Asthma in Latin America: a public heath challenge and research opportunity

Factors associated with asthma symptoms in Colombian subpopulations aged 1 to 17 and 18 to 59: Secondary analysis of the study "Prevalence of asthma and other allergic diseases in Colombia 2009-2010"

BACKGROUND

Asthma, a chronic inflammatory lung disease, is one of the leading causes of disability, demands on health resources, and poor quality of life. It is necessary to identify asthma-related risk factors to reduce the presence and development of symptoms.

OBJECTIVE

This study aimed to explore the association of multiple possible factors with asthma symptoms in two subpopulations, children, adolescents, and adults, in six cities in Colombia.

MATERIALS AND METHODS

This was an observational analytical case-control study based on a cross-sectional study conducted as a secondary analysis of the prevalence of asthma and other allergic diseases in Colombia during 2009 and 2010. Weighted logistic regressions were conducted for each population.

RESULTS

Out of the 5978 subjects in the cross-sectional survey, 747 were identified as cases, and 3109 were identified as controls. The prevalence of asthma was 30.8% in the child and adolescent population and 14.7% in the adult population. Among the various factors studied, those associated with asthma symptoms in children/adolescents were: a family history of asthma (OR 2.4; 95% CI 1.3-4.7) and rhinitis (OR 2.0; 95% CI 1.1-3.6); acetaminophen consumption at least once a month (OR 3.6; 95% CI 2.1-6.2); and the presence of birds at home (OR 2.0; 95% CI 1.1-3.8). Regarding food consumption: fruit consumption (OR 3.8; 95% CI 1.1-12.7). In adults, the factors that showed significant association were: a family history of allergic diseases (rhinitis OR 3.3; 95% CI 2.3-4.6), atopic eczema (OR 4.4; 95% CI 2.8-7.0), or asthma (OR 1.8;95% CI 1.3-2.6); acetaminophen consumption at least once a month (OR 2.0; 1.5-2.8); the presence of dogs at home (OR 1.4;95% CI 1.03-1.8), exposure to second-hand smoke (OR 1.7; 95% CI 1.2-2.2), and exposure to exhaust fumes during the day (OR 1.7; 95% CI 1.04-2.7).

CONCLUSIONS

Our findings suggest that different cultural, environmental, and family factors are associated with asthma symptoms in children and adolescents, and these associations are evident in both males and females.

Associations between psychosocial stress, child's anxiety, and lung function in mid-childhood

BACKGROUND

Reducing the risk of respiratory disease during the plastic stages of lung development could have long-term health impacts. Psychosocial stress has been previously linked to adverse childhood respiratory outcomes, but the influence of child's anxiety and sex differences has not been completely elucidated.

OBJECTIVE

To evaluate the association among maternal stress, child anxiety, and lung function in children and to explore differences by sex.

METHODS

Cross-sectional analyses included 294 mother-child pairs from the Programming Research in Obesity, Growth, Environment and Social Stressors (PROGRESS) birth cohort in Mexico City. Children's lung function was tested once at ages 8 to 13 years of age, and height- and sex-adjusted z-scores were estimated for forced vital capacity, forced expiratory volume in 1 second, forced expiratory volume in 1 second/forced vital capacity and forced expiratory flow between 25% and 75%. Maternal stress was assessed through the Crisis in Family Systems-Revised (CRISYS-R) survey, used to report negative life events experienced in the past 6 months and dichotomized at the median (<3 and ≥3). Child's self-reported anxiety was assessed using the Revised Children's Manifest Anxiety Scale short form and dichotomized at the clinically relevant cutoff (T-score ≥ 60). The association among maternal stress, child anxiety, and lung function outcomes was evaluated using linear models. Effect modification by sex was evaluated with interaction terms and in stratified analyses.

RESULTS

We did not find any association between maternal stress and any lung function outcome. Clinically elevated child anxiety symptoms were associated with lower forced expiratory volume in 1 second (β = -0.36, 95% CI -0.69 to -0.02). We found no evidence of effect modification by sex.

CONCLUSION

Results highlight the importance of considering childhood mental health in relation to lung function outcomes.

Association between a western diet and asthma among children and adolescents

Several risk factors including environmental exposures, socioeconomic status, and dietary factors including dietary patterns have been considered for childhood Asthma. The present study tried to examine the association between a western-style pattern and the likelihood of asthma and its symptoms in Yazd, Iran. In the present cross-sectional study, dietary intakes of elementary and high-school children were obtained through a validated GAN questionnaire. The GAN questionnaire, derived from the ISAAC questionnaire was used to assess the symptoms of allergic diseases and their related risk factors. A western dietary pattern score considered 9 food groups including chicken eggs, margarine, butter, sugar, fast foods, soft drinks, snacks, sauce, and chocolate. In total 7667 children aged 10.9 ± 3.35 years were included in the current investigation. Boys with higher adherence to western dietary pattern had a higher risk of wheezing in the past 12 months (OR 1.37, 5% CI 1.01-1.87, P = 0.04) and this association was also observed in the whole population (OR 1.30, 5% CI 1.05-1.60, P = 0.01). However, after adjustment for confounders this relation did not remain significant in boys. Our results support the hypothesis that a western dietary pattern is associated with an increased risk of wheezing in the past 12 months in children with asthma. Future prospective studies are needed to confirm this finding.

Delayed acquisition of airway commensals in antibiotic naïve children and its relationship with wheezing in rural Ecuador

Introduction

The hygiene hypothesis identified a relationship between living in rural areas and acquiring protective environmental factors against the development of asthma and atopy. In our previous study, we found a correlation between particular bacterial species and early-onset wheezing in infants from the rural tropics of Ecuador who were corticosteroid-naïve and had limited antibiotic exposure. We now describe a longitudinal study of infants conducted to determine the age-related changes of the microbiome and its relationship with wheezing.

Methods

We performed an amplicon sequencing of the 16S rRNA bacterial gene from the oropharyngeal samples obtained from 110 infants who had a history of recurrent episodic wheezing sampled at different ages (7, 12, and 24 months) and compared it to the sequencing of the oropharyngeal samples from 150 healthy infants sampled at the same time points. Bioinformatic analyses were conducted using QIIME and R.

Results

As expected, the microbiota diversity consistently increased as the infants grew older. Considering age-based microbiota changes, we found that infants with wheeze had significantly lower species richness than the healthy infants at 7 months, but not at 12 or 24 months. Most of the core and accessory organisms increased in abundance and prevalence with age, except for a few which decreased. At 7 months of age, infants with wheeze had notably higher levels of a single Streptococcus operational taxonomic unit and core microbiota member than controls.

Conclusions

In a cohort with limited antibiotic and corticosteroid use, a progressively more complex and diverse respiratory microbial community develops with age. The respiratory microbiota in early life is altered in infants with wheeze, but this does not hold true in older infants.

Global, regional, and national burden of allergic disorders and their risk factors in 204 countries and territories, from 1990 to 2019: A systematic analysis for the Global Burden of Disease Study 2019

BACKGROUND

Asthma and atopic dermatitis (AD) are chronic allergic conditions, along with allergic rhinitis and food allergy and cause high morbidity and mortality both in children and adults. This study aims to evaluate the global, regional, national, and temporal trends of the burden of asthma and AD from 1990 to 2019 and analyze their associations with geographic, demographic, social, and clinical factors.

METHODS

Using data from the Global Burden of Diseases (GBD), Injuries, and Risk Factors Study 2019, we assessed the age-standardized prevalence, incidence, mortality, and disability-adjusted life years (DALYs) of both asthma and AD from 1990 to 2019, stratified by geographic region, age, sex, and socio-demographic index (SDI). DALYs were calculated as the sum of years lived with disability and years of life lost to premature mortality. Additionally, the disease burden of asthma attributable to high body mass index, occupational asthmagens, and smoking was described.

RESULTS

In 2019, there were a total of 262 million [95% uncertainty interval (UI): 224-309 million] cases of asthma and 171 million [95% UI: 165-178 million] total cases of AD globally; age-standardized prevalence rates were 3416 [95% UI: 2899-4066] and 2277 [95% UI: 2192-2369] per 100,000 population for asthma and AD, respectively, a 24.1% [95% UI: -27.2 to -20.8] decrease for asthma and a 4.3% [95% UI: 3.8-4.8] decrease for AD compared to baseline in 1990. Both asthma and AD had similar trends according to age, with age-specific prevalence rates peaking at age 5-9 years and rising again in adulthood. The prevalence and incidence of asthma and AD were both higher for individuals with higher SDI; however, mortality and DALYs rates of individuals with asthma had a reverse trend, with higher mortality and DALYs rates in those in the lower SDI quintiles. Of the three risk factors, high body mass index contributed to the highest DALYs and deaths due to asthma, accounting for a total of 3.65 million [95% UI: 2.14-5.60 million] asthma DALYs and 75,377 [95% UI: 40,615-122,841] asthma deaths.

CONCLUSIONS

Asthma and AD continue to cause significant morbidity worldwide, having increased in total prevalence and incidence cases worldwide, but having decreased in age-standardized prevalence rates from 1990 to 2019. Although both are more frequent at younger ages and more prevalent in high-SDI countries, each condition has distinct temporal and regional characteristics. Understanding the temporospatial trends in the disease burden of asthma and AD could guide future policies and interventions to better manage these diseases worldwide and achieve equity in prevention, diagnosis, and treatment.

Over-prescription of short-acting β2-agonists is associated with poor asthma outcomes: results from the Latin American cohort of the SABINA III study

OBJECTIVE

Short-acting β₂-agonist (SABA) over-reliance is associated with poor asthma outcomes. As part of the SABA Use IN Asthma (SABINA) III study, we assessed SABA prescriptions and clinical outcomes in patients from six Latin American countries.

METHODS

In this cross-sectional study, data on disease characteristics/asthma treatments were collected using electronic case report forms. Patients (aged ≥12 years) were classified by investigator-defined asthma severity (guided by the 2017 Global Initiative for Asthma) and practice type (primary/specialist care). Multivariable regression models analyzed the associations between SABA prescriptions and clinical outcomes.

RESULTS

Data from 1096 patients (mean age, 52.0 years) were analyzed. Most patients were female (70%), had moderate-to-severe asthma (79.4%), and were treated by specialists (87.6%). Asthma was partly controlled/uncontrolled in 61.5% of patients; 47.4% experienced ≥1 severe exacerbation in the previous 12 months. Overall, 39.8% of patients were prescribed ≥3 SABA canisters in the preceding 12 months (considered over-prescription). SABA canisters were purchased over the counter (OTC) by 17.2% of patients, of whom 38.8% purchased ≥3 canisters in the 12 months prior. Of patients who purchased SABA OTC, 73.5% were prescribed ≥3 SABA canisters. Higher SABA prescriptions (vs. 1 - 2 canisters) were associated with an increased incidence rate of severe exacerbations (ranging from 1.31 to 3.08) and lower odds ratios of having at least partly controlled asthma (ranging from 0.63 to 0.15).

CONCLUSIONS

SABA over-prescription was common in Latin America, highlighting the need for urgent collaboration between healthcare providers and policymakers to align clinical practices with the latest evidence-based recommendations to address this public health concern.

Scientific Research in Ecuador: A Bibliometric Analysis

Ecuador has shown a growth in its scientific production since 2011, representing 85% of the total historical production. These investigations are reflected in scientific publications, which address world interest topics and serve as a link for the university, business, and society. This work aims to analyze the scientific production generated by Ecuador in the period of 1920–2020 using bibliometric methods to evaluate its intellectual structure and performance. The methodology applied in this study includes: (i) terms definition and search criteria; (ii) database selection, initial search, and document compilation; (iii) data extraction and software selection; and finally, (iv) analysis of results. The results show that scientific production has been consolidated in 30,205 documents, developed in 27 subject areas, in 13 languages under the contribution of 84 countries. This intellectual structure is in harmony with the global context when presenting research topics related to “Biology and regional climate change”, “Higher education and its various approaches”, “Technology and Computer Science”, “Medicine”, “Energy, food and water”, and ”Development and applications on the Web”. Topics framed in the Sustainable Development Goals (SDGs), sustainability, climate change, and others. This study contributes to the academic community, considering current re-search issues and global concerns, the collaboration between universities and countries that allow establishing future collaboration links.

Asthma, rhinitis and eczema symptoms in Quito, Ecuador: a comparative cross-sectional study 16 years after ISAAC

Background

In 2003, the International Study of Asthma and Allergies in Childhood (ISAAC) estimated the prevalence of asthma, rhinitis and eczema symptoms in Quito, Ecuador. Since then, no update of this study has been done in the last years. This study examined changes in the prevalence of asthma–rhinitis–eczema symptoms over a 16 years period in Quito and explored possible risk factors.

Methods

We conducted a comparative cross-sectional study in an adolescent population following the Global Asthma Network (GAN) methodology. A written questionnaire was used to explore symptoms of asthma–rhinitis–eczema. We calculated the prevalence and 95% CIs for each of the symptoms and compared them with the ISAAC results. We conducted bivariate and multivariate analysis using logistic regression to identify possible risk factors for recent wheeze, rhinitis and eczema.

Results

A total of 2380 adolescents aged between 13 and 14 years were evaluated. The prevalence of doctor diagnosis for asthma, rhinitis and eczema was 3.4%, 8.5% and 2.2%, respectively. Compared with ISAAC results, we found a lower prevalence of wheeze and eczema symptoms: wheeze ever (37.6% vs 12.7%), recent wheeze (17.8% vs 6.5%), asthma ever (6.9% vs 4.6%), recent rush (22.4% vs 13.9%) and eczema ever (11.7% vs 3.6%). The prevalence of rhinitis symptoms in the GAN study was higher than the ISAAC results: nose symptoms in the past 12 months (36.6% vs 45.8%) and nose and eye symptoms in the past 12 months (23.1% vs 27.9). Significant associations were observed between symptoms of asthma–rhinitis–eczema and sex, race/ethnicity, smoking habit, physical exercise and sedentary activities.

Conclusions

In the last two decades, the prevalence of asthma and eczema symptoms in adolescent population in the city of Quito has significantly declined; however, the prevalence of rhinitis symptoms has increased. The reduction in asthma symptoms could be related to better managing the disease and changes in local environmental risk factors in the last years. Further studies must be conducted in the country to evaluate the change in trends in asthma and other related allergic diseases.

Gender differences in the perception of asthma respiratory symptoms in five Latin American countries

OBJECTIVES

To determine the differences between sexes in perceptions of asthma symptoms, asthma control, daily activities, and symptom exacerbation in Latin American countries.

METHODS

This cross-sectional study was performed using data from the Latin America Asthma Insight and Management (LA-AIM) study (n = 2167) carried out in Argentina, Brazil, Mexico, Venezuela, and Puerto Rico. Face-to-face interviews were conducted, and patients orally completed a 53-question survey assessing five main domains of asthma: symptoms, impact on daily activities, disease control, exacerbation, and treatment/medication.

RESULTS

Of the 2167 participants, 762 (35.2%) were males and 1405 (64.8%) were females. Male participants smoked more than females, but history of rhinitis and allergies was more common in females (p < 0.05). Women aged 18-40 years had a higher proportion of uncontrolled asthma compared to men of the same age (37.8% and 30.0%, respectively). A higher proportion of symptomatic females reported more frequent symptoms (daytime cough, shortness of breath, breathlessness/wheezing, sputum, tightness in the chest, etc.) than males (p < 0.05). Females also experienced more limitations in sports/recreational activities, normal physical exertion, social activities, sleep, and daily activities. Females consulted with health professionals more often than males (67.8% and 59.6%, respectively; p < 0.05). Asthma caused a feeling of lack of control over life in 42.6% of females and 31.4% of males.

CONCLUSION

In Latin America, females report more asthma symptoms, poorer asthma control, more impact on their daily activities, and more visits with health professionals than males.

Trends in hospital admissions and mortality rates for asthma in Ecuador: a joinpoint regression analysis of data from 2000 to 2018

BACKGROUND

Although asthma has emerged as an important public health problem over recent decades in Latin America, there are limited published data on national hospital admission and mortality rates for asthma from countries in the region.

OBJECTIVE

To analyse trends in asthma hospitalisation and mortality rates in Ecuador over a 19-year period from 2000 to 2018.

METHODS

Hospital discharge and death certificates listing asthma, as defined in the International Classification of Diseases 10th Revision codes (J45 and J46), were used to analyse time trends in rates of hospital admissions and mortality for asthma. The data were obtained from the Ecuadorian National Institute of Statistics and Census. Crude and age-standardised rates were estimated for the entire population. Additionally, specific rates by sex, age and region were estimated. We used joinpoint analysis to identify national trends.

RESULT

During 2000-2018, a total of 58 250 hospitalisations and 1328 deaths due to asthma were identified. The average annual rates for hospitalisation and mortality attributed to asthma were estimated to be 21 (95% CI 19.3 to 22.8) and 5.2 (95% CI 4.4 to 6.0) per 100 000 population, respectively, over this period. Asthma hospital admissions decreased from 28 to 13.7 per 100 000 population between 2000 and 2018, and asthma mortality decreased from 0.8 to 0.3 per 100 000 population over the same period. Based on jointpoint analysis, two temporal trends were identified for hospital admissions. Between 2000 and 2011, hospital admissions decreased 0.8% per year and between 2011 and 2018 decreased 6.6% per year (p<0.05). On average, hospitalisation rates decreased 3.1% per year (p<0.05) over the entire study period. Mortality rate decreased 5.6% per year (p<0.05) over the 19-year period. Hospitalisation rates were higher among females, those aged 5 to 19 years and those living in the Coast region.

CONCLUSIONS

Our analysis shows a temporal trend of reduction in rates of hospitalisations and deaths attributed to asthma between 2000 and 2018 in Ecuador, consistent with similar trends elsewhere in the Latin American region. Health registration systems in Latin America need to be improved to provide reliable data for future between and within country comparisons of trends in asthma hospitalisations and deaths.

A global analysis of the regional variation in the symptoms of acute respiratory infection during childhood: Epidemics and their association with environmental vulnerability

Using Demographic and Health Surveys from 48 low-income and middle-income countries (N = 432,860), we investigated whether or not the presence of symptoms of acute respiratory infection (ARI) are contingent on environmental vulnerabilities such as the region, the level of ambient air pollution, community orphanhood status, and household poverty among young children under five. In addition, we also examined whether such an effect may be a consequence of socioeconomic development and/or lifestyle. Using multilevel logistic regression models, environmental vulnerability was found to be significantly associated with the likelihood of childhood ARI symptoms and this association seemed to be related to the level of ambient air pollution. Our findings suggest that important roles are played by both geographic region and ambient air pollution, and that these factors may disproportionately shape a child's risk of ARI symptoms in a global context.

Exposure to environmental tobacco smoke and prevalence of asthma among adolescents in a middle eastern country

Background

There is increasing evidence linking environmental tobacco smoke (ETS) exposure at homes to the development of asthma among adolescents. Few studies have addressed this issue in the Middle Eastern countries including Kuwait. Therefore, this cross-sectional study assessed the prevalence of ETS exposure at home, prevalence of asthma and other respiratory conditions and examined the ETS exposure at home and personal tobacco smoking as risk factors for self-reported asthma among high-school students in Kuwait.

Methods

In this cross-sectional study, we enrolled participants from nine high-schools of Hawally Governorate of Kuwait during October 2015. We adapted a previously validated self-administered questionnaire for data collection. Prevalence of self-reported asthma and ETS exposure (≥ 1 smoker at home vs. none) were computed. The association between exposures of interest and self-reported asthma status was examined using a multivariable log-binomial regression model.

Results

Of 800 enrolled participants, 746 (92.2%) consented and completed the questionnaire. The participants with mean (SD) age of 16.8 (0.68) years were predominantly Kuwaiti (74.8%) and female (50.1%). The prevalence of ETS exposure at home and personal current smoking was 54 and 12.4% respectively. Self-reported asthma prevalence was 20.5%. Furthermore, the prevalence of physician-diagnosed asthma, wheezing during the last 12 months and wheezing ‘ever’ was 16.4, 20.1 and 26.2%, respectively. Fitted multivariable log-binomial regression model revealed that compared with the non-asthmatic, participants with self-reported asthma tended to be current smokers (adjusted prevalence ratio (adjusted PR) = 1.82; 95% CI: 1.30–2.56; p = 0.001) or have had ETS exposure at home (adjusted PR = 1.64; 95% CI: 1.21–2.23; p = 0.002).

Conclusions

We recorded a high prevalence of ETS exposure at home, high prevalence of self-reported asthma and identified ETS exposure at home and being a current smoker as strong risk factors for self-reported asthma among adolescents. Voluntary household smoking bans may substantially minimize the ETS exposure among adolescents. Additionally, such restriction may inculcate an antismoking attitude and prevent smoking initiation among adolescents. Such efforts may bring about reduction in ETS exposure and associated asthma risk and other smoking-related morbidities in this and other similar settings.

Understanding the dynamics of asthma symptoms between childhood and adolescence using latent transition analysis

OBJECTIVES

Asthma patterns in childhood are important predictors of unwanted outcomes in adolescence. We aimed to define asthma phenotypes in childhood and adolescence and evaluate the transitions between these phenotypes and factors potentially associated with the transitions.

METHODS

Baseline (1445 children), first round (1363 children/early adolescents) and second round (1206 adolescents) data from the SCAALA Project in Salvador, Brazil, were used. Phenotypes were defined by latent class analysis at three time points. Transitions between phenotypes were described and the effects of factors associated with transition probabilities estimated using latent transition analysis.

RESULTS

The "asymptomatic" and "symptomatic" phenotypes were identified. Approximately 5-6% of asymptomatic children in childhood/later childhood and early adolescence became symptomatic later in time. Maternal common mental disorders were identified as important risk factor for unhealthy states.

CONCLUSIONS

Asthma manifestations are characterized by frequent movements, especially between childhood and adolescence. Our study, by simultaneously defining disease subtypes, and examining the transitions and their potential predictors, highlights the importance of longitudinal studies to advance the understanding of the effects of social, environmental and biological mechanisms underlying asthma trajectories over time.

Impact of asthma control on different age groups in five Latin American countries

Background

Asthma is a chronic airway inflammatory condition of the airway and is classified as controlled, partially controlled, and uncontrolled. Patients with uncontrolled asthma are at greater risk for hospitalizations and visits to emergencies, and the condition has greater impact on their daily lives. The aim of this study was to evaluate asthma control, the use of health resources, and asthma's impact on the activities of daily living of patients with different age groups in 5 Latin American countries.

Methods

This was a retrospective analysis of The Latin America Asthma Insights and Management (LA AIM) study carried out in Argentina, Brazil, Mexico, Venezuela, and Puerto Rico. Asthmatics were splited into 3 age groups: 12–17, >17–40 and > 40 years old. An interview face to face was carried out and patients answered a questionnaire of 53 questions related to 5 main domains of asthma: symptoms, impact of asthma on daily living activities, patients' perceptions of asthma control, exacerbations, and treatment/medication.

Results

A total of 2167 asthmatics were interviewed. There was a low percentage of controlled patients (mean 9%) in all 3 groups with no particular difference among the five countries, but Venezuelan patients had a 71% chance of having uncontrolled asthma (p < 0.001).

Conclusion

In the 3 age groups, patients experienced poor asthma control, with no significant differences among the countries. Patients who used control medication had a greater chance of controlling their asthma, and those who had emergency health care visits had a greater chance of having uncontrolled asthma.

A systematic review of methodology used in the development of prediction models for future asthma exacerbation

Background

Clinical prediction models are widely used to guide medical advice and therapeutic interventions. Asthma is one of the most common chronic diseases globally and is characterised by acute deteriorations. These exacerbations are largely preventable, so there is interest in using clinical prediction models in this area. The objective of this review was to identify studies which have developed such models, determine whether consistent and appropriate methodology was used and whether statistically reliable prognostic models exist.

Methods

We searched online databases MEDLINE (1948 onwards), CINAHL Plus (1937 onwards), The Cochrane Library, Web of Science (1898 onwards) and ClinicalTrials.gov, using index terms relating to asthma and prognosis. Data was extracted and assessment of quality was based on GRADE and an early version of PROBAST (Prediction study Risk of Bias Assessment Tool). A meta-analysis of the discrimination and calibration measures was carried out to determine overall performance across models.

Results

Ten unique prognostic models were identified. GRADE identified moderate risk of bias in two of the studies, but more detailed quality assessment via PROBAST highlighted that most models were developed using highly selected and small datasets, incompletely recorded predictors and outcomes, and incomplete methodology. None of the identified models modelled recurrent exacerbations, instead favouring either presence/absence of an event, or time to first or specified event. Preferred methodologies were logistic regression and Cox proportional hazards regression.

The overall pooled c-statistic was 0.77 (95% confidence interval 0.73 to 0.80), though individually some models performed no better than chance. The meta-analysis had an I² value of 99.75% indicating a high amount of heterogeneity between studies. The majority of studies were small and did not include internal or external validation, therefore the individual performance measures are likely to be optimistic.

Conclusions

Current prognostic models for asthma exacerbations are heterogeneous in methodology, but reported c-statistics suggest a clinically useful model could be created. Studies were consistent in lacking robust validation and in not modelling serial events. Further research is required with respect to incorporating recurrent events, and to externally validate tools in large representative populations to demonstrate the generalizability of published results.

Mechanisms and Management of Asthma Exacerbations

Acute asthma remains an important medical emergency, the most frequent cause of acute admissions in children and a major source of morbidity for adults with asthma. In all ages with asthma, the presence of exacerbations is an important defining characteristic of asthma severity. In this review, we assess the epidemiology of acute asthma, the triggers of acute exacerbations, and the mechanisms that underlie these exacerbations. We also assess current treatments that prevent exacerbations, with an emphasis on the role of type 2 airway inflammation in the context of acute exacerbations and the novel treatments that effectively target this. Finally we review current management strategies of the exacerbations themselves.

Urbanisation and asthma in low-income and middle-income countries: a systematic review of the urban-rural differences in asthma prevalence

BACKGROUND

Urbanisation has been associated with temporal and geographical differences in asthma prevalence in low-income and middle-income countries (LMICs). However, little is known of the mechanisms by which urbanisation and asthma are associated, perhaps explained by the methodological approaches used to assess the urbanisation-asthma relationship.

OBJECTIVE

This review evaluated how epidemiological studies have assessed the relationship between asthma and urbanisation in LMICs, and explored urban/rural differences in asthma prevalence.

METHODS

Asthma studies comparing urban/rural areas, comparing cities and examining intraurban variation were assessed for eligibility. Included publications were evaluated for methodological quality and pooled OR were calculated to indicate the risk of asthma in urban over rural areas.

RESULTS

Seventy articles were included in our analysis. Sixty-three compared asthma prevalence between urban and rural areas, five compared asthma prevalence between cities and two examined intraurban variation in asthma prevalence. Urban residence was associated with a higher prevalence of asthma, regardless of asthma definition: current-wheeze OR:1.46 (95% CI:1.22 to 1.74), doctor diagnosis OR:1.89 (95% CI:1.47 to 2.41), wheeze-ever OR:1.44 (95% CI:1.15 to 1.81), self-reported asthma OR:1.77 (95% CI:1.33 to 2.35), asthma questionnaire OR:1.52 (95% CI:1.06 to 2.16) and exercise challenge OR:1.96 (95% CI:1.32 to 2.91).

CONCLUSIONS

Most evidence for the relationship between urbanisation and asthma in LMICs comes from studies comparing urban and rural areas. These studies tend to show a greater prevalence of asthma in urban compared to rural populations. However, these studies have been unable to identify which specific characteristics of the urbanisation process may be responsible. An approach to understand how different dimensions of urbanisation, using contextual household and individual indicators, is needed for a better understanding of how urbanisation affects asthma.

PROSPERO REGISTRATION NUMBER

CRD42017064470.

Genetic variants in 17q12-21 locus and childhood asthma in Brazil: Interaction with Varicella zoster virus seropositivity

BACKGROUND

Asthma is a complex disease with worldwide public health relevance, is related to environmental causes and a genetic predisposition. The chromosomal 17q12-21 locus has been consistently demonstrated to be associated with asthma risk. The effects of variants in the 17q12-21 locus on childhood asthma were first identified in a genome wide- association study. Since that time, those findings have been replicated in different populations but not in South American populations.

OBJECTIVE

This study aimed to investigate the role of variants in the 17q12-21 locus on asthma in a sample of Brazilian children.

METHODS

This was a cross-sectional study conducted on a cohort of 1247 children. These analyses used 50 Single Nucleotide Variants (SNVs) in the 17q12-21 locus were genotyped as part of a genome wide association study (GWAS).

RESULTS

Four SNVs (rs4065275, rs12603332, rs73985228 and rs77777702) were associated with childhood asthma. The rs73985228 exhibited the strongest association across the different genetic models (OR, 95%CI 2.8, 1.44-3.21, p < 0.01). In an analysis that was stratified by atopy, two SNVs (rs73985228 and rs2715555) were found to be associated with atopic and non-atopic asthma. For the first time, we observed a significant interaction with seropositivity for the Varicella zoster virus (for rs4065275, p = 0.02, and for rs12603332, p = 0.04); i.e., the association was found in those who were seropositive but not in those who were seronegative for this virus.

CONCLUSIONS

We confirmed the associations of variants in the 17q12-21 locus with atopic and non-atopic asthma and identified an interaction with seropositivity for the Varicella zoster virus.

Temporal evolution of and factors associated with asthma and wheezing in schoolchildren in Brazil

OBJECTIVE

To estimate the evolution of the prevalence of asthma and wheezing among schoolchildren in Brazil from 2012 to 2015, as well as to identify factors associated with both conditions.

METHODS

This was a cross-sectional study using data from the Brazilian National School-Based Adolescent Health Survey for 2012 and 2015. To characterize the evolution of the prevalence of asthma and wheezing, we used linear regression with weighted-least-squares estimation and presented the annual percent change (APC).

RESULTS

During the study period, there was a reduction in the prevalence of wheezing, from 23.2% in 2012 to 22.4% in 2015 (APC, -0.27). The prevalence of asthma increased from 12.4% in 2012 to 16.0% in 2015 (APC, 1.20). The increase in the prevalence of asthma was greatest in the southern region of the country (APC, 2.17). Having any history of smoking and having consumed alcohol in the last 30 days were factors that influenced the prevalence of wheezing and the prevalence of a self-reported diagnosis of asthma during the two years evaluated.

CONCLUSIONS

There has been an increase in the prevalence of asthma in recent years in Brazil. Our data underscore the importance of improving health strategies and policies aimed at the control of asthma.

Effect of Early-Life Geohelminth Infections on the Development of Wheezing at 5 Years of Age

RATIONALE

Exposures to geohelminths during gestation or early childhood may reduce risk of wheezing illness/asthma and atopy during childhood in tropical regions.

OBJECTIVES

To investigate the effect of maternal and early childhood geohelminths on development of wheeze/asthma and atopy during the first 5 years of life.

METHODS

A cohort of 2,404 neonates was followed to 5 years of age in a rural district in coastal Ecuador. Data on wheeze were collected by questionnaire and atopy was measured by allergen skin prick test reactivity to 10 allergens at 5 years. Stool samples from mothers and children were examined for geohelminths by microscopy.

MEASUREMENTS AND MAIN RESULTS

A total of 2,090 (86.9%) children were evaluated at 5 years. Geohelminths were observed in 45.5% of mothers and in 34.1% of children by 3 years. Wheeze and asthma were reported for 12.6% and 5.7% of children, respectively, whereas 14.0% had skin test reactivity at 5 years. Maternal geohelminths were associated with an increased risk of wheeze (adjusted odds ratio, 1.41; 95% confidence interval, 1.06-1.88), whereas childhood geohelminths over the first 3 years of life were associated with reduced risk of wheeze (adjusted odds ratio, 0.70; 95% confidence interval, 0.52-0.96) and asthma (adjusted odds ratio, 0.60; 95% confidence interval, 0.38-0.94) but not skin prick test reactivity. The effects on wheeze/asthma were greatest with later age of first infection, were observed only in skin test-negative children, but were not associated with parasite burden or specific geohelminths.

CONCLUSIONS

Although maternal exposures to geohelminths may increase childhood wheeze, childhood geohelminths during the first 3 years may provide protection through a nonallergic mechanism. Registered as an observational study (ISRCTN41239086).

Key factors associated with uncontrolled asthma - the Asthma Control in Latin America Study

Objective: This study aimed to estimate asthma control at specialist treatment centers in four Latin American countries and assess factors influencing poor asthma control.Methods: Patients aged ≥12 years with an asthma diagnosis and asthma medication prescription, followed at outpatient specialist centers in Argentina, Chile, Colombia, and Mexico, were included. The study received all applicable ethical approvals. The Asthma Control Test (ACT) was used to classify patients as having controlled (ACT 20-25) or uncontrolled (ACT ≤19) asthma. Frequency and statistical tests were used to assess the association between hospital admissions/exacerbations/emergency department (ED) visits and uncontrolled asthma; multivariate logistic regression was used to assess the association of uncontrolled asthma with clinical/demographic variables.Results: A total of 594 patients were included. Overall controlled-asthma prevalence was 43.4% (95% confidence interval [CI]: 39.0, 47.4). Patients with uncontrolled asthma were more likely to be women (adjusted odds ratio [aOR]: 1.85; p = 0.003), non-white (aOR: 2.14; p < 0.001), obese (aOR: 1.71; p = 0.036), to have a low monthly family income (aOR: 1.75; p = 0.004), to have severe asthma (aOR:1.59; p = 0.26), and, compared with patients with controlled asthma, to have a higher likelihood of asthma exacerbations (34.5% vs. 15.9%; p < 0.001), hospital admissions (6.9% vs. 3.1%; p = 0.042), and ED visits (34.5% vs. 15.9%; p < 0.001) due to asthma.Conclusions: Even in specialist ambulatory services, fewer than half of patients were classified as having controlled asthma. The proportion of uncontrolled patients varied according to clinical and demographic variables.

Parasites and allergy: Observations from Brazil

Brazil is a middle-income country undergoing the epidemiological transition. Effects of changes in daily life habits and access to clean water, sanitation and urban services on a growing urban population have contributed to a double burden of both infectious and noncommunicable chronic diseases. Studies have indicated that parasite infections may modulate the human immune system and influence the development of allergic conditions such as asthma. However, there is no consensus in the published literature on the effects of parasitic infections on allergy, perhaps as a consequence of factors determining the epidemiology of these infections that vary between populations such as age of first infection, duration and chronicity of infections, parasite burden and species, and host genetic susceptibility. In this review, we discuss the observations from Brazil concerning the relationship between parasite infections and allergy.

Multiobjective grammar-based genetic programming applied to the study of asthma and allergy epidemiology

Background

Asthma and allergies prevalence increased in recent decades, being a serious global health problem. They are complex diseases with strong contextual influence, so that the use of advanced machine learning tools such as genetic programming could be important for the understanding the causal mechanisms explaining those conditions. Here, we applied a multiobjective grammar-based genetic programming (MGGP) to a dataset composed by 1047 subjects. The dataset contains information on the environmental, psychosocial, socioeconomics, nutritional and infectious factors collected from participating children. The objective of this work is to generate models that explain the occurrence of asthma, and two markers of allergy: presence of IgE antibody against common allergens, and skin prick test positivity for common allergens (SPT).

Results

The average of the accuracies of the models for asthma higher in MGGP than C4.5. IgE were higher in MGGP than in both, logistic regression and C4.5. MGGP had levels of accuracy similar to RF, but unlike RF, MGGP was able to generate models that were easy to interpret.

Conclusions

MGGP has shown that infections, psychosocial, nutritional, hygiene, and socioeconomic factors may be related in such an intricate way, that could be hardly detected using traditional regression based epidemiological techniques. The algorithm MGGP was implemented in c ++ and is available on repository: http://bitbucket.org/ciml-ufjf/ciml-lib.

Electronic supplementary material

The online version of this article (10.1186/s12859-018-2233-z) contains supplementary material, which is available to authorized users.

Associations between infant fungal and bacterial dysbiosis and childhood atopic wheeze in a nonindustrialized setting

BACKGROUND

Asthma is the most prevalent chronic disease of childhood. Recently, we identified a critical window early in the life of both mice and Canadian infants during which gut microbial changes (dysbiosis) affect asthma development. Given geographic differences in human gut microbiota worldwide, we studied the effects of gut microbial dysbiosis on atopic wheeze in a population living in a distinct developing world environment.

OBJECTIVE

We sought to determine whether microbial alterations in early infancy are associated with the development of atopic wheeze in a nonindustrialized setting.

METHODS

We conducted a case-control study nested within a birth cohort from rural Ecuador in which we identified 27 children with atopic wheeze and 70 healthy control subjects at 5 years of age. We analyzed bacterial and eukaryotic gut microbiota in stool samples collected at 3 months of age using 16S and 18S sequencing. Bacterial metagenomes were predicted from 16S rRNA data by using Phylogenetic Investigation of Communities by Reconstruction of Unobserved States and categorized by function with Kyoto Encyclopedia of Genes and Genomes ontology. Concentrations of fecal short-chain fatty acids were determined by using gas chromatography.

RESULTS

As previously observed in Canadian infants, microbial dysbiosis at 3 months of age was associated with later development of atopic wheeze. However, the dysbiosis in Ecuadorian babies involved different bacterial taxa, was more pronounced, and also involved several fungal taxa. Predicted metagenomic analysis emphasized significant dysbiosis-associated differences in genes involved in carbohydrate and taurine metabolism. Levels of the fecal short-chain fatty acids acetate and caproate were reduced and increased, respectively, in the 3-month stool samples of children who went on to have atopic wheeze.

CONCLUSIONS

Our findings support the importance of fungal and bacterial microbiota during the first 100 days of life on the development of atopic wheeze and provide additional support for considering modulation of the gut microbiome as a primary asthma prevention strategy.

Hygiene Hypothesis in Asthma Development: Is Hygiene to Blame?

Industrialized countries have registered epidemic rates on allergic diseases, such as hay fever, asthma, eczema, and food allergies. The Hygiene Hypothesis was born from work made by Dr. David Strachan, who observed that younger siblings were less susceptible to eczema and asthma, and proposed that this was a result of increased transmission of infectious agents via unhygienic practices within a household. This initial hypothesis was then reframed as the old friends/microbiota hypothesis, implicating non-pathogenic commensal microorganisms as the source of immunomodulatory signals necessary to prevent immune-mediated chronic disorders. Although the hygiene hypothesis is supported by epidemiological research of allergic diseases in certain industrialized settings, it often fails to explain the incidence of asthma in less affluent regions of the world. In this review, we summarize up-to-date information on genetic and environmental factors associated with asthma in different human populations, and present evidence that calls for caution when associating hygiene with the pathogenesis of asthma and other allergic conditions.

Symptoms of asthma and associated factors in adolescents from Salvador, Bahia

OBJECTIVE

Identify the factors associated with asthma symptoms in adolescents.

METHODS

Cross-sectional study with the participation of 1,176 students between the ages of 11 and 17 years old, in Salvador, Bahia, Brazil. The asthma symptoms were identified by using the standardized questionnaire from The International Study of Asthma and Allergies in Childhood Program (ISAAC), phase III. The subjects' food intake data were collected by a semiquantitative food frequency questionnaire (FFQ) comprised of 97 food items. All of the information was collected during a single interview. Anthropometric, socioeconomic, and demographic data were collected from the study population. The robust Poisson model was adopted to obtain the raw and adjusted PR (prevalence ratio).

RESULTS

From the total number of adolescents, 57.6% are female and 83.71% of them were between 13 and 17 years old. The prevalence of asthma symptoms was of 7.6%, being higher among males (9.62%). The prevalence of wheezing in the last 12 months was 8.6%. Among the adolescents with rhinitis and eczema, the prevalence of asthma symptoms was of 15.2 and 14.3%, respectively. After an adjusted analysis, the following factors were identified: females PR = 0.64 (95%CI 0.42 - 0.96), rhinitis PR = 3.23 (95%CI 2.17 - 4.83) and the 2nd tertile of the healthy pattern (moderate consumption) PR = 0.61 (95%CI 0.37 - 0.99).

CONCLUSION

Rhinitis and eczema were presented as risk factors for asthma symptoms. The healthy food intake pattern that had been stratified in tertiles, presented the 2nd tertile as a protector for asthma symptoms.

Prevalence of asthma medical diagnosis among Brazilian adults: National Health Survey, 2013

OBJECTIVE

To estimate the prevalence of asthma medical diagnosis among the adult Brazilian population (aged ≥ 18 years).

METHODS

This is a cross-sectional, population-based study from the 2013 National Health Survey (NHS); it is a sampling cluster process with three stages of selection: census tracts, households, and individuals. The prevalence and 95% confidence interval for the outcome "asthma medical diagnosis" reported by the interviewed subjects were calculated, besides its distribution according to demographic and socioeconomic variables, macroregions, and urban or rural area of the country. Management of the disease was also evaluated among those who reported asthma medical diagnosis and the analyses were weighted.

RESULTS

A total of 60,202 adults were interviewed. The prevalence of asthma medical diagnosis was 4.4% (95%CI 4.1 - 4.7), and it was higher among the female subjects, the white skin-colored subjects, those with higher educational level, and those who lived in the south of Brazil. Among those who reported asthma medical diagnosis, a high percentage of asthma attacks were seen in the last 12 months, with around 80% using medication and about 15% referring severe limitation to their daily activities.

CONCLUSIONS

Although it seems there is asthma diagnosis stability in the country when compared with other researches, we still need public policies for improving the disease management.

Diet and Respiratory Health in Children from 11 Latin American Countries: Evidence from ISAAC Phase III

Background and Aim

The burden of childhood asthma and its risk factors is an important but neglected public health challenge in Latin America. We investigated the association between allergic symptoms and dietary intake in children from this region.

Methods

As part of the International Study of Asthma and Allergies in Childhood (ISAAC) Phase III, questionnaire collected dietary intake was investigated in relation to risk of parental/child reported current wheeze (primary outcome) and rhino-conjunctivitis and eczema. Per-country adjusted logistic regressions were performed, and combined effect sizes were calculated with meta-analyses.

Results

143,967 children from 11 countries had complete data. In children aged 6–7 years, current wheeze was negatively associated with higher fruit intake (adjusted odds ratio [aOR] 0.65; 95% CI 0.74, 0.97). Current rhino-conjunctivitis and eczema were statistically negatively associated with fruit intake (aOR 0.72; 95% CI 0.64, 0.82; and OR 0.64, 95% CI 0.56, 0.74, respectively). Vegetable intake was negatively associated with risk of symptoms in younger children, but these associations were attenuated in the 13–14 years old group. Fastfood/burger intake was positively associated with all three outcomes in the older children.

Conclusion

A higher intake of fruits and vegetables was associated with a lower prevalence of allergic symptoms in Latin American children. Conversely, intake of fastfood was positively associated with a higher prevalence of wheeze in adolescents. Improved dietary habits in children might help reduce the epidemic of allergic symptoms in Latin America. Food interventions in asthmatic children are needed to evaluate the possible public health impact of a better diet on respiratory health.

Electronic supplementary material

The online version of this article (doi:10.1007/s00408-017-0044-z) contains supplementary material, which is available to authorized users.

Rural to urban migration is associated with increased prevalence of childhood wheeze in a Latin-American city

Introduction

The urbanisation process has been associated with increases in asthma prevalence in urban and rural areas of low-income and middle-income countries (LMICs). However, although rural to urban migration and migration between cities are considered important determinants of this process, few studies have evaluated the effects of internal migration on asthma in urban populations of LMICs. The present study evaluated the effects of internal migration on the prevalence of wheeze in an urban area of Latin America.

Methods

We did a cross-sectional analysis of 2510 schoolchildren living in the city of Esmeraldas, Ecuador. Logistic regression was used to analyse associations between childhood wheeze and different aspects of migration among schoolchildren.

Results

31% of schoolchildren were migrants. Rural to urban migrants had a higher prevalence of wheeze, (adj.OR=2.01,95% CI1.30 to 3.01, p=0.001) compared with non-migrants. Age of migration and time since migration were associated with wheeze only for rural to urban migrants but not for urban to urban migrants. Children who had migrated after 3 years of age had a greater risk of wheeze (OR 2.51, 95% CI 1.56 to 3.97, p=0.001) than non-migrants while migrants with less than 5 years living in the new residence had a higher prevalence of wheeze than non-migrants (<3 years: OR=2.34, 95% CI 1.26 to 4.33, p<0.007 and 3–5 years: OR=3.03, 95% CI 1.49 to 6.15, p<0.002).

Conclusions

Our study provides evidence that rural to urban migration is associated with an increase in the prevalence of wheeze among schoolchildren living in a Latin-American city. Age of migration and time since migration were important determinants of wheeze only among migrants from rural areas. A better understanding of the social and environmental effects of internal migration could improve our understanding of the causes of the increase in asthma and differences in prevalence between urban and rural populations.

Relación de los mecanismos inmunológicos del asma y la contaminación ambiental

Introducción. Se calcula que más de 300 millones de personas alrededor del mundo padecen asma y se estima que para el año 2025 esta cifra se incremente a 400 millones debido a los contaminantes criterio. Sin embargo, dadas sus limitaciones, los estudios epidemiológicos son controversiales sobre la contaminación y el desarrollo de asma.Objetivos. Describir las diferencias y similitudes de la respuesta inmunológica de pacientes asmáticos y los modelos animales de asma alérgica después de la exposición a contaminantes criterio y elementos biológicos, para así identificar los factores inmunológicos relacionados con el desarrollo de asma.Materiales y método. Se realizó una búsqueda sistemática en las bases de datos sobre asma y los diferentes contaminantes criterio.Resultados. La respuesta Th2 es activada por la inhalación de ozono, dióxido de nitrógeno, azufre y la exposición aguda a material particulado, mientras que el contacto con ciertos tipos de pólenes y glucanos y la exposición crónica de partículas incrementa la respuesta Th1, la cual inhibe a la respuesta Th2 produciendo un “efecto protector”.Conclusiones. La respuesta Th1 podría causar baja o nula asociación entre la exposición a contaminación y el desarrollo de asma en las diferentes ciudades, adicionando de esta manera otra limitación a los estudios epidemiológicos.

Effect of polymorphisms on TGFB1 on allergic asthma and helminth infection in an African admixed population

BACKGROUND

Allergic asthma is a complex disorder that results from a combination of genetic and environmental factors. Studies suggest that helminth infections can activate a regulatory network characterized by the production of regulatory cytokines, such as interleukin 10 and transforming growth factor β1 (TGF-β1) and subsequently protect against immune-mediated diseases, such as asthma. On the other hand, TGF-β1 is increased in the lungs of individuals with asthma and may modulate airway inflammation. The role of TGF- β 1 single-nucleotide polymorphisms (SNPs) in allergic disease remains inconclusive.

OBJECTIVE

To evaluate the effects of genetic variations in the TGF-β1 on allergy and helminths infections in children.

METHODS

We tested for association among 4 TGF-β1 SNPs and allergic asthma, specific IgE, skin prick test result, and IL-10 production in 1,335 Brazilians. In addition, we analyzed the association with markers of helminth infection (parasite burden, anti-Ascaris IgE, and worm specific IgG4). The polymorphisms were genotyped using Taq Man probes.

RESULTS

We found an association between rs1800470 (C allele) and atopic wheezing (odds ratio [OR], 0.60; 95% confidence interval [CI], 0.37-0.95) and markers of allergy (OR, 0.41; 95% CI, 0.22-0.79). In contrast, a positive association was observed between the haplotype ACCA and Trichuris trichiura infection (OR, 1.85; P = .003) and Ascaris lumbricoides infection (OR, 2.01; P < .001). This haplotype was also associated with increased IL-10 production (β = 50.7; P < .001).

CONCLUSION

Individuals with TGF-β1 polymorphisms have an increased susceptibility to helminth infections and a lower risk of developing allergy. These studies suggest that immune modulation of allergic disease results not only from environmental factors but also from genetic susceptibility and IL-10 production.

Suggestive association between variants in IL1RAPL and asthma symptoms in Latin American children

Several genome-wide association studies have been conducted to investigate the influence of genetic polymorphisms in the development of allergic diseases, but few of them have included the X chromosome. The aim of present study was to perform an X chromosome-wide association study (X-WAS) for asthma symptoms. The study included 1307 children of which 294 were asthma cases. DNA was genotyped using 2.5 HumanOmni Beadchip from Illumina. Statistical analyses were performed in PLINK 1.9, MACH 1.0 and Minimac2. The variant rs12007907 (g.29483892C>A) in IL1RAPL gene was suggestively associated with asthma symptoms in discovery set (odds ratio (OR)=0.49, 95% confidence interval (CI): 0.37-0.67; P=3.33 × 10^-6). This result was replicated in the ProAr cohort in men only (OR=0.45, 95% CI: 0.21-0.95; P=0.038). Furthermore, investigating the functional role of the rs12007907 on the production a Th2-type cytokine, IL-13, we found a negative association between the minor allele A with IL-13 production in the discovery set (P=0.044). Gene-based analysis revealed that NUDT10 was the most consistently associated with asthma symptoms in discovery sample. In conclusion, the rs12007907 variant in IL1RAPL gene was negatively associated with asthma and IL-13 production in our study and a sex-specific association was observed in one of the validation samples. It suggests an effect on asthma susceptibility and may explain differences in severe asthma frequency between women and men.

Socioeconomic and environmental determinants of adolescent asthma in urban Latin America: an ecological analysis

The prevalence of asthma is high in urban areas of many Latin-American countries where societies show high levels of inequality and different levels of development. This study aimed to examine the relationship between asthma symptoms prevalence in adolescents living in Latin American urban centers and socioeconomic and environmental determinants measured at the ecological level. Asthma prevalence symptoms were obtained from the International Study of Asthma and Allergies in Childhood (ISAAC) phase III. A hierarchical conceptual framework was defined and the explanatory variables were organized in three levels: distal, intermediate, proximal. Linear regression models weighed by sample size were undertaken between asthma prevalence and the selected variables. Asthma prevalence was positively associated with Gini index, water supply and homicide rate, and inversely associated with the Human Development Index, crowding and adequate sanitation. This study provides evidence of the potential influence of poverty and social inequalities on current wheezing in adolescents in a complex social context like Latin America.

Helminths are positively associated with atopy and wheeze in Ugandan fishing communities: results from a cross-sectional survey

Background

Parasitic helminths are potent immunomodulators and chronic infections may protect against allergy‐related disease and atopy. We conducted a cross‐sectional survey to test the hypothesis that in heavily helminth‐exposed fishing villages on Lake Victoria, Uganda, helminth infections would be inversely associated with allergy‐related conditions.

Methods

A household survey was conducted as baseline to an anthelminthic intervention trial. Outcomes were reported wheeze in last year, atopy assessed both by skin prick test (SPT) and by the measurement of allergen‐specific IgE to dust mites and cockroach in plasma. Helminth infections were ascertained by stool, urine and haemoparasitology. Associations were examined using multivariable regression.

Results

Two thousand three hundred and sixteen individuals were surveyed. Prevalence of reported wheeze was 2% in under‐fives and 5% in participants ≥5 years; 19% had a positive SPT; median Dermatophagoides‐specific IgE and cockroach‐specific IgE were 1440 and 220 ng/ml, respectively. S. mansoni, N. americanus, S. stercoralis, T. trichiura, M. perstans and A. lumbricoides prevalence was estimated as 51%, 22%, 12%, 10%, 2% and 1%, respectively. S. mansoni was positively associated with Dermatophagoides‐specific IgE [adjusted geometric mean ratio (aGMR) (95% confidence interval) 1.64 (1.23, 2.18)]; T. trichiura with SPT [adjusted odds ratio (aOR) 2.08 (1.38, 3.15)]; M. perstans with cockroach‐specific IgE [aGMR 2.37 (1.39, 4.06)], A. lumbricoides with wheeze in participants ≥5 years [aOR 6.36 (1.10, 36.63)] and with Dermatophagoides‐specific IgE [aGMR 2.34 (1.11, 4.95)]. No inverse associations were observed.

Conclusions

Contrary to our hypothesis, we found little evidence of an inverse relationship between helminths and allergy‐related outcomes, but strong evidence that individuals with certain helminths were more prone to atopy in this setting.

The effect of internalization and other psychologic factors on the remission and severity of wheeze in children

BACKGROUND

Asthma prevalence in Latin America is high and continues to increase. There is evidence that the psychologic characteristics of the child are associated with greater asthma morbidity. This study aimed to investigate the independent effect of internalizing/externalizing problems on two asthma/wheeze outcomes: (i) remission and (ii) progression to severity on Latin American children with mild asthma symptoms at baseline.

METHODS

This was a prospective study in a cohort of 371 asthmatic children living in a poor urban area in Salvador, Brazil. The psychologic characteristics of the child were assessed using the Child Behavior Checklist (CBCL), and wheezing was defined using the ISAAC questionnaire at the start and end of follow-up. A multiple logistic regression model with random effects was used to examine the association between the psychologic components and both outcomes.

RESULTS

Remission of symptoms of wheeze was observed among 229 (61.73%) children. Remission was 56% lower among children with internalizing problems (OR = 0.54, 95% CI 0.33-0.87, p = 0.01). In addition, we found that 19 (8.76%) of the children acquired severe symptoms during follow-up and there was strong evidence of the effect of internalizing problems in increasing the risk of progression to severe wheeze symptoms (OR = 4.03, 95% CI 1.39-11.70, p = 0.01).

CONCLUSIONS

Children with internalizing problems but not externalizing had less remission of wheezing, and a higher risk of acquiring severe symptoms. These results highlight the importance of psychologic care for children with asthma, to improve the prognosis of this condition.

ERICA: prevalence of asthma in Brazilian adolescents

OBJECTIVE To describe the prevalence of asthma and physician-diagnosed asthma in Brazilian adolescents. METHODS Cross-sectional, national, school-based study with adolescents from 12 to 17 years old, participants in the Study of Cardiovascular Risks in Adolescents (ERICA). The study stratified the sample by region and grouped according to schools and classes with representativeness to the set of cities with more than 100,000 inhabitants of the Country, macro-regions, capitals, and Federal District. A questionnaire collected data through a self-filled in method. We calculated the prevalences and their confidence intervals of 95% (95%CI) according to sex, age group, type of school and skin color. RESULTS Between 2013 and 2014, 74,589 adolescents were evaluated, 55.3% of the female sex. The total prevalence of active asthma was of 13.1% (95%CI 12.1-13.9), being higher in girls (14.8%; 95%CI 13.7-16.0) when compared to boys (11.2%; 95%CI 10.3-12.2) in all geographical strata examined. It was also higher between students of private schools (15.9%; 95%CI 14.2-17.7) when compared to public ones (12.4%; 95%CI 11.4-13.4). It was higher in the Southeast region (14.5%; 95%CI 12.9-16.1), and in the city of Sao Paulo (16.7%; 95%CI 14.7-18.7). The lowest prevalence was observed in North region (9.7%; 95%CI 9.7-10.5), and in Teresina (6.3%; 95%CI 4.9-7.7). The prevalence of physician-diagnosed asthma was of 8.7% (95%CI 8.2-9.1); higher in the North region (13.5%; 95%CI 12.7-14.2), and in Porto Alegre (19.8%; 95%CI 17.5-22.3). It was lower in the Midwest (6.9%; 95%CI 6.0-7.8), and in Cuiaba (4.8%; 95%CI 3.8-5.9). We found no significant difference in the expression of this rate between the sexes, as well as in other variables evaluated by the study. CONCLUSIONS The prevalence of asthma in Brazilian adolescents is high. Rates of active asthma and physician-diagnosed asthma vary widely in different regions and capitals evaluated by the ERICA. These results may assist in the preparation of preventive programs and policies on health and a better understanding of the factors associated with asthma in this age group.

Prenatal and postnatal stress and wheeze in Mexican children: Sex-specific differences

BACKGROUND

Increasing evidence links early-life exposure to psychosocial stress with adverse childhood respiratory outcomes. The influence of exposure timing has not been completely elucidated.

OBJECTIVE

To examine the association between prenatal and postnatal maternal stress and wheeze in 417 children enrolled in a prospective birth cohort in Mexico City.

METHODS

Maternal negative life event (NLE) scores were ascertained in the second or third trimester of pregnancy and at the 48-month postnatal visit. Children's respiratory outcomes, caregiver report of ever wheeze, and wheeze in the past 12 months were obtained from the International Study of Asthma and Allergies in Childhood survey administered at 48 months. Associations between prenatal and postnatal NLE scores and wheeze were analyzed using a modified Poisson regression approach adjusting for covariates.

RESULTS

In separate models, higher maternal psychosocial stress during pregnancy (relative risk [RR], 1.12; 95% CI, 1.00-1.26) and postnatally (RR, 1.21; 95% CI, 1.08-1.35) were associated with increased risk of wheeze in the past 12 months with an evident exposure-response relationship. There was a significant interaction between postnatal stress and sex in relation to current wheeze. In a sex-stratified model, the association between postnatal stress and risk of wheeze in the past 12 months was stronger in girls (RR, 1.35; 95% CI, 1.13-1.61) than in boys (RR, 1.11; 95% CI, 0.97-1.27) (P for interaction = .04).

CONCLUSION

Prenatal and postnatal stress in mothers was associated with wheeze in preschool-aged children, and the effect of postnatal stress was stronger in girls. Understanding the temporal- and sex-specific effects of stress may better inform prevention strategies.

A genome-wide association study of asthma symptoms in Latin American children

Background

Asthma is a chronic disease of the airways and, despite the advances in the knowledge of associated genetic regions in recent years, their mechanisms have yet to be explored. Several genome-wide association studies have been carried out in recent years, but none of these have involved Latin American populations with a high level of miscegenation, as is seen in the Brazilian population.

Methods

1246 children were recruited from a longitudinal cohort study in Salvador, Brazil. Asthma symptoms were identified in accordance with an International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire. Following quality control, 1 877 526 autosomal SNPs were tested for association with childhood asthma symptoms by logistic regression using an additive genetic model. We complemented the analysis with an estimate of the phenotypic variance explained by common genetic variants. Replications were investigated in independent Mexican and US Latino samples.

Results

Two chromosomal regions reached genome-wide significance level for childhood asthma symptoms: the 14q11 region flanking the DAD1 and OXA1L genes (rs1999071, MAF 0.32, OR 1.78, 95 % CI 1.45–2.18, p-value 2.83 × 10⁻⁸) and 15q22 region flanking the FOXB1 gene (rs10519031, MAF 0.04, OR 3.0, 95 % CI 2.02–4.49, p-value 6.68 × 10⁻⁸ and rs8029377, MAF 0.03, OR 2.49, 95 % CI 1.76–3.53, p-value 2.45 × 10⁻⁷). eQTL analysis suggests that rs1999071 regulates the expression of OXA1L gene. However, the original findings were not replicated in the Mexican or US Latino samples.

Conclusions

We conclude that the 14q11 and 15q22 regions may be associated with asthma symptoms in childhood.

Electronic supplementary material

The online version of this article (doi:10.1186/s12863-015-0296-7) contains supplementary material, which is available to authorized users.

The association of intrafamilial violence against children with symptoms of atopic and non-atopic asthma: A cross-sectional study in Salvador, Brazil

This study aims to describe the types of intrafamilial violence perpetrated against children according to living conditions, family factors, and child characteristics, and to identify the association between types of intrafamilial violence and asthma symptoms in atopic and non-atopic children. A cross-sectional study was carried out with 1,370 caregivers as part of the Social Changes, Asthma and Allergy in Latin America (SCAALA) study, conducted in 2006 in Brazil. The study population was selected by random sampling. The main outcome measures were atopic and non-atopic asthma. We investigate the association between intrafamilial violence and asthma symptoms in atopic and non-atopic children. A backward multivariate logistic polytomous regression was performed to verify the main association. Nonviolent discipline (NVD) and maltreatment nonviolent discipline (MNVD) were positively associated with non-atopic asthma symptoms (NVD: odds ratio (OR)=1.95/95% confidence interval (CI)=1.17-3.25; MNVD: OR=1.95/95% CI=1.19-3.20). However, for the most severe intrafamilial violence, this association was not found after control of potential confounders. This study demonstrates the effect of types of intrafamilial violence on non-atopic asthma. Intrafamilial violence against children represents one more component in the determination of non-atopic asthma in Latin America.

Effects of maternal geohelminth infections on allergy in early childhood

Background

Maternal geohelminth infections during pregnancy may protect against allergy development in childhood.

Objective

We sought to investigate the effect of maternal geohelminths on the development of eczema, wheeze, and atopy during the first 3 years of life.

Methods

A cohort of 2404 neonates was followed to 3 years of age in a rural district in coastal Ecuador. Data on wheeze and eczema were collected by means of questionnaire and physical examination at 13, 24, and 36 months of age. Atopy was measured based on skin prick test (SPT) reactivity to 9 allergens at 36 months. Maternal stool samples were examined for geohelminths by microscopy. Data on potential confounders was collected after birth by questionnaire.

Results

Geohelminths were observed in 45.9% of mothers. Eczema and wheeze were reported for 17.7% and 25.9%, respectively, of 2069 (86.1%) children with complete follow-up to 3 years, and allergen SPT reactivity to any allergen was present in 17.2% and to house dust mite in 8.7%. Maternal geohelminth infections were not significantly associated with eczema (adjusted odds ratio [OR], 1.26; 95% CI, 0.98-1.61), wheeze (adjusted OR, 1.02; 95% CI, 0.82-1.27), and SPT reactivity to any allergen (adjusted OR, 0.79; 95% CI, 0.61-1.01). In subgroup analyses maternal geohelminths were associated with a significantly reduced risk of SPT reactivity to mite and other perennial allergens, and maternal ascariasis was associated with an increased risk of eczema and reduced risk of SPT reactivity to all allergens.

Conclusion

Our data do not support a protective effect of maternal infections with geohelminth parasites during pregnancy against the development of eczema and wheeze in early childhood, although there was evidence in subgroup analyses for a reduction in SPT reactivity to house dust mites and perennial allergens.

Effects of environment on human cytokine responses during childhood in the tropics: role of urban versus rural residence

BACKGROUND

Environment may have a key role in the development of the immune system in childhood and environmental exposures associated with rural residence may explain the low prevalence of allergic and autoimmune diseases in the rural tropics. We investigated the effects of urban versus rural residence on the adaptive immune response in children living in urban and rural areas in a tropical region of Latin America.

METHODS

We recruited school children in either rural communities in the Province of Esmeraldas or in urban neighborhoods in the city of Esmeraldas, Ecuador. We collected data on environmental exposures by questionnaire and on intestinal parasites by examination of stool samples. Peripheral blood leukocytes (PBLs) in whole blood were stimulated with superantigen, parasite antigens and aeroallergens and IFN-γ, IL-5, IL-10, IL-13, and IL-17 were measured in supernatants.

RESULTS

We evaluated 440 school children; 210 living in rural communities and 230 in the city of Esmeraldas. Overall, urban children had greater access to piped water (urban 98.7 % vs. rural 1.9 %), were more likely to have a household bathroom (urban 97.4 % vs. rural 54.8 %), and were less likely to be infected with soil-transmitted helminth infections (urban 20.9 % vs. rural 73.5 %). Generally, detectable levels of cytokines were more frequent in blood from children living in urban than rural areas. Urban residence was associated with a significantly greater frequency of IL-10 production spontaneously (adjusted OR 2.56, 95 % CI 1.05-6.24) and on stimulation with Ascaris (adj. OR 2.5, 95 % CI 1.09-5.79) and house dust mite (adj. 2.24, 95 % CI 1.07-4.70) antigens. Analysis of effects of environmental exposures on SEB-induced IL-10 production within urban and rural populations showed that some environmental exposures indicative of poor hygiene (urban - higher birth order, A. lumbricoides infection; rural - no bathroom, more peri-domiciliary animals, and living in a wood/bamboo house) were associated with elevated IL-10.

CONCLUSIONS

In our study population, the immune response of children living in an urban environment was associated more frequently with the production of the immune regulatory cytokine, IL-10. Some factors related to poor hygiene and living conditions were associated with elevated IL-10 production within urban and rural populations.

Risk factors for acute asthma in tropical America: a case-control study in the City of Esmeraldas, Ecuador

BACKGROUND

Despite the high asthma rates described in Latin America, asthma risk factors in poor urban settings are not well established. We investigated risk factors for acute asthma among Ecuadorian children.

METHODS

A matched case-control study was carried out in a public hospital serving a coastal city. Children with acute asthma were age- and sex-matched to non-asthmatics. A questionnaire was administered, and blood, as well as stool, and nasopharyngeal swabs were collected.

RESULTS

Sixty cases and 119 controls aged 5-15 were evaluated. High proportions of cases were atopic with population-attributable fractions for atopy of 68.5% for sIgE and 57.2% for SPT. Acute asthma risk increased with greater titers of mite IgE (3.51-50 kU/l vs. <0.70kU/l - OR 4.56, 95% CI 1.48-14.06, p = 0.008; >50kU/l vs. <0.70kU/l - OR 41.98, 95% CI: 8.97-196.39, p < 0.001). Asthma risk was significantly independently associated with bronchiolitis (adj. OR: 38.9, 95% CI 3.26-465), parental educational level (adj. OR 1.26, 95% CI: 1.08-1.46), and presence of sIgE (adj. OR: 36.7, 95% CI: 4.00-337), while a reduced risk was associated with current contact with pets (adj. OR: 0.07, 95% CI: 0.01-0.56). Rhinovirus infection was more frequent in cases (cases 35.6% vs. controls 7.8%, p = 0.002). None of the cases were on maintenance therapy with inhaled corticosteroids and most relied on emergency department for control.

CONCLUSIONS

A high proportion of children presenting to a public hospital with acute asthma were allergic to mite, particularly at high IgE titer. Poor asthma control resulted in overuse of emergency care.

Association between allergic responses and Schistosoma mansoni infection in residents in a low-endemic setting in Brazil

INTRODUCTION

Schistosomiasis is endemic in 76 countries and territories. Several studies have found an inverse correlation between parasitic disease and the development of allergies. The purpose of the present study was to determine whether infection with Schistosoma mansoni in subjects with a low parasite load is protective against allergy. The final sample consisted of 39 S. mansoni-positive and 52 S. mansoni-negative residents of a small community in northeastern Brazil.

METHODS

All subjects were submitted to the Kato-Katz test, anti-S. mansoni IgG measurement, the prick test for aeroallergens, eosinophil counts and serum IgE measurement.

RESULTS

Subjects who reacted to one or more antigens in the prick test were considered allergic. Only 7 S. mansoni-positive subjects (17.9%) reacted to one or more antigens, whereas 20 S. mansoni-negative subjects (38.5%) tested positive for allergy.

CONCLUSIONS

Our findings suggest that, in areas of low endemicity, infection with S. mansoni significantly reduces the risk of the development of allergy in subjects with a low parasite load.

A Traditional Diet Is Associated with a Reduced Risk of Eczema and Wheeze in Colombian Children

Background: Diet might influence the risk of allergic diseases. Evidence from developing countries with high prevalence of childhood asthma is scant. Methods: Information on wheeze, rhinitis, and eczema was collected from 3209 children aged 6–7 years in 2005, who were taking part in the International Study on Asthma and Allergy in Children (ISAAC) in Colombia. Intake frequency of twelve food groups was assessed. Associations between each food group and current wheeze, rhino-conjunctivitis, and eczema were investigated with multiple logistic regressions, adjusting for potential confounders. Simes’ procedure was used to test for multiple comparisons. Results: 14.9% of children reported wheeze in the last 12 months, 16% rhino-conjunctivitis, and 22% eczema. Eczema was negatively associated with consumption of fresh fruits and pulses three or more times per week (adjusted Odds ratio (aOR): 0.64; 95% Confidence Interval (CI): 0.49 to 0.83; p value = 0.004; and aOR: 0.62, 95% CI: 0.47 to 0.80; p value < 0.001, respectively). Current wheeze was negatively associated with intake of potatoes (aOR: 0.44, 95% CI: 0.31 to 0.62, p value = 0.005), whilst this outcome was positively associated with consumption of fast food (aOR: 1.76, 95% CI: 1.32 to 2.35, p value = 0.001). These associations remained statistically significant after controlling for multiple comparisons. Conclusions: A traditional diet might have a protective effect against eczema and wheeze in Colombian children, whilst intake of fast foods increases this risk.

Asthma in Latin America

Consistent with the diversity of Latin America, there is profound variability in asthma burden among and within countries in this region. Regional variation in asthma prevalence is likely multifactorial and due to genetics, perinatal exposures, diet, obesity, tobacco use, indoor and outdoor pollutants, psychosocial stress and microbial or parasitic infections. Similarly, non-uniform progress in asthma management leads to regional variability in disease morbidity. Future studies of distinct asthma phenotypes should follow-up well-characterised Latin American subgroups and examine risk factors that are unique or common in Latin America (eg, stress and violence, parasitic infections and use of biomass fuels for cooking). Because most Latin American countries share the same barriers to asthma management, concerted and multifaceted public health and research efforts are needed, including approaches to curtail tobacco use, campaigns to improve asthma treatment, broadening access to care and clinical trials of non-pharmacological interventions (eg, replacing biomass fuels with gas or electric stoves).

The Lake Victoria Island Intervention Study on Worms and Allergy-related diseases (LaVIISWA): study protocol for a randomised controlled trial

Background

The Hygiene Hypothesis proposes that infection exposure protects against inflammatory conditions. Helminths possess allergen-like molecules and may specifically modulate allergy-related immunological pathways to inhibit responses which protect against them. Mass drug administration is recommended for helminth-endemic communities to control helminth-induced pathology, but may also result in increased rates of inflammation-mediated diseases in resource-poor settings. Immunological studies integrated with implementation of helminth control measures may elucidate how helminth elimination contributes to ongoing epidemics of inflammatory diseases. We present the design of the Lake Victoria Island Intervention Study on Worms and Allergy-related diseases (LaVIISWA), a cluster-randomised trial evaluating the risks and benefits of intensive versus standard anthelminthic treatment for allergy-related diseases and other health outcomes.

Methods/Design

The setting is comprised of island fishing communities in Mukono district, Uganda. Twenty-six communities have been randomised in a 1:1 ratio to receive standard or intensive anthelminthic intervention for a three-year period. Baseline characteristics were collected immediately prior to intervention rollout, commenced in February 2013. Primary outcomes are reported wheeze in the past 12 months and atopy (skin prick test response and allergen-specific immunoglobulin (asIg) E concentration). Secondary outcomes are visible flexural dermatitis, helminth infections, haemoglobin, growth parameters, hepatosplenomegaly, and responses to vaccine antigens. The trial provides a platform for in-depth analysis of clinical and immunological consequences of the contrasting interventions.

Discussion

The baseline survey has been completed successfully in a challenging environment. Baseline characteristics were balanced between trial arms. Prevalence of Schistosoma mansoni, hookworm, Strongyloides stercoralis and Trichuris trichiura was 52%, 23%, 13%, and 12%, respectively; 31% of Schistosoma mansoni infections were heavy (>400 eggs/gram). The prevalence of reported wheeze and positive skin prick test to any allergen was 5% and 20%, respectively. Respectively, 77% and 87% of participants had Dermatophagoides- and German cockroach-specific IgE above 0.35 kUA/L. These characteristics suggest that the LaVIISWA study will provide an excellent framework for investigating beneficial and detrimental effects of worms and their treatment, and the mechanisms of such effects.

Trial registration

This trial was registered with Current Controlled Trials (identifier: ISRCTN47196031) on 7 September 2012.

Electronic supplementary material

The online version of this article (doi:10.1186/s13063-015-0702-5) contains supplementary material, which is available to authorized users.

[Dietary pattern, asthma, and atopic and non-atopic wheezing in children and adolescents: SCAALA study, Salvador, Bahia State, Brazil]

A cross-sectional study was conducted on dietary patterns and their influence on the occurrence of wheezing and atopic and non-atopic asthma in a sample of 1,168 children and adolescents in Salvador, Bahia State, Brazil. Wheezing and asthma symptoms in the previous 12 months were obtained using the ISAAC questionnaire. The presence of aeroallergen-specific IgE was identified. A food frequency questionnaire was used to define dietary patterns. The study applied logistic regression and multinomial polytomous logistic regression. Fish consumption was associated with a 27% reduction in wheezing (95%CI: 0.56-0.94), 37% in asthma (95%CI: 0.47-0.83), 51% in non-atopic asthma (95%CI: 0.31-0.79), and 38% in non-atopic wheezing (95%CI: 0.46-0.83). The highest tertile of dietary patterns reduced wheezing by 27% (95%CI: 0.57-0.95), atopic wheezing by 46% (95%CI: 0.30-0.98), asthma by 36% (95%CI: 0.49-0.83), and atopic asthma by 50% (95%CI: 0.28-0.89). Fish consumption may thus have a protective effect against wheezing and non-atopic asthma and dietary pattern against atopic asthma and wheezing.