risk factors significantly associated with recurrent wheezing were: history of previous pneumonia, daycare attendance, consumption of processed food, presence of a cat at home, more than five upper respiratory infection (URI) episodes and the first URI before the age of sixth month. Most of these risk factors for wheezing can be avoided or controlled. Prospective studies on wheezing, especially in children with a severe presentation, are needed to analyze the impact of these risk factors and the effect of preventive actions.

Allergic sensitization in low-income urban children: relationship with current symptoms of asthma and rhinitis.

BACKGROUND: Recent information on the prevalence of allergic sensitization (AS) in children from low-income urban areas is limited. METHODS: We conducted a cross-sectional, randomized, population-based study to determine the prevalence of AS, and its relationship with asthma and rhinitis in low-income schoolchildren in Santiago, Chile. The parents answered a standardized questionnaire on respiratory symptoms, and a skin prick test (SPT) for common aeroallergens was performed on all children. RESULTS: In the 545 schoolchildren studied (mean age 8.3 ± 0.9 years), the prevalence of positive SPT was 25.5%. The current prevalence of asthma, rhinitis, and rhinoconjunctivitis was 20%, 43.4%, and 27.8%, respectively. SPT was positive in 30.6%, 32.8%, and 38.0% of children with current asthma, rhinitis, and rhinoconjunctivitis, respectively. Positive SPT was significantly associated with rhinitis and rhinoconjunctivitis (p < 0.001) but not with asthma. Breastfeeding for at least 4 months was significantly protective against AS (odds ratio [OR] 0.48, 95% confidence interval [CI] 0.26-0.78; p = 0.008); no other factor studied was associated with AS. CONCLUSIONS: The prevalence of AS was low; less than 40% of children with current asthma, rhinitis, or rhinoconjunctivitis symptoms evidenced AS. The prevalence of non-atopic asthma and rhinitis is consistent with previous findings in children from low-income urban areas. Other environmental factors, such as the high burden of respiratory infections and environmental pollution, might be more critical than atopy for developing asthma and rhinitis in schoolchildren from deprived urban areas.

INTRODUCCIÓN: La información reciente sobre la prevalencia de sensibilización alérgica (SA) en niños de áreas urbanas de bajos recursos es limitada. MÉTODOS: Se realizó un estudio transversal, aleatorio, a nivel poblacional, para determinar la prevalencia de SA y su relación con asma y rinitis en escolares de bajos recursos en Santiago de Chile. Los padres respondieron un cuestionario estandarizado de síntomas respiratorios y se realizaron pruebas cutáneas (PC) para alérgenos comunes en los niños. RESULTADOS: En los 545 escolares estudiados (media de edad 8.3 ± 0.9 años) la prevalencia de PC positivas fue del 25.5%. La prevalencia actual de asma, rinitis y rinoconjuntivitis fue del 20%, 43.4% y 27.8%, respectivamente. Las PC fueron positivas en el 30.6%, 32.8% y 38.0% de los niños con síntomas actuales de asma, rinitis y rinoconjuntivitis, respectivamente. La rinitis y la rinoconjuntivitis se asociaron significativamente con PC positiva (p < 0.001), pero no el asma. La lactancia materna por al menos cuatro meses protegió significativamente contra SA (razón de momios [RM] 0.48, intervalo de confianza [IC] 95% 0.26-0.78; p = 0.008); ningún otro factor estudiado se asoció con SA. CONCLUSIONES: La prevalencia de SA fue baja; menos del 40% de los niños con síntomas actuales de asma, rinitis o rinoconjuntivitis evidenció SA. La alta prevalencia de asma y rinitis no atópicas concuerda con hallazgos previos en niños de áreas urbanas de bajos ingresos. Otros factores ambientales como la alta carga de infecciones respiratorias y contaminación ambiental podrían ser más importantes que la atopia para el desarrollo de asma y rinitis en escolares de áreas urbanas desfavorecidas.

Prevalence and Determinants of Tobacco Smoking Among Low-Income Urban Adolescents.

Background: Tobacco-smoking in children is one of the most crucial public health concerns, which could be highly prevalent in underprivileged populations. Methods: A cross sectional, random sampling survey was conducted to determine the prevalence of current tobacco-smoking and related risk factors among adolescents living in a low-income area of Santiago de Chile. Results: Of the 2,747 adolescents participating in the study, 24.0% [95% confidence interval (CI) 22.3-25.5] were current smokers, with no significant difference between girls and boys. Factors associated with current smoking were as follows: positive attitude to smoking cigarettes offered by peers [odds ratio (OR) 8.0; 95% CI 5.7-11.3, P < 0.001], having smoking best friends (OR 4.0; 95% CI 2.6-6.0, P < 0.001), and passive smoking in the house (OR 1.9; 95% CI 1.2-3.1, P = 0.008). A total of 16.8% (95% CI 11.4-18.2) of children had smoked an entire cigarette at the age of ≤12, and 62.3% (95% CI, 60.5-64.1) were passive smokers at home. Regarding nonsmoking children, 52.4% (95% CI 49.74-55.06) were exposed to tobacco smoke at home. Conclusion: The prevalence of current tobacco-smoking in adolescents is high and increasing compared to previous studies undertaken in the selected low-resourced area. Two-thirds of children who started smoking before the age of 12 years were current smokers at the time of the survey, highlighting the prevalence of the powerful addiction generated and the need for better preventive strategies against tobacco-smoking for children living in low-resource communities.

Associated factors with recurrent wheezing in infants: is there difference between the sexes?

OBJECTIVE: Identify associated factors for recurrent wheezing (RW) in male and female infants. METHODS: Cross-sectional multicentric study using the standardized questionnaire from the Estudio Internacional sobre Sibilancias en Lactantes (EISL). The questionnaire was applied to parents of 9345 infants aged 12-15 months at the time of immunization/routine visits. RESULTS: One thousand two hundred and sixty-one (13.5%) males and nine hundred sixty-three (10.3%) females have had RW (≥3 episodes), respectively (p10 colds episodes (OR = 3.46; IC 95% 2.35-5.07), air pollution (OR = 1.33; IC 95% 1.12-1.59), molds at home (OR = 1.23; IC 95% 1.03-1.47), Afro-descendants (OR = 1.42; IC 95% 1.20-1.69), bronchopneumonia (OR = 1.41; IC; 1.11-1.78), severe episodes of wheezing in the first year (OR = 1.56; IC 95% 1.29-1.89), treatment with bronchodilators (OR = 1.60; IC 95% 1.22-2,1) and treatment with oral corticosteroids (OR = 1,23; IC 95% 0.99-1,52). Associated factors for RW for females were passive smoking (OR = 1.24; IC 95% 1.01-1,51), parents diagnosed with asthma (OR = 1.32; IC 95% 1,08-1,62), parents with allergic rhinitis (OR = 1.26; IC 95% 1.04-1.53), daycare attendance (OR = 1.48; IC 95% 1.17-1,88), colds in the first 6 months of life (OR = 2.19; IC 95% 1.69-2.82), personal diagnosis of asthma (OR = 1.84; IC 95% 1.39-2.44), emergency room visits (OR = 1.78; IC 95% 1.44-2.21), nighttime symptoms (OR = 2.89; IC 95% 2.34-3.53) and updated immunization (OR = 0.62; IC 95% 0.41-0.96). CONCLUSION: There are differences in associated factors for RW between genders. Identification of these differences could be useful to the approach and management of RW between boys and girls.

International prevalence of recurrent wheezing during the first year of life: variability, treatment patterns and use of health resources.

BACKGROUND: Recurrent wheezing (RW) during the first year of life is a major cause of respiratory morbidity worldwide, yet there are no studies on its prevalence at an international level. A study was undertaken to determine the prevalence of RW in infants during their first year of life in affluent and non-affluent localities. METHODS: This international population-based study was performed in random samples of infants aged 12-15 months from 17 centres in Latin America and Europe. It uses a validated questionnaire answered by parents at the primary care health clinics where infants attend for growth/development monitoring and/or vaccine administration. RESULTS: Among the 30,093 infants surveyed, 45.2% (95% CI 44.7% to 45.8%) had at least one episode of wheezing and 20.3% (95% CI 19.8% to 20.7%) had RW. The mean prevalence of RW in Latin American and European centres was 21.4% (95% CI 20.9% to 21.9%) and 15.0% (95% CI 14.0% to 15.9%), respectively (p<0.001). There was significant morbidity associated with RW in terms of severe episodes (59.4%), visits to the emergency department (71.1%) and hospital admissions (26.8%); 46.1% used inhaled corticosteroids. CONCLUSIONS: The prevalence of RW in infants during the first year of life is high and varies between localities. A significant proportion of infants progress to a more severe condition which results in high use of health resources (visits to emergency department and hospitalisations). The prevalence of RW is lower and less severe in European than in Latin American centres, suggesting there is a higher risk for the disease in developing areas.

Which population level environmental factors are associated with asthma, rhinoconjunctivitis and eczema? Review of the ecological analyses of ISAAC Phase One.

The International Study of Asthma and Allergies in Childhood (ISAAC) Phase One showed large worldwide variations in the prevalence of symptoms of asthma, rhinoconjunctivitis and eczema, up to 10 to 20 fold between countries. Ecological analyses were undertaken with ISAAC Phase One data to explore factors that may have contributed to these variations, and are summarised and reviewed here.In ISAAC Phase One the prevalence of symptoms in the past 12 months of asthma, rhinoconjunctivitis and eczema were estimated from studies in 463,801 children aged 13 - 14 years in 155 centres in 56 countries, and in 257,800 children aged 6-7 years in 91 centres in 38 countries. Ecological analyses were undertaken between symptom prevalence and the following: Gross National Product per capita (GNP), food intake, immunisation rates, tuberculosis notifications, climatic factors, tobacco consumption, pollen, antibiotic sales, paracetamol sales, and outdoor air pollution.Symptom prevalence of all three conditions was positively associated with GNP, trans fatty acids, paracetamol, and women smoking, and inversely associated with food of plant origin, pollen, immunisations, tuberculosis notifications, air pollution, and men smoking. The magnitude of these associations was small, but consistent in direction between conditions. There were mixed associations of climate and antibiotic sales with symptom prevalence.The potential causality of these associations warrant further investigation. Factors which prevent the development of these conditions, or where there is an absence of a positive correlation at a population level may be as important from the policy viewpoint as a focus on the positive risk factors. Interventions based on small associations may have the potential for a large public health benefit.

Prevalence of rhinitis-related symptoms in Latin American children - results of the International Study of Asthma and Allergies in Childhood (ISAAC) phase three.

The aim of this study was to evaluate the prevalence of rhinitis-related symptoms among children living in different parts of Latin America (LA) considering all centers involved in ISAAC Phase Three (Ph3). 93,851 children (6-7 yr-old) from 35 centers in 14 LA countries and 165,917 adolescents (13-14 yr-old) from 56 centers in 17 LA countries were enrolled. The mean prevalence rate of current rhinoconjunctivitis was 12.7% and ranged from 5.5% in Rosario City (Argentina) to 21.2% in Caracas (Venezuela) for the schoolchildren. The mean prevalence rate of current rhinoconjunctivitis was 18.5% and ranged from 7.1% in Cuernavaca (México) to 45.1% in Asunción (Paraguay) for the adolescents. These indexes were among the higher observed during ISAAC Ph3. In general the prevalence of rhinitis-related symptoms was higher among the Spanish speaking centers. Environmental risk factors must be evaluated in order to explain the differences observed even in centers from the same country.

International study of wheezing in infants: risk factors in affluent and non-affluent countries during the first year of life.

Risk factors for wheezing during the first year of life (a major cause of respiratory morbidity worldwide) are poorly known in non-affluent countries. We studied and compared risk factors in infants living in affluent and non-affluent areas of the world. A population-based study was carried out in random samples of infants from centres in Latin America (LA) and Europe (EU). Parents answered validated questionnaires referring to the first year of their infant's life during routine health visits. Wheezing was stratified into occasional (1-2 episodes, OW) and recurrent (3 + episodes, RW). Among the 28687 infants included, the most important independent risk factors for OW and RW (both in LA and in EU) were having a cold during the first 3 months of life [OR for RW 3.12 (2.60-3.78) and 3.15 (2.51-3.97); population attributable fraction (PAF) 25.0% and 23.7%]; and attending nursery school [OR for RW 2.50 (2.04-3.08) and 3.09 (2.04-4.67); PAF 7.4% and 20.3%]. Other risk factors were as follows: male gender, smoking during pregnancy, family history of asthma/rhinitis, and infant eczema. Breast feeding for >3 months protected from RW [OR 0.8 (0.71-0.89) in LA and 0.77 (0.63-0.93) in EU]. University studies of mother protected only in LA [OR for OW 0.85 (0.76-0.95) and for RW 0.80 (0.70-0.90)]. Although most risk factors for wheezing are common in LA and EU; their public health impact may be quite different. Avoiding nursery schools and smoking in pregnancy, breastfeeding babies >3 months, and improving mother's education would have a substantial impact in lowering its prevalence worldwide.