A rural environment does not protect against asthma or other allergic diseases amongst Mexican children

Perinatal Risk Factors for Asthma and Allergic Rhinitis in Children and Adolescents

OBJECTIVES

In this study, we evaluated the associations between birth-related exposures, postnatal factors, and the risk of allergic rhinitis and asthma in children and adolescents.

METHODS

We performed a comprehensive search of five literature databases up to May 2023. To quantify the associations of birth-related exposures (birth weight, delivery mode, prematurity, sex, maternal age, and parental allergy history) and postnatal factors (birth order, number of siblings, breastfeeding exclusivity, and breastfeeding duration) with allergic disease, we calculated pooled odds ratios and 95% confidence intervals. We conducted subgroup analyses for allergic disease type, birth order, number of siblings, and parental allergy history. The methodological quality of the identified studies was evaluated using the Newcastle-Ottawa Scale.

RESULTS

This meta-analysis included 31 studies, encompassing 218,899 patients in total. The birth-related exposures of low birth weight, maternal age, and prematurity (less than 37 weeks gestation) were not significantly associated with the risk of asthma or allergic rhinitis during childhood or adolescence. Male sex, family history of allergy, and cesarean delivery were linked to an elevated risk of asthma or allergic rhinitis. Among postnatal factors, exclusive breastfeeding, breastfeeding for longer than 6 months, second or later birth order, and having siblings exhibited protective effects against allergic diseases in offspring.

CONCLUSION

The risks of allergic rhinitis and asthma were elevated in male patients, those delivered by cesarean section, and those with a family history of allergy. Conversely, exclusive breastfeeding, breastfeeding for longer than 6 months, and having siblings corresponded to a reduced risk of respiratory allergic diseases.

Geographische Unterschiede zwischen städtischem und ländlichem Raum beim Risiko für atopische Dermatitis: Systematischer Review und Meta-Analyse

Die atopische Dermatitis ist die häufigste chronisch‐entzündliche Hauterkrankung im Kindesalter. Einige Studien kamen zu dem Ergebnis, das Risiko für diese Erkrankung sei im städtischen Raum höher als im ländlichen. Wir haben die verfügbaren Studien systematisch untersucht und eine Meta‐Analyse durchgeführt, um Unterschiede im Risiko für atopische Dermatitis zwischen städtischem und ländlichem Raum zu erkennen. Die Suche in den Datenbanken Embase und MEDLINE wurde am 19. April 2021 durchgeführt. Einschlusskriterium war das Stichwort “Beobachtungsstudie”. Wir haben außerdem Subgruppenanalysen bezüglich Patientenalter, Publikationsjahr und Land durchgeführt. Insgesamt wurden bei der Datenbanksuche 2115 Studien aufgefunden, von denen letztlich 43 Studien mit insgesamt 1 728 855 Patienten in die Meta‐Analyse eingeschlossen wurden. Ein Wohnsitz im städtischen Raum war mit einem erhöhten Risiko für atopische Dermatitis assoziiert; die Odds Ratio war 1,56 (95 %‐Konfidenzintervall 1,43–1,71). Dieses signifikant erhöhte Risiko war nur bei Kindern zu beobachten (Odds Ratio 1,55, 95 %‐Konfidenzintervall 1,39–1,73), nicht jedoch bei Erwachsenen. Hier betrug die Odds Ratio 1,29 (95 %‐Konfidenzintervall 0,99–1,67). Das Risiko für atopische Dermatitis ist in den letzten Jahrzehnten angestiegen, wobei das Risiko in Entwicklungsländern mit einer Odds Ratio von 1,95 höher liegt als in Industrieländern (Odds Ratio 1,35). Unsere Studie bestätigt die Assoziation zwischen atopischer Dermatitis und dem Wohnsitz im städtischen gegenüber dem ländlichen Raum.

Geographic differences in atopic dermatitis risk between urban and rural area: A systematic review and meta-analysis

Atopic dermatitis is the most common chronic inflammatory skin disease affecting children. Some studies have reported a higher risk of atopic dermatitis in urban areas than in rural areas. We systematically reviewed and carried out a meta-analysis to investigate the differences in the development of atopic dermatitis between urban and rural areas. The search was performed on April 19, 2021, using Embase and MEDLINE databases. Eligible for inclusion were observational studies. Subgroup analyses were performed for age, publication year, and country. We identified 2,115 studies, and 43 studies with 1,728,855 subjects were finally included. Urban residency was associated with an increased risk of atopic dermatitis, with an odds ratio of 1.56 (95% confidence interval, 1.43-1.71). A significantly increased risk was observed only in children, with an odds ratio of 1.55 (95% confidence interval, 1.39-1.73), but not in adults, with an odds ratio of 1.29 (95% confidence interval, 0.99-1.67). The risk has increased in recent decades, with a higher risk in developing countries (odds ratio, 1.95) compared to developed countries (odds ratio, 1.35). Our study provides evidence of an association between atopic dermatitis and urban compared to rural living.

Understanding and controlling asthma in Latin America: A review of recent research informed by the SCAALA programme

Asthma is an important health concern in Latin America (LA) where it is associated with variable prevalence and disease burden between countries. High prevalence and morbidity have been observed in some regions, particularly marginalized urban populations. Research over the past 10 years from LA has shown that childhood disease is primarily non-atopic. The attenuation of atopy may be explained by enhanced immune regulation induced by intense exposures to environmental factors such as childhood infections and poor environmental conditions of the urban poor. Non-atopic symptoms are associated with environmental and lifestyle factors including poor living conditions, respiratory infections, psychosocial stress, obesity, and a diet of highly processed foods. Ancestry (particularly African) and genetic factors increase asthma risk, and some of these factors may be specific to LA settings. Asthma in LA tends to be poorly controlled and depends on access to health care and medications. There is a need to improve management and access to medication through primary health care. Future research should consider the heterogeneity of asthma to identify relevant endotypes and underlying causes. The outcome of such research will need to focus on implementable strategies relevant to populations living in resource-poor settings where the disease burden is greatest.

Global Asthma Network Phase I study in Mexico: prevalence of asthma symptoms, risk factors and altitude associations-a cross-sectional study

Background

Global Asthma Network (GAN) was established in 2012 as a development to the International Study of Asthma and Allergies in Childhood to improve asthma care globally.

Objective

To survey asthma, allergic rhinitis and atopic dermatitis in primary and secondary school children and to investigate and evaluate its prevalence, severity, management and risk factors in Mexico.

Methods

GAN Phase I is a cross-sectional, multicentre survey carried out in 15 centres corresponding to 14 Mexican cities throughout 2016–2019 using the validated Spanish language version of the GAN Phase I questionnaires. The questionnaires were completed by parents of 6–7-year-old primary school pupils (school children) and by 13–14-year-old adolescents.

Results

A total of 35 780 school children and 41 399 adolescents participated. Wheezing ever prevalence was 26.2% (95% CI 25.8% to 26.7%) in school children and 23.9% (95% CI 23.4% to 24.3%) in adolescents. The corresponding frequencies for current wheeze were 10.2% (95% CI 9.9% to 10.5%) and 11.6% (95% CI 11.2% to 11.9%). In school children, the risk factors for current wheeze were rhinitis (OR 4.484; 95% CI 3.915% to 5.134%) and rash symptoms (OR 1.735; 95% CI 1.461% to 2.059%). For adolescents, rhinitis symptoms (OR 3.492; 95% CI 3.188% to 3.825%) and allergic rhinitis diagnosis (OR 2.144; 95% CI 1.787% to 2.572%) were the most significant. For both groups, there was a negative relation with centres’ sea level altitude higher than 1500 m above mean sea level (p<0.005).

Conclusions

The most important risk factors for asthma symptoms in both age groups were the presence of rhinitis and rash symptoms or diagnosis. On the other hand, sea level altitude higher than 1500 metres was a protective factor.

Effect of maternal sleep, physical activity and screen time during pregnancy on the risk of childhood respiratory allergies: a sex-specific study

BACKGROUND

Early life exposure in the uterus had a long-term effect on children's health. As the prevalence of allergies is increasing with a remarkable sex difference, very few studies have traced back to their early origins. We sought to investigate if maternal behavioral exposure, herein sleep, physical activity, and screen time during pregnancy is associated with childhood respiratory allergies. The sex difference would be examined.

METHODS

Six thousand two hundred thirty-six mother-child pairs from Shanghai Children Allergy Study (SCAS) were enrolled, The International Study of Asthma and Allergies in Childhood questionnaire was adopted to evaluate respiratory allergic diseases.

RESULTS

14.6, 16.2, and 21.0% of children had asthma, wheeze, and allergic rhinitis, respectively. Maternal short sleep duration, lack of physical activity, and too much screen exposure during pregnancy could increase the risk of childhood respiratory allergies, however, the significance was found only in males. Moreover, a dose-response trend was clearly shown, any two of the three combined could increase the risk (OR,1.921; 95% CI,1.217-3.033), and the coexistence of all three further amplified the risk (OR,2.412; 95% CI,1.489-3.906). The findings can be verified in allergen test subgroup and each single type of respiratory allergies in most cases.

CONCLUSIONS

Maternal unhealthy behaviors during pregnancy could increase the risk of childhood respiratory allergies with a dose-response pattern. Males were more susceptible to the association. The identification of modifiable maternal risk behaviors lies in the emphasis of intervention in early life to face up increasing childhood allergies.

Early exposure to cats, dogs and farm animals and the risk of childhood asthma and allergy

BACKGROUND

Synergistic role of exposure to cats, dogs, and farm animals during infancy on the risk of childhood asthma and allergy remains unknown.

OBJECTIVES

To investigate independent and synergistic associations between exposure to indoor pets and farm animals during infancy and the risk of asthma and allergy by age 5.

METHODS

We studied 3781 children participating in the Finnish Type 1 Diabetes Prediction and Prevention (DIPP) Nutrition Study. At age 5, a validated version of the International Study of Asthma and Allergies in Childhood questionnaire was administered to collect information on asthma and allergic disease, and exposure to indoor pets and farm animals during the first year of life. Allergen-specific IgE antibodies were analyzed from serum samples. Statistical analyses employed Cox proportional hazards and logistic regression.

RESULTS

Having a dog in the house was inversely associated with the risk of asthma (HR 0.60; 95% CI, 0.38-0.96), allergic rhinitis (OR 0.72; 95% CI, 0.53-0.97), and atopic sensitization (OR 0.77; 95% CI, 0.63-0.96). Having a cat was associated with a decreased risk of atopic eczema (OR 0.68; 95% CI, 0.51-0.92). Farm animals were neither independently nor in synergy with indoor pets associated with the outcomes.

CONCLUSION

Having a dog or cat in the house during the first year of life may protect against childhood asthma and allergy. We did not find a synergistic association between cat, dog, and farm animal exposure on the risk of childhood asthma and allergy. Future research should identify specific causative exposures conferred by indoor pets and whether they could be recommended for allergy prevention.

Asthma prevalence, but not allergic rhinitis nor atopic dermatitis, is associated to exposure to dogs in adolescents

BACKGROUND

Exposure to pets can be a predisposing factor in the development of certain diseases, including allergic diseases.

OBJECTIVE

We analyzed the role that exposure to indoor dogs and cats plays in the prevalence of allergic diseases.

METHODS

We examined the cross-sectional data of 1056 women and 936 men aged 15 to 18 years; these individuals were selected through stratified and cluster random sampling. We asked all participants about their exposure to indoor dogs and cats during the year that preceded our study. The prevalence of allergic diseases was determined through core questions taken from The International Study of Asthma and Allergies in Childhood questionnaire.

RESULTS

The prevalence was 12.7% (95% CI: 11.3%-14.2%) for asthma, 9.0% (95% CI: 7.8%-10.4%) for allergic rhinitis, and 5.2% (95% CI: 4.3%-6.2%) for atopic dermatitis. The multivariate analyses showed that exposure to indoor dogs, but not indoor cats, was associated with asthma prevalence (aOR 1.37; 95% CI: 1.03-1.83), as was male sex (aOR=1.42; 95% CI: 1.08-1.86), a personal history of allergic rhinitis (aOR=3.24; 95% CI: 2.25-4.66), and a maternal history of asthma (aOR=3.06; 95% CI: 1.89-4.98). The population attributable risk for exposure to indoor dogs was 18%. Notably, neither allergic rhinitis nor atopic dermatitis was found to be associated with dog or cat exposure (p> 0.05).

CONCLUSION

Exposure to dogs in late adolescence is a factor associated with asthma, although its contribution to the development of asthma should be investigated in new studies.

How does parental history of atopic disease predict the risk of atopic dermatitis in a child? A systematic review and meta-analysis

BACKGROUND

Parental history of atopic disease is a well-established risk factor for the development of atopic dermatitis (AD), but several aspects of this association remain unclear.

OBJECTIVE

We sought to determine the association of parental history of atopic disease with AD in offspring.

METHODS

We searched PubMed and EMBASE through June 2018 for relevant records and adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Pooled odds ratios (ORs) with 95% CI were calculated using random-effects models.

RESULTS

A total of 163 records covering 149 unique studies were included. Of these, 119 studies were included in the meta-analysis. Individuals with parental history of atopic disease had increased odds of AD (OR, 1.81; 95% CI, 1.65-1.99). Parental asthma (OR, 1.56; 95% CI, 1.18-2.05) and allergic rhinitis (OR, 1.68; 95% CI, 1.34-2.11) had a smaller effect than AD (OR, 3.30; 95% CI, 2.46-4.42). The effect of maternal and paternal history was comparable for all atopic diseases. An increase in odds was observed when comparing the effect of having 1 (OR, 1.30; 95% CI, 1.15-1.47) or 2 atopic parents (OR, 2.08; 95% CI, 1.83-2.36), as well as having a parent with 1 (OR, 1.49; 95% CI, 1.28-1.74) or more atopic diseases (OR, 2.32; 95% CI, 1.92-2.81).

CONCLUSIONS

This study provides evidence-based risk estimates that may guide physicians who counsel parents with a history of atopic disease about their children's risk of AD. This information is of particular importance for future efforts toward establishing prophylactic interventions for AD on a general population level.

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.

Environmental risk factors for asthma in 13-14 year old African children

Background Asthma prevalence in African children is high. Factors driving the prevalence or disease severity are poorly understood. This study aims to investigate environmental factors associated with asthma and severity in African children. Methods Population based cross-sectional study of children aged 13-14 years from 10 African centers who participated in ISAAC III. Self-reported environmental exposures included engaging in physical exercise, television watching, various biomass and ETS exposure, consumption of paracetamol, large family sizes and having pets in the home. Univariable and multivariable analyses were done adjusting for center variations. Prevalences, odds ratio and 95% confidence intervals (CI) were calculated. Results There were 258 267 children recruited among the 13-14-year-old participants. Of these, 28,391 respondents from 232 schools completed both the written questionnaire (WQ) and environmental questionnaire (EQ). The prevalence of asthma and severe asthma were 12.8% (CI 12.4-13.2), and 8.7% (CI 8.4-8.0) respectively. Factors strongly associated with asthma were maternal smoking (OR = 1.41; 95%CI: 1.23-1.64), open fire heating (OR = 1.28; 95%CI: 1.08-1.51) electric heating (OR = 1.13; 95%CI: 1.01-1.28), physical exercise (OR = 1.29; 95%CI: 1.11-1.50), monthly paracetamol use (OR 1.23; 95%CI 1.13-1.33), having an elder sibling (OR = 0.87; 95%CI 0.77-0.98). Factors associated with severe asthma were maternal smoking (OR = 1.61; 95%CI: 1.38-1.89), cat pet (OR = 1.14; 95%CI: 1.04-1.25), frequent physical exercise (OR = 1.42; 95%CI: 1.23-1.64) and monthly paracetamol use (OR = 1.20; 95%CI 1.07, 1.34). Conclusion Several environmental exposures were associated with asthma and severe disease.

Exposure to dogs but not cats is associated to a decrease in the prevalence in atopic dermatitis amongst school-children

INTRODUCTION

The association regarding the exposure to pets, especially cats and dogs, and the prevalence of allergic diseases is inconsistent.

OBJECTIVE

We analyzed the role played by early exposure to dogs or cats in the prevalence of allergic diseases amongst school-aged children.

METHOD

Through a cross-sectional study, we examined 756 children, aged 6-7; these candidates were selected through cluster sampling. We inquired about the exposure that these children had had to dogs and cats, and whether these pets spent most of their time indoors or outdoors during the first year of the child's life. In order to identify the prevalence of allergic diseases and their symptoms, each child's parent completed the International Study of Asthma and Allergies in Childhood questionnaire.

RESULTS

Exposure to outdoor dogs was associated to nocturnal coughing, odds ratio (OR) 0.64, with a confidence interval of 95% (95% CI) 0.43-0.95 and with atopic dermatitis (OR: 0.39; 95% CI: 0.20-0.76). Interestingly, exposure to outdoor cats was associated to nocturnal coughing (OR: 0.51; 95% CI: 0.32-0.83) and current rhinitis symptoms (OR: 0.59; 95% CI 0.36-0.97). After carrying out the multivariate analyses, only exposure to dogs, both indoor and outdoor, was significantly associated to a decrease in the prevalence of atopic dermatitis OR 0.40 (95% CI: 0.20-0.79) and OR 0.38 (95% CI: 0.18-0.83), respectively.

CONCLUSION

Our findings suggest that exposure to dogs, whether they be indoor or outdoor pets, is associated to a decreased prevalence in atopic dermatitis.