Systematic review: Exposure to pets and risk of asthma and asthma-like symptoms

Effects of COVID-19 pandemic-associated reduction in respiratory infections on infantile asthma development

Background

It is speculated that the coronavirus disease 2019 (COVID-19) pandemic-associated reduction in the prevalence of respiratory tract infections has influenced the incidence of asthma in young children.

Objectives

We investigated an association between the reduction in viral infections and the reduction in asthma in young children.

Methods

The subjects were infants born in the early stages of the COVID-19 pandemic in Japan, which began in February 2020. A questionnaire survey related to asthma and allergy was conducted at 18 months and 3 years of age. These results were compared to those of age-matched infants during the nonpandemic period.

Results

There were no epidemics of viral infectious diseases until the target child was 18 months old. At 18 months, the incidence of asthma/asthmatic bronchitis diagnosed by physicians in pandemic children was significantly lower than that in nonpandemic children. In 3-year-olds, no marked difference was observed between nonpandemic infants and pandemic children, except for an increase in respiratory syncytial virus infection in pandemic children. In a comparative study of the same children at ages 18 months and 3 years, an increased prevalence of asthma/asthmatic bronchitis was observed in pandemic children. Furthermore, the incidence of asthma after respiratory syncytial virus infection in pandemic infants was significantly lower than that in nonpandemic children.

Conclusion

The COVID-19 pandemic-associated reduction in respiratory tract infections may have reduced the incidence of asthma in early childhood, and respiratory syncytial virus infection after 18 months of age had little effect on the onset of asthma. These results indicate the importance of preventing respiratory tract infections in early infancy.

Association of longitudinal pet ownership with wheezing in 3-year-old children using the distributed lag model: the Japan Environment and Children's Study

BACKGROUND

Time-varying exposures like pet ownership pose challenges for identifying critical windows due to multicollinearity when modeled simultaneously. The Distributed Lag Model (DLM) estimates critical windows for time-varying exposures, which are mainly continuous variables. However, applying complex functions such as high-order splines and nonlinear functions within DLMs may not be suitable for situations with limited time points or binary exposure, such as in questionnaire surveys.

OBJECTIVES

(1) We examined the estimation performance of a simple DLM with fractional polynomial function for time-varying binary exposures through simulation experiments. (2) We evaluated the impact of pet ownership on childhood wheezing onset and estimate critical windows.

METHODS

(1) We compared logistic regression including time-varying exposure in separate models, in one model simultaneously, and using DLM. For evaluation, we employed bias, empirical standard error (EmpSE), and mean squared error (MSE). (2) The Japan Environment and Children's Study (JECS) is a prospective birth cohort study of approximately 100,000 parent-child pairs, registered across Japan from 2011 to 2014. We applied DLM to the JECS data up to age 3. The estimated odds ratios (OR) were considered to be within critical windows when they were significant at the 5% level.

RESULTS

(1) DLM and the separate model exhibited lower bias compared to the simultaneously model. Additionally, both DLM and the simultaneously model demonstrated lower EmpSEs than the separate model. In all scenarios, DLM had lower MSEs than the other methods. Specifically, where critical windows is clearly present and exposure correlation is high, DLM showed MSEs about 1/2 to 1/200 of those of other models. (2) Application of DLM to the JECS data showed that, unlike other models, a significant exposure effect was observed only between the ages of 0 and 6 months. During that periods, the highest ORs were 1.07 (95% confidence interval, 1.01 to 1.14) , observed between the ages of 2 and 5 months.

CONCLUSIONS

(1) A simple DLM improves the accuracy of exposure effect and critical windows estimation. (2) 0-6 months may be the critical windows for the effect of pet ownership on the wheezing onset at 3 years.

Indoor air pollution is associated with respiratory symptoms in children in urban Vietnam

Exposure to indoor air pollution (IAP) is a leading environmental risk for respiratory diseases. We investigated the relationship between respiratory symptoms and polluting indoor activities such as smoking, cooking and contact with pets among children in Ho Chi Minh City (HCMC), Vietnam. A cross-sectional survey applied a multistage sampling method in 24 randomly selected secondary schools across the city. Approximately 15,000 students completed self-administrated questionnaires on risk factors and respiratory health outcomes within the preceding 12 months. Data were analyzed using a multivariable logistic regression model with robust standard errors. Wheeze was the most common respiratory symptom (39.5 %) reported, followed by sneezing and runny nose (28.3 %). A small percentage of students self-reported asthma (8.6 %). Approximately 56 % of participants lived with family members who smoked. A positive association between exposure to indoor secondhand smoke and respiratory symptoms was observed, with adjusted odds ratios (aOR) of 1.41 (95 % CI: 1.25-1.60, p < 0.001) for wheezing and 1.64 (95 % CI: 1.43-1.87, p < 0.001) for sneezing and runny nose, respectively. Using an open stove fuelled by coal, wood, or kerosene for cooking was associated with wheeze (aOR: 1.36, CI 95 %: 1.10-1.68, p = 0.01) and sneezing and runny nose (aOR: 1.36, CI 95 %: 1.09-1.69, p = 0.01). In the present study, IAP was associated with adverse health outcomes, as evidenced by an increase in respiratory symptoms reported within the previous 12 months.

Association Between Pet Keeping and Current Asthma Among Adolescents Living in Yazd; Evidence from Global Asthma Network (GAN) 2020 Cross-sectional Study

BACKGROUND

The relationship between current pet keeping and allergic diseases, including bronchial asthma in adolescents, is controversial. This study was conducted to evaluate these associations among children aged 13-14 years in Yazd.

METHODS

This study is part of a multicenter cross-sectional study of the Global Asthma Network (GAN) in Yazd, Iran, in 2020, in which 5141adolescents enrolled. Information on respiratory symptoms and pet-keeping (dog/cat/birds) was obtained by a questionnaire derived from the GAN standard questionnaire.

RESULTS

Of 5141 participants who completed the study, 1800 (35%) children kept pets during the last year. Birds were the most common pet kept by adolescents (88%). Severe asthma was more common in bird and cat keepers (P=0.003 and P=0.034, respectively) than dog keepers. Furthermore, there was a statistically significant association between study-defined current asthma and cat keeping, but not bird or dog ownership (P=0.02). Moreover, we found that current any pet-keeping (birds, cats, dogs) was associated with a higher prevalence of asthma-related symptoms, including wheezing, night dry cough, and exercise-induced wheezing in the past year (P=0.002, P=0.000 and P=0.000 respectively).

CONCLUSION

Current any pet-keeping is associated with asthma-related symptoms. Additionally, cat keeping had a significant association with study-defined current asthma. The current keeping of birds, as the most common pet in our area, or cat keeping increases the risk of severe asthma in adolescents. Therefore, as an important health tip, this needs to be reminded to families by health care providers.

Bird ownership and pulmonary outcomes apart from hypersensitivity pneumonitis in European older adults

BACKGROUND

Exposure to birds has been linked with several lung pathologies and especially hypersensitivity pneumonitis, but discordant literature exist on the potential effects of this exposure on other respiratory pathologies.

AIM

This study aims to examine the associations between bird ownership and asthma, lung cancer, and chronic obstructive pulmonary disease (COPD) in older European adults.

METHODS

A total of 28,109 participants from the Survey of Health, Ageing, and Retirement in Europe were employed and analyzed with multivariate logistic regressions.

RESULTS

No association was found with asthma or lung cancer. Bird ownership increased the odds for COPD diagnosis (OR=1.30; 95 % CI: 1.12-1.51) and more so in males (OR=1.53; 95 % CI: 1.25-1.87) after adjustment for demographic, respiratory, lifestyle, and socioeconomic factors. Male bird owners who smoke had an even more increased risk compared to non-smokers, as did those who lived in multi-person households compared to those living alone.

CONCLUSION

Bird ownership may be positively associated with COPD in older European males.

Asthma prevalence based on the Baidu index and China's Health Statistical Yearbook from 2011 to 2020 in China

Background

Due to environmental pollution, changes in lifestyle, and advancements in diagnostic technology, the prevalence of asthma has been increasing over the years. Although China has made early efforts in asthma epidemiology and prevention, there is still a lack of unified and comprehensive epidemiological research within the country. The objective of the study is to determine the nationwide prevalence distribution of asthma using the Baidu Index and China's Health Statistical Yearbook.

Methods

Based on China's Health Statistical Yearbook, we analyzed the gender and age distribution of asthma in China from 2011 to 2020, as well as the length of hospitalization and associated costs. By utilizing the Baidu Index and setting the covering all 31 provinces and autonomous regions in China, we obtained the Baidu Index for the keyword 'asthma'. Heatmaps and growth ratios described the prevalence and growth of asthma in mainland China.

Results

The average expenditure for discharged asthma (standard deviation) patients was ¥5,870 (808). The average length of stay (standard deviation) was 7.9 (0.38) days. During the period of 2011 to 2020, hospitalization expenses for asthma increased while the length of hospital stay decreased. The proportion of discharged patients who were children under the age of 5 were 25.3% (2011), 19.4% (2012), 16% (2013), 17.9% (2014), 13.9% (2015), 11.3% (2016), 10.2% (2017), 9.4% (2018), 8.1% (2019), and 7.2% (2020), respectively. The prevalence of asthma among boys was higher than girls before the age of 14. In contrast, the proportion of women with asthma was larger than men after the age of 14. During the period from 2011 to 2020, the median [The first quartile (Q1)-the third quartile (Q3)] daily asthma Baidu index in Guangdong, Beijing, Jiangsu, Sichuan, and Zhejiang were 419 (279-476), 328 (258-376), 315 (227-365), 272 (166-313), and 312 (233-362) respectively. Coastal regions showed higher levels of attention toward asthma, indicating a higher incidence rate. Since 2014, there has been a rapid increase in the level of attention toward asthma, with the provinces of Qinghai, Sichuan, and Guangdong experiencing the fastest growth.

Conclusion

There are regional variations in the prevalence of asthma among different provinces in China, and the overall prevalence of asthma is increasing.

The Primary Prevention of Atopy: Does Early Exposure to Cats and Dogs Prevent the Development of Allergy and Asthma in Children? A Comprehensive Analysis of the Literature

The current literature shows mixed results relating to the significance of environmental exposure, such as owning a pet, and the development of atopy in children. Our review aimed to collect the most recent evidence on the association between early-life cat and dog ownership and the development of allergy and asthma. A comprehensive literature review was performed using PubMed and Scopus. The search included the main keywords of our PICO: (((early exposure) AND (children) AND (allergy)) OR (asthma)) AND (dog) OR (cat). Randomized controlled trials (RCTs), case-control studies, clinical trials, meta-analyses, and systematic reviews of children within the last five years (2018-2023) were searched and included. During the search process, 52 articles from PubMed and 43 from Scopus were found. A total of 17 articles were deemed to be suitable and included. Fairly consistent results regarding early exposure to pets, in particular dogs, and the prevention of food allergies have been described. Furthermore, there seems to be a protective effect against allergy and asthma in relation to the number of pets owned. The likelihood of a child developing allergy and asthma seems to be influenced by various factors, including the child's genetic background and early exposure to different environmental factors, including allergens that may interact with the gut microbiota and immune system.

Environmental exposures in early-life and general health in childhood

BACKGROUND

Early-life environmental exposures are suspected to be involved in the development of chronic diseases later in life. Most studies conducted so far considered single or few exposures and single-health parameter. Our study aimed to identify a childhood general health score and assess its association with a wide range of pre- and post-natal environmental exposures.

METHODS

The analysis is based on 870 children (6-12 years) from six European birth cohorts participating in the Human Early-Life Exposome project. A total of 53 prenatal and 105 childhood environmental factors were considered, including lifestyle, social, urban and chemical exposures. We built a general health score by averaging three sub-scores (cardiometabolic, respiratory/allergy and mental) built from 15 health parameters. By construct, a child with a low score has a low general health status. Penalized multivariable regression through Least Absolute Shrinkage and Selection Operator (LASSO) was fitted in order to identify exposures associated with the general health score.

FINDINGS

The results of LASSO show that a lower general health score was associated with maternal passive and active smoking during pregnancy and postnatal exposure to methylparaben, copper, indoor air pollutants, high intake of caffeinated drinks and few contacts with friends and family. Higher child's general health score was associated with prenatal exposure to a bluespace near residency and postnatal exposures to pets, cobalt, high intakes of vegetables and more physical activity. Against our hypotheses, postnatal exposure to organochlorine compounds and perfluorooctanoate were associated with a higher child's general health score.

CONCLUSION

By using a general health score summarizing the child cardiometabolic, respiratory/allergy and mental health, this study reinforced previously suspected environmental factors associated with various child health parameters (e.g. tobacco, air pollutants) and identified new factors (e.g. pets, bluespace) warranting further investigations.

[Are pets, dog or cat, a risk or a protector factor for the development or exacerbation of asthma? Systematic review of systematic reviews]

BACKGROUND

Preliminary studies have shown conflicting results on the association between exposure to pets (cat or dog) and asthma. Previous scientific evidence has not been clear to determine if avoiding or allowing the exposure to pets could prevent, improve, or worsen the development of asthma and its symptoms.

OBJECTIVE

To try to explain the controversial relationship between exposure to pets (dog or cat) and its effect on the development of asthma or the exacerbation of symptoms in both children and adults.

METHODS

A standardized search in five electronic databases by an independent reviewer was carried out. The final sample of studies included in the overview of systematic reviews was screened and synthesized through a master table. A narrative description of the results was made.

RESULTS

This systematic review of systematic found determined principally that having a cat could be a risk factor and having a dog a protective factor in the development of asthma. However, early exposure to both cats and dogs (before the age of two) reduces the probability of asthma symptoms and wheezing in the school years. Additionally, having antecedents of sensibilization to pets allergen could be a risk factor to exacerbate asthma in both children and adults.

Exposure to dogs and cats and risk of asthma: A retrospective study

Findings on the relationship between pet exposure and asthma in western countries are inconsistent. This retrospective study examined the association of owning a dog or cat with the onset of asthma in Japanese people. We also investigated whether there is a critical window during which exposure to dogs and cats can reduce the risk of asthma by stratifying the analysis by the age at which pet ownership began. We analyzed data collected in an internet survey conducted by the Japan Pet Food Association in 2021. Valid data were obtained from 4290 participants for analysis of dog ownership and 4308 participants for analysis of cat ownership. In these respective groups, 41.2% had owned a dog and 26.5% had owned a cat. During the follow-up period, 5.7% of dog owners and 14.8% of non-dog owners developed asthma, as did 5.6% of cat owners and 13.5% of non-cat owners. On binomial logistic regression analysis, participants who had not owned a dog had an odds ratio (OR) of 2.01 (95% confidence interval (CI): 1.45-2.78) of developing asthma compared to those who had owned a dog after adjustment for sociodemographic characteristics. The corresponding OR of asthma onset among participants who had not owned a cat was 2.24 (95%CI: 1.56-3.23). Stratified analysis showed that while younger participants who had not owned a dog had higher ORs of developing asthma, those who had not owned a cat had similar ORs of asthma onset across all age categories. These results suggest that while there may be a critical window in early life during which exposure to dogs can prevent asthma onset, the protective effect of cat exposure is constant across all ages in Japan.

Environmental Interventions for Asthma

Exposure and sensitization to environmental factors play a fundamental role in asthma development and is strongly associated with asthma morbidity. While hereditary factors are critical determinants of asthma, exposures to environmental factors are implicated in the phenotypic expression of asthma and have been strongly associated in the risk of its development. Significant interest has thus been geared toward potentially modifiable environmental exposures which may lead to the development of asthma. Allergen exposure, in particular indoor allergens, plays a significant role in the pathogenesis of asthma, and remediation is a primary component of asthma management. In the home, multifaceted and multitargeted environmental control strategies have been shown to reduce home exposures and improve asthma outcomes. In addition to the home environment, assessment of the school, daycare, and workplace environments of patients with asthma is necessary to ensure appropriate environmental control measures in conjunction with medical care. This article will discuss the role of the environment on asthma, review targeted environmental therapy, and examine environmental control measures to suppress environmental exposures in the home and school setting.

Trajectories of asthma symptom presenting as wheezing and their associations with family environmental factors among children in Australia: evidence from a national birth cohort study

OBJECTIVES

Asthma is one of the greatest health burdens, yet contributors to asthma symptom trajectories are understudied in Australian children. We aimed to assess the trajectories of asthma symptom and their associations with several family environmental factors during the childhood period in Australia.

DESIGN

Secondary analysis from a cross-sequential cohort study.

SETTING

Nationwide representative data from the 'Longitudinal Study of Australian Children (LSAC)'.

PARTICIPANTS

Participants from the LSAC birth cohort.

OUTCOME MEASURES

Asthma symptom trajectory groups.

METHODS

Asthma symptom presenting as wheezing, family environmental factors and sociodemographic data (2004-2018) were obtained from the LSAC. Group-based trajectory modelling was applied to identify asthma symptom trajectories and multivariable logistic regression models were used to assess the associations between these and environmental factors.

RESULTS

Of 5107 children in the LSAC cohort, 3846 were included in our final analysis. We identified three distinct asthma symptom trajectories from age 0/1 year to 14/15 years: 'low/no' (69%), 'transient high' (17%) and 'persistent high' (14%). Compared with the 'low/no' group, children exposed to 'moderate and declining' (relative risk ratio (RRR): 2.22, 95% CI 1.94 to 2.54; RRR: 1.26, 95% CI 1.08 to 1.46) and 'high and persistent' prevalence of maternal smoking (RRR: 1.41, 95% CI 1.23 to 1.60; RRR: 1.26, 95% CI 1.10 to 1.44) were at increased risk of being classified into the 'transient high' and 'persistent high' trajectories of asthma symptom. Persistently bad external dwelling conditions (RRR: 1.27, 95% CI 1.07 to 1.51) were associated with 'transient high' trajectory while 'moderate and increasing' conditions of cluttered homes (RRR: 1.37, 95% CI 1.20 to 1.56) were associated with 'persistent high' trajectory of asthma symptom. Exposure to tobacco smoke inside the house also increased the risk of being in the 'persistent high' trajectory group (RRR: 1.30, 95% CI 1.12 to 1.50).

CONCLUSION

Poor home environment increased the risk of asthma symptom during childhood. Improving home environment and reducing exposure to tobacco smoke may facilitate a favourable asthma symptom trajectory during childhood.

The role of environmental allergen control in the management of asthma

Allergen exposure may exacerbate asthma symptoms in sensitized patients. Allergen reduction or avoidance measures have been widely utilized; however, there is ongoing controversy on the effectiveness of specific allergen control measures in the management of children with asthma. Often, allergen avoidance strategies are not recommended by guidelines because they can be complex or burdensome, although individual patients may benefit. Here we explore the potential for intervention against exposure to the major allergens implicated in asthma (ie, house dust mites, indoor molds, rodents, cockroaches, furry pets, and outdoor molds and pollens), and subsequent effects on asthma symptoms. We critically assess the available evidence regarding the clinical benefits of specific environmental control measures for each allergen. Finally, we underscore the need for standardized and multifaceted approaches in research and real-life settings, which would result in the identification of more personalized and beneficial prevention strategies.

Associations of early-life pet ownership with asthma and allergic sensitization: a meta-analysis of >77,000 children from the EU Child Cohort Network

BACKGROUND

Studies examining associations of early-life cat and dog ownership with childhood asthma have reported inconsistent results. Several factors could explain these inconsistencies, including type of pet, timing and degree of exposure.

OBJECTIVE

To study associations of early-life cat and dog ownership with school-age asthma, including the role of type (cat versus dog), timing (never, prenatal or early childhood) and degree (number) of ownership, and the role of allergic sensitisation.

METHODS

We used harmonised data from 77,434 mother-child dyads aged 5-11 years from nine birth cohorts in the EU Child Cohort Network. Associations were examined through the DataSHIELD platform using adjusted logistic regression models, fitted separately for each cohort and combined using random-effects meta-analysis.

RESULTS

Early-life cat and dog ownership ranged between 12-45% and 7-47% respectively, and prevalence of asthma between 2-20%. There was no overall association between either cat or dog ownership and asthma (OR: 0.97 (95% CI: 0.87-1.09) and 0.92 (0.85-1.01), respectively). Timing and degree of ownership did not strongly influence associations. Cat and dog ownership were also not associated with cat- and dog-specific allergic sensitisation (OR: 0.92 (0.75-1.13) and 0.93 (0.57-1.54), respectively). However, cat- and dog-specific allergic sensitisation were strongly associated with school-age asthma (OR: 6.69 (4.91-9.10) and 5.98 (3.14-11.36), respectively). There was also some indication of an interaction between ownership and sensitisation, suggesting that ownership may exacerbate the risks associated with pet-specific sensitisation, but offer some protection against asthma in the absence of sensitisation.

CONCLUSION

Our findings do not support early-life cat and dog ownership in themselves increasing the risk of school-age asthma, but suggest that ownership may potentially exacerbate the risks associated with cat- and dog-specific allergic sensitisation.

Family, neighborhood and psychosocial environmental factors and their associations with asthma in Australia: a systematic review and Meta-analysis

OBJECTIVE

Various associations between different environmental exposures and asthma have been reported in different countries and populations. We aimed to investigate the associations between family, neighborhood and psychosocial environmental factors and asthma-symptoms in Australia by conducting a systematic review and meta-analysis.

DATA SOURCES

We analyzed the primary research studies conducted in Australia across multiple databases, including PubMed, EMBASE and Scopus, published between 2000 and 2020.

STUDY SELECTIONS

The reviews and analyses focused on the overall association of different environmental exposures with the exacerbation of asthma-symptoms or asthma-related hospital visits. Quality-effect meta-analysis was done to estimate the pooled odds ratio for different environmental exposures for asthma-symptoms.

RESULTS

Among the 4799 unique published articles found, 46 were included here for systematic review and 28 for meta-analysis. Our review found that psychosocial factors, including low socioeconomic condition, maternal depression, mental stress, ethnicity, and discrimination, are associated with asthma-symptoms. Pooled analysis was conducted on family and neighborhood environmental factors and revealed that environmental tobacco smoking (ETS) (OR 1·69, 95% CI 1·19-2·38), synthetic bedding (OR 1·91, 95% CI 1·48-2·47) and gas heaters (OR 1·40, 95% CI 1·12-1·76) had significant overall associations with asthma-symptoms in Australia.

CONCLUSION

Although the studies were heterogeneous, both systematic review and meta-analysis found several psychosocial and family environmental exposures significantly associated with asthma-symptoms. Further study to identify their causal relationship and modification may reduce asthma-symptoms in the Australian population.

[Cultivation and use of medicinal plants and association with reporting of childhood asthma: A case-control study in the Bogotá savanna]

Introduction

The prevalence of childhood asthma has increased in recent years. The World Health Organization has called for conducting research exploring the role of traditional medicine and medicinal plants in respiratory disease control.

Objective

To identify the relationship between the prevalence of childhood asthma and traditional care of the respiratory system, including cultivation and use of medicinal plants.

Methods

We conducted an observational, analytic, case-control study that included children 2 to 14 years old who used official health services in eight municipalities near Bogota between 2014 and 2015. Cases were children diagnosed with asthma. We randomly selected the controls among the remaining patients of the same healthcare facilities. We applied an 18-question survey. The Mantel-Haenszel procedure identified significant associations using 95% confidence intervals.

Results

We surveyed the caretakers of 97 cases and 279 controls in eight municipalities. Some 23.4% (88/376) and 37.9% (142/375) reported using traditional remedies for fever control and common cold management, respectively. 8.8% (33/376) reported following traditional care during a common cold, 30.4% (114/375) reported growing medicinal plants at home, and 45% (166/369) reported using medicinal plants for health purposes in their household. Multivariate analysis showed that having and using medicinal plants at home is associated with a lower reporting of asthma (odds ratio 0.49; 95% confidence interval: 0.25 to 0.99).

Conclusions

Cultivating and using medicinal plants at home is associated with a lower reporting of childhood asthma. Researchers should consider the therapeutic, environmental, and cultural properties of medicinal plants to prevent respiratory diseases.

Childhood Origins of Adult Lung Disease as Opportunities for Prevention

Prenatal and childhood exposures have been shown to impact lung development, lung function trajectory, and incidence and prevalence of respiratory disease. Early life may serve as a window of susceptibility to such exposures, with the potential to influence lifelong respiratory health. Risk factors encountered in early life with potentially durable impact on lung health include prematurity, respiratory viral illness, allergen sensitization and exposure, tobacco use and exposure, indoor and outdoor pollution, diet, and obesity. These exposures vary in the extent to which they are modifiable, and interventions aimed at reducing harmful exposures range from individual-level behavior modification to policy initiatives implemented to promote population health. For many exposures, including tobacco-related exposures, multilevel interventions are needed. Future research is needed to provide insight as to early-life interventions to promote optimal lung growth and prevent development of chronic respiratory disease. Clinicians should play an active role, assisting individual patients in avoiding known detrimental exposures including maternal smoking during pregnancy and initiation of active smoking. Clinicians can be empowered by evidence to support policies promoting reduction of population-level risk factors, such as restriction on electronic cigarette sales and legislation to uphold air quality standards, to encourage attainment of maximal lung function and reduce risk of chronic lung disease.

Decreasing ten-year (2008-2018) trends of the prevalence of childhood asthma and air pollution in Southern Taiwan

Background

Asthma is a common pediatric chronic respiratory disease worldwide. Previous studies showed the prevalence of childhood asthma increased in developed countries as well as in Taiwan in the late 20th century. Recently, several reports from different parts of the world showed a reversed trend in this epidemic of childhood asthma prevalence. This study investigated the trend of childhood asthma through serial cross-section questionnaire surveys in the southern part of Taiwan, and identified associated factors related to this trend in elementary school children.

Methods

We used the Chinese version of the International Study of Asthma and Allergies in Childhood (ISAAC)²⁹ questionnaire to assess the asthma status of elementary school students aged 6–12 years in Tainan city in 3 independent study periods, namely, 2008–2009, 2010–2012, and 2017–2018. We assessed the trend of “asthma” and “related respiratory symptoms” across 3 study periods.

Results

Of the 19,633 respondents, 17,545 (89.4%) completed the questionnaires. After adjustment for covariates, the prevalence of asthma and related respiratory symptoms was significantly lower in 2017–2018 than in the 2 earlier periods. Among the protective factors, the increasing rate of breastfeeding might be partly responsible for the observed reduced prevalence of current asthma and exercise-induced wheeze, but not physician-diagnosed asthma. The presence of pets in the house was the risk factor that correlated with the prevalence of nocturnal cough. Pearson correlation analysis showed a significant correlation of the prevalence of physician-diagnosed asthma, current asthma, and exercise-induced wheezing with the concentrations of air pollutant particles with aerodynamic diameter ≤10 μM (PM₁₀) (r = 0.84, 0.77 and 0.81, respectively).

Conclusion

The prevalence of asthma and related respiratory symptoms has declined in elementary school-age children in southern Taiwan. The increased prevalence of breastfeeding, decreased rate of the presence of pets in the house, and improvement in outdoor air pollution seem to be related to this decreasing trend of asthma in school children. Our findings will provide the scientific base to empower prevention policy to reverse the trend of childhood asthma prevalence.

Trial registration

N/A

Prevalence and risk factors of asthma among school going children in urban area of North India

Introduction

Bronchial asthma is a chronic respiratory illness of global importance. Recent reports depict the increasing prevalence of this disorder in urban areas.

Methods

An observational study was designed with a sample size of 1163 children from grade 4 to grade 12, involving 8 randomly selected schools in 2015-2016. Modified International Study of Asthma and Allergy in Childhood [ISAAC] questionnaire in local language [Hindi version] was used for data collection. The data of assessed risk factors were collected and analysed.

Results

Prevalence of asthma in the studied population was 2.8%. Multivariate analysis revealed a significant association of risk of asthma with use of firewood kitchener for cooking, keeping pet animals at home, high body mass index (BMI), absence of ventilator measures like chimney and aero-vent. Logistic regression analysis revealed use of firewood kitchener for cooking (odds ratio (OR) = 4.9, 95% confidence interval (CI) = 2.93-11.3), absence of smoke outlet (OR 2.8, 95% CI 1.3-5.8) and keeping pet animals (OR 3.2, CI 1.6-6.8) at home were observed to be significantly associated with asthma.

Conclusion

Prevalence of asthma in our cohort was significantly lesser than that of developed world. Household smoke was the most conspicuous risk factor contributory to childhood asthma in this part of world.

Association between pet ownership and physical activity levels, atopic conditions, and mental health in Singapore: a propensity score-matched analysis

Although existing literature increasingly suggests a positive influence of pet ownership on human physical activity levels, results from many European, American, and Japanese studies have been inconsistent. How pet ownership impacts mental health and atopy is likewise controversial and whether distinct demographic subgroups experience differential effects is unclear. This cross-sectional study surveyed participants (n = 823) via a self-administered online questionnaire. Comparisons of outcomes between pet owners and non-pet owners with subgroup analyses were performed within a propensity score-matched subset (n = 566) of respondents. There were no differences in physical activity levels or mental health scores between pet owners and non-pet owners. In subgroup analyses, compared to non-pet owners, main pet caregivers reported 14.1 (95% CI 2.79–25.3) and 19.0 (95% CI 4.70–33.3) more minutes per week of moderate- and vigorous-intensity physical activity respectively and higher SF-36 emotional well-being (β = 2.7, 95% CI 0.100–5.32) and energy scores (β = 3.8, 95% CI 0.410–7.27). Age was a significant effect modifier of the association between pet ownership and emotional well-being, energy and social functioning scores, with greater scores above the ages of 39, 35 and 39 years old respectively (interaction p = 0.043, 0.044, 0.042). Finally, pet acquisition was associated with worsening of allergic rhinitis, while pet ownership cessation was associated with improvement of allergic rhinitis and eczema symptoms. To our knowledge, this is the first study addressing the public health impact of pet ownership in Southeast Asia and its findings add contextual nuance to suggest potential benefits derived from pet ownership.

Age Differences in Pet Sensitization by Pet Ownership

OBJECTIVES

The association between pet sensitization and pet ownership remains unclear. Therefore, we aimed to elucidate the association between pet sensitization and pet ownership by age.

METHODS

We retrospectively reviewed 2,883 patients who visited our allergy clinic for nasal symptoms from January 2003 to December 2014, of whom 1,957 patients with data on skin-prick tests and questionnaire responses were included and divided into adults (age >19 years) and children (age ≤19 years). The association between pet sensitization and pet ownership was evaluated in both groups.

RESULTS

Among children, dog and cat sensitization showed no associations with dog and cat ownership, respectively. However, among adults, dog sensitization was significantly associated with dog ownership (odds ratio [OR], 3.283; P<0.001), and cat sensitization with cat ownership (OR, 13.732; P<0.001). After adjustment for age, sex, familial history of allergy, sinusitis, diabetes mellitus, other pet ownership, and non-pet sensitization, significant associations remained between dog sensitization and dog ownership (adjusted OR [aOR], 3.881; P<0.001), and between cat sensitization and cat ownership (aOR, 10.804; P<0.001) among adults. Dog ownership did not show any association with allergic rhinitis, asthma, or atopic dermatitis, whereas atopic dermatitis had a significant association with cat ownership in adults (aOR, 4.840; P<0.001).

CONCLUSION

Pet ownership in adulthood increased the risk of pet sensitization. However, pet ownership was not associated with the prevalence of atopic disorders, regardless of age, except for atopic dermatitis and cat ownership in adults.

Effect of Exposure to Cats and Dogs on the Risk of Asthma and Allergic Rhinitis: A Systematic Review and Meta-analysis

BACKGROUND

Controversies persist regarding whether exposure to cat or dog increases the risk of asthma and allergic rhinitis.

OBJECTIVE

This meta-analysis aimed to assess the associations between exposure to cats or dogs and the development of asthma and allergic rhinitis.

METHODS

A systematic review was performed to identify case-control and cohort studies before May 2019, evaluating the association between exposure to cats and dogs and the risk of asthma and rhinitis. The risk of bias was assessed using the Newcastle-Ottawa Scale. The odds ratios (ORs) and risk ratios (RRs) were pooled for case-control and cohort studies, respectively. Subgroup analyses were performed on prespecified study-level characteristics.

RESULTS

The meta-analysis of 34 cohort studies showed a protective role of exposure to cats [RR: 0.88, 95% confidence interval (CI): 0.77-0.99] or dogs (RR: 0.85, 95% CI: 0.73-0.97) in the development of asthma. The subgroup analysis of birth cohort (RR: 0.74, 95% CI: 0.56-0.93) and children population (RR: 0.83, 95% CI: 0.70-0.96) also suggested a favorable role of exposure to dogs in the development of asthma. Pooled evidence from 13 case-control studies indicated no significant impact of cats (OR: 1.66, 95% CI: 0.39-2.94) and dogs (OR: 1.22, 95% CI: 0.92-1.52) on the development of asthma. A pooled analysis of five cohort studies showed a favorable effect of exposure to cats (RR: 0.60, 95% CI: 0.33-0.86) or dogs (RR: 0.68, 95% CI 0.44-0.90) on the development of allergic rhinitis.

CONCLUSION

The findings indicated a protective effect of exposure to cats and dogs, especially ownership, on the development of asthma and allergic rhinitis.

Associations of dog and cat ownership with wheezing and asthma in children: Pilot study of the Japan Environment and children's study

Objectives

No previous study has used repeated measures data to examine the associations of dog/cat ownership with wheezing and asthma prevalence among children. This prospective study used repeated measurers analysis to determine whether dog/cat ownership in childhood is an independent risk factor for wheezing and asthma, after adjustment for gestational, socio-economical, and demographical confounders confounders, in Japan.

Methods

We conducted a multicenter pilot study of the Japan Environment and Children's Study (JECS) during 2009–2010. Among 440 newborn infants enrolled, 410 (52.8% males) were evaluated for dog/cat ownership in the home and history of wheezing and asthma in five follow-up questionnaire surveys (until age 6 years). Dog/cat ownership during follow-up period was categorized into four groups: 7.6% were long-term dog/cat owners, 5.9% were toddler-age owners, 5.9% were preschool-age owners, and 80.7% were never owners.

Results

The prevalence of wheezing during follow-up period increased from 20.8% to 35.4% and the prevalence of asthma increased from 1.3% to 16.3%. A fitted logistic generalized estimating equation models including important confounders showed no significant associations of the interaction between dog and/or cat ownership and follow-up time with the risks of wheezing and asthma. However, the risks of wheezing and asthma were slightly lower for long-term and toddler-age dog/cat owners than for preschool-age and never owners.

Conclusions

The present findings suggest that dog and cat ownership from toddler-age does not increase the risks of wheezing and asthma compared with never owners among Japanese children.

The time window of pet ownership exposure modifies the relationship of Environmental Tobacco Smoke with lung function: A large population-based cohort study

There is a large body of evidence linking Environmental Tobacco Smoke (ETS) exposure with impaired lung function. However, it is not known whether exposure to pets modifies this relationship. To investigate if pet ownership changes the association between ETS exposure and lung function, a population-based sample of 7326 children, 7-14 years old, were randomly recruited from 24 districts in northeast China. Lung function including forced vital capacity (FVC), forced expiratory volume in 1 s (FEV₁), peak expiratory flow (PEF), and maximal mid-expiratory flow (MMEF) was measured by spirometry, while pet ownership time periods and ETS exposure were collected by questionnaire. Two-level regression analysis was done, with covariates controlled for. The results showed pet exposure in certain early lifetime windows modified the associations of ETS exposure on decreased lung function in children. Among children exposed to current ETS, those exposed to pets in utero had greater reductions in lung function (for instance: OR for reduced FVC (<85% predicted) = 10.86; 95% CI: 3.80-30.97) than those not exposed to pets in utero (OR = 2.32; 95% CI: 1.76-3.05) (p_interaction = 0.005). While, children exposed to current pet ownership reduced the lung function impairment induced by ETS exposure during the first 2 years of life and/or ETS exposure during pregnancy, especially for FVC impairment. For instance, OR (95%CI) for reduced FVC (<85% predicted) was 0.81 (0.56, 1.18) and 1.42 (1.15, 1.74), respectively, for children with or without current pet ownership exposed to ETS during the first 2 years of life (p_interaction = 0.010). Furthermore, pet type or number of pets did not significantly modify associations between ETS exposure and lung function. In conclusion, the timing of pet ownership modified associations between ETS exposure and lung function, pet ownership in utero and during the first 2 years of life significantly worsened the adverse impacts of passive smoking on lung function.

Does new sensitization correlate with nasal symptoms in children with allergic rhinitis?

OBJECTIVES

To evaluate the correlation between the increased number of sensitized allergens and nasal symptoms in patients with allergic rhinitis who were sensitized to house dust mites (HDMs).

METHODS

Among the patients who were enrolled in the Allergic Rhinitis Cohort Study for Kids, 174 children with rhinitis symptoms who were sensitized to HDMs were included in the analysis. Skin prick tests, serum total immunoglobulin E, eosinophil count, and bronchial provocation tests were carried out during the initial and 3-year follow-up visits. The patients were divided into two groups depending on the change in the number of sensitized allergens: increased number of sensitized allergens (group I) and maintained or reduced number of sensitized allergens (group II).

RESULTS

In the analysis of allergen sensitization from baseline to the 3-year follow-up, no significant correlation was observed between the changes in the number of allergens and the total nasal visual analog scale score (R²  < 0.001, P = .813). Furthermore, the comparison of demographic data and immunological factors between groups I and II did not show any significant differences. The changes in bronchial hyper-responsiveness were not significantly different between the two groups (P = 1.000).

CONCLUSION

New sensitization may not be correlated with nasal symptoms in patients in Asian countries where HDMs play a major role as a dominant allergen. Although further investigation must be conducted, the importance of new sensitization as an indicator of treatment outcome should be reconsidered in individuals in Asia.

LEVEL OF EVIDENCE

2b Laryngoscope, 130: 1864-1871, 2020.

Role of timing of exposure to pets and dampness or mould on asthma and sensitization in adolescence

BACKGROUND

Pet and dampness or mould exposure are considered risk factors for asthma and sensitization. It is unclear whether timing of exposure to these factors is differentially associated with asthma risk and sensitization in adolescence.

OBJECTIVE

We investigated the role of timing of pet and dampness or mould exposure in asthma and sensitization in adolescence. Understanding this role is essential to build targeted prevention strategies.

METHODS

We used data from 1871 participants of the Dutch Prevention and Incidence of Asthma and Mite Allergy (PIAMA) cohort. Residential exposure to pets, dampness or mould was assessed by repeated parental questionnaires. We used asthma data from the 17-year questionnaire and sensitization data from the 16-year medical examination. We characterized timing using longitudinal exposure patterns from pregnancy till age 17 using longitudinal latent class growth modelling. We used logistic regression models to analyse associations of exposure patterns with asthma at age 17 and sensitization at age 16.

RESULTS

For none of the time windows, exposure to pets and dampness or mould was associated with asthma at age 17, but a lower sensitization risk at age 16 was suggested, for example the odds ratio (95% confidence interval) for sensitization was 0.63 (0.35-1.11) and 0.69 (0.44-1.08) for early life and persistently high pet exposure, respectively, compared with very low exposure. An inverse association was also suggested for sensitization and moderate early childhood dampness or mould exposure (0.71 [0.42-1.19]).

CONCLUSION AND CLINICAL RELEVANCE

Different timing of pet and dampness or mould exposure was not associated with asthma, but lower risk of sensitization in adolescence was suggested, which could be partly attributable to reversed causation. Current findings are not sufficient to recommend pet avoidance to prevent allergic disease. More prospective studies are needed to obtain insights that can be used in clinical practice.

The association of ambient PM2.5 with school absence and symptoms in schoolchildren: a panel study

BACKGROUND

Children are a susceptible population to exposure of ambient fine particulate air pollution (PM_2.5), and the associated symptoms are sensitive prevalent indicators of morbidity. However, few studies to date investigate the association between PM_2.5 exposure and school absence and symptoms.

METHODS

In a panel study including 20,291 observations in 615 schoolchildren 8-13 years of age, we asked the participants to record their school absence and symptoms on every school day from 17 November to 31 December 2014 in Jinan, China. We used the generalized linear mixed effects models to examine the adverse effects of ambient PM_2.5 on school absence and symptoms, adjusting for covariates including meteorological and individual factors.

RESULTS

The 3-day moving average of PM_2.5 was significantly associated with school absence (1.37; 95% CI: 1.07-1.74) and increases in symptoms of the throat (1.03; 95% CI: 1.00-1.05), nose (1.03; 95% CI: 1.01-1.06), and skin (1.09; 95% CI: 1.06-1.12). High PM_2.5 exposure also increased the risks of individual symptoms, especially for cough (1.02; 95% CI: 1.00-1.04), sneezing (1.03; 95% CI: 1.00-1.07), and stuffy nose (1.09; 95% CI: 1.02-1.17).

CONCLUSION

High PM_2.5 exposure is a risk factor for the health of schoolchildren. Allocation of medical resources for children should take into account the ambient PM_2.5 concentrations and be proportioned accordingly.

Pet keeping in childhood and asthma and allergy among children in Tianjin area, China

This study aims to find out the relationship between pet keeping in childhood and asthma and allergy among children aged 0–8 years old in Tianjin, China. Parental or guardians reports of 7360 children were analyzed. 1490 (21.6%) families kept pets at the time of the survey (current), among them 4.0% cats, and 14.7% dogs. For the first year of life of children (early), 1196 (18.4%) families kept pets, and among them 3.2% cats, and 13.7% dogs. Exposure to a pet in early childhood significantly increased the risk of current wheeze, current dry cough, and diagnosed rhinitis. 17.9% of parents reported an avoidance behavior, i.e., had removed or refrained a pet due to asthma or allergy in the family. After adjustment for avoidance behavior, the negative effect of pet keeping on children’s health became even more obvious, with e.g. an AOR of 3.37 (1.58–7.19) for diagnosed asthma, 3.60 (2.07–6.27) for diagnosed rhinitis, 1.92 (1.31–2.81) for diagnosed eczema. A dose-response relationship between pet keeping at current and current wheeze, current eczema and diagnosed eczema was found. In conclusion, pet exposure in early life of children in Tianjin is a risk factor for asthma and allergies among children aged 0–8 years old.

The role of the indoor environment: Residential determinants of allergy, asthma and pulmonary function in children from a US-Mexico border community

The El Paso Children's Health Study examined environmental risk factors for allergy and asthma among fourth and fifth grade schoolchildren living in a major United States-Mexico border city. Complete questionnaire information was available for 5210 children, while adequate pulmonary function data were available for a subset of 1874. Herein we studied indoor environmental health risk factors for allergy and asthma. Several indoor environmental risk factors were associated with allergy and asthma. In particular, we found that ant and spider pest problems, pet dogs, fireplace heat, central air conditioning, humidifier use, and cooking with gas stoves were positively associated with both allergy and asthma prevalence. With regards to asthma severity, our analysis indicated that exposure to pet dogs increased monotonically with increasing asthma severity while the lack of any heat source and gas stove use for cooking decreased monotonically with increasing asthma severity. Lung function also decreased among children who lived in homes with reported cockroach pest problem in the past year without concurrent use of pesticides. These effects on pulmonary function were present even after excluding children with a current physician's diagnosis of asthma. Clinicians and public health professionals may need to look closely at the contribution of these indoor risk factors on pulmonary health and quality of life among susceptible populations.

Environmental Air Pollutants as Risk Factors for Asthma Among Children Seen in Pediatric Clinics in UKMMC, Kuala Lumpur

The prevalence of asthma is increasing, especially among children in Malaysia, with environmental factors as one of the main preventable contributors. The aim of this study was to determine the association between environmental air pollutants and the occurrence of asthma among children seen in pediatric clinics in Universiti Kebangsaan Malaysia Medical Center (UKMMC), Kuala Lumpur. An unmatched case control study among children who attended the pediatric clinic was carried out from May to August 2015. A total of 223 children who were diagnosed with asthma (105 cases) and who did not have asthma (118 controls) were included in this study. Their parents or caregivers were interviewed using questionnaires modified from the International Study of Asthma and Allergies in Childhood. Data obtained were analyzed using SPSS software version 20. There was a higher risk of asthma in those who had carpet at home (OR = 2.15 CI [1.25-3.68]), those who lived within 200 m of heavy traffic (OR = 1.72 CI [1.01-2.93]), and those who were exposed to lorry fumes (OR = 2.61. CI [1.38-4.93]). Environmental air pollutants increased the risk of asthma among children in Malaysia. Exposure to congested roads, lorry fumes, and indoor carpet were associated with asthma among children in this study. Parents or caretakers of children with asthma should be given adequate education on the prevention of asthmatic attack among these children.

Cat exposure in early life decreases asthma risk from the 17q21 high-risk variant

BACKGROUND

Early-life exposure to cats and dogs has shown diverging associations with childhood asthma risk, and gene-environment interaction is one possible explanation.

OBJECTIVES

We investigated interactions between cat and dog exposure and single nucleotide polymorphism rs7216389 variants in the chromosome 17q21 locus, the strongest known genetic risk factor for childhood asthma.

METHODS

Genotyping was performed in 377 children from the at-risk Copenhagen Prospective Studies on Asthma in Childhood₂₀₀₀. The primary end point was the development of asthma until age 12 years. The secondary end point was the number of episodes with pneumonia and bronchiolitis from 0 to 3 years of age. Exposures included cat and dog ownership from birth and cat and dog allergen levels in bedding at age 1 year. Replication was performed in the unselected COPSAC₂₀₁₀ cohort with follow-up until 5 years of age.

RESULTS

Cat and/or dog exposure from birth was associated with a lower prevalence of asthma among children with the rs7216389 high-risk TT genotype (adjusted hazard ratio, 0.16; 95% CI, 0.04-0.71; P = .015), with no effect in those with the CC/CT genotype (adjusted P = .283), demonstrating interaction between cat and dog exposure and the rs7216389 genotype (adjusted P = .044). Cat allergen levels were inversely associated with asthma development in children with the TT genotype (adjusted hazard ratio, 0.83; 95% CI, 0.71-0.97; P = .022), supporting the cat-rs7216389 genotype interaction (adjusted P = .008). Dog allergen exposure did not show such interaction. Furthermore, the TT genotype was associated with higher risk of pneumonia and bronchiolitis, and this increased risk was likewise decreased in children exposed to cat. Replication showed similar effects on asthma risk.

CONCLUSION

The observed gene-environment interaction suggests a role of early-life exposure, especially to cat, for attenuating the risk of childhood asthma, pneumonia, and bronchiolitis in genetically susceptible subjects.

The association between substantiated childhood maltreatment, asthma and lung function: A prospective investigation

BACKGROUND

Asthma reflects multiple and likely complex causal pathways. We investigate the possibility that childhood maltreatment is one such causal pathway. Childhood maltreatment can be interpreted as a form of early life adversity and like other life adversities may predict a range of negative health outcomes, including asthma.

METHODS

A total of 3762 young adults (52.63% female) from the Mater Hospital-University of Queensland Study of Pregnancy (MUSP) participated in this study. MUSP is a prospective Australian birth cohort study of mothers consecutively recruited during their first antenatal clinic visit at Brisbane's Mater Hospital from 1981 to 1983. The study followed both mother-child dyads to the age of 21years after birth. Participants reported whether they had been diagnosed by a physician with asthma by the 21-year follow-up. Trained research assistants also performed gender- and height-standardized lung function tests using a Spirobank G spirometer system attached to a laptop computer. We linked this dataset with data obtained from the child protection services and which comprised all substantiated cases of childhood maltreatment in the MUSP cohort. Substantiations of childhood maltreatment included children in an age range of 0-14years.

RESULTS

The experience of any childhood maltreatment, particularly emotional abuse, was independently associated with self-reported physician-diagnosed asthma by the 21-year follow-up. The association was no longer significant after adjustment for a range of confounders and covariates in neglected children. Childhood maltreatment, including multiple events, was not associated with lung function in adjusted models.

CONCLUSIONS

Childhood maltreatment, including emotional abuse, was associated with lifetime ever asthma. This was in contrast to the absence of an association with objective measures of lung function. More research is indicated on the effect of childhood maltreatment on lung function using objective measures. In the meantime, there should be a greater awareness of the potential impact of childhood maltreatment on the potential to develop asthma, as well as of the possibility that asthma in adulthood may precede childhood maltreatment.

Prevalence and risk factors for wheezing in infants in the region of Pamplona, Spain

BACKGROUND

Wheezing in the first year of life affects the baby's and family's quality of life. Risk factors such as male gender, nursery attending or a family history of asthma, and protective factors such as breastfeeding more than six months have been previously described. The aim of this study is to study the prevalence and risk factors for wheezing ever and recurrent wheezing in the first year of life in infants in the region of Pamplona, Spain.

MATERIAL AND METHODS

This cross-sectional study was part of the International Study of Wheezing in Infants (Estudio Internacional de Sibilancias en Lactantes, EISL). Between 2006 and 2008, participating families answered a standardised validated questionnaire on respiratory symptoms, environmental factors or family issues. An analysis with the chi square test (statistical significance p<0.05) identified the risk factors for wheezing ever and recurrent wheezing, which were assessed using logistic regression.

RESULTS

1065 questionnaires were answered. The prevalence of wheezing ever and recurrent wheezing were 31.2% and 12.3%, respectively. Male gender (p=<0.001), a history of pneumonia (p=<0.001) or nursery attendance (p=<0.001) were some of the risk factors found for wheezing ever. Infant eczema (p=<0.001), nursery attendance (p=<0.001) or prematurity (p=<0.001) were risk factors for recurrent wheezing. No associations with duration of breastfeeding (p=0.116 and p=0.851) or mould stains at home (p=0.153 and p=0.992) were found.

CONCLUSION

The study of prevalence and risk factors for wheezing shows the importance of this public health problem, and allows the development of control and treatment strategies against preventable factors.

In utero exposure to pets is associated with asthma and wheezing in Mexican American children

OBJECTIVE

To examine the associations of in utero and early life exposure to cats/dogs and birds with the risk of lifetime doctor-diagnosed asthma and other respiratory conditions in a sample of Mexican American (MA) children 4-18 years of age.

METHODS

This study is a population-based cross-sectional investigation of 1816 MA children. We conducted multiple logistic models examining the relationship of asthma and wheezing with exposures to cats/dogs and birds in utero, infancy and at the time of the survey adjusted for country of birth, family history of asthma/allergies, antibiotics use in infancy and other covariates.

RESULTS

In adjusted analyses, in utero exposure to cats/dogs and birds jointly was associated with increased odds of asthma (adjusted odds ratio (aOR): 2.89; 95% confidence interval (CI): 1.34-6.23), ever wheezing (aOR: 1.96; 95% CI: 1.11-3.46) and current exercise-induced wheezing (aOR: 3.16; 95% CI: 1.27-7.85) compared to children not exposed to these pets in utero. Children who were exposed to both cats/dogs and birds in utero had an elevated, albeit statistically non-significant, odds of current wheezing. Exposures in infancy and at the time of the survey to cats/dogs and birds were not associated with asthma or wheezing.

CONCLUSIONS

In utero exposure to pets might be associated with an increased risk of asthma and respiratory conditions in a sample of non-affluent MA children.

Associations of Pet Ownership with Wheezing and Lung Function in Childhood: Findings from a UK Birth Cohort

Background

Asthma is a heterogeneous condition and differential effects of pet ownership on non-atopic versus atopic asthma have been reported. The aim of this study was to investigate whether pet ownership during pregnancy and early childhood was associated with wheezing from birth to age 7 years and with lung function at age 8 years in a UK population-based birth cohort.

Methods

Data from the Avon Longitudinal Study of Parents and Children (ALSPAC) were used to investigate associations of pet ownership at six time-points from pregnancy to age 7 years with concurrent episodes of wheezing, wheezing trajectories (phenotypes) and lung function at age 8 years using logistic regression models adjusted for child’s sex, maternal history of asthma/atopy, maternal smoking during pregnancy, and family adversity.

Results

4,706 children had complete data on pet ownership and wheezing. From birth to age 7 years, cat ownership was associated with an overall 6% lower odds of wheezing (OR=0.94 (0.89-0.99)). Rabbit and rodent ownership was associated with 21% (OR=1.21 (1.12-1.31)) and 11% (OR=1.11 (1.02–1.21)) higher odds of wheezing, respectively, with strongest effects evident during infancy. Rabbit and rodent ownership was positively associated with a ‘persistent wheeze’ phenotype. Pet ownership was not associated with lung function at age 8 years, with the exception of positive associations of rodent and bird ownership with better lung function.

Conclusions

Cat ownership was associated with reduced risk, and rabbit and rodent ownership with increased risk, of wheezing during childhood. The mechanisms behind these differential effects warrant further investigation.

Contributing factors to the development of childhood asthma: working toward risk minimization

Asthma is the most common chronic disease in childhood, and considerable research has been undertaken to find ways to prevent its development and reduce its prevalence. For such interventions to be successful, risk factors for asthma emergence should be identified and clearly defined. Data are robust for some of them, including atopy, viral infections and exposure to airborne irritants, whereas it is less conclusive for others, such as aeroallergen exposure and bacterial infections. Several interventions for asthma prevention, including avoidance and pharmacotherapy, have been attempted. However, most of them have furnished equivocal results. Various issues hinder the establishment of risk factors for asthma development and reduce the effectiveness of interventions, including the complexity of the disease and the fluidity of the developing systems in childhood. In this review, we revisit the evidence on pediatric asthma risk factors and prevention and discuss issues that perplex this field.

Pet ownership is associated with increased risk of non-atopic asthma and reduced risk of atopy in childhood: findings from a UK birth cohort

BACKGROUND

Studies have shown an inverse association of pet ownership with allergy but inconclusive findings for asthma.

OBJECTIVE

To investigate whether pet ownership during pregnancy and childhood was associated with asthma and atopy at the age of 7 in a UK population-based birth cohort.

METHODS

Data from the Avon Longitudinal Study of Parents and Children (ALSPAC) were used to investigate associations of pet ownership at six time points from pregnancy to the age of 7 with asthma, atopy (grass, house dust mite, and cat skin prick test) and atopic vs. non-atopic asthma at the age of 7 using logistic regression models adjusted for child's sex, maternal history of asthma/atopy, maternal smoking during pregnancy, and family adversity.

RESULTS

A total of 3768 children had complete data on pet ownership, asthma, and atopy. Compared with non-ownership, continuous ownership of any pet (before and after the age of 3) was associated with 52% lower odds of atopic asthma [odds ratio (OR) 0.48, 95% CI 0.34-0.68]. Pet ownership tended to be associated with increased risk of non-atopic asthma, particularly rabbits (OR 1.61, 1.04-2.51) and rodents (OR 1.86, 1.15-3.01), comparing continuous vs. non-ownership. Pet ownership was consistently associated with lower odds of sensitization to grass, house dust mite, and cat allergens, but rodent ownership was associated with higher odds of sensitization to rodent allergen. Differential effects of pet ownership on atopic vs. non-atopic asthma were evident for all pet types.

CONCLUSIONS AND CLINICAL RELEVANCE

Pet ownership during pregnancy and childhood in this birth cohort was consistently associated with a reduced risk of aeroallergen sensitization and atopic asthma at the age of 7, but tended to be associated (particularly for rabbits and rodents) with an increased risk of non-atopic asthma. The opposing effects on atopy vs. non-atopic asthma might be considered by parents when they are deciding whether to acquire a pet.

A milestone in house dust-mite-allergen immunotherapy: the new sublingual tablet S-524101 (actair)

Subcutaneous allergen-specific immunotherapy has long been used in the treatment of allergic rhinitis and/or asthma and its efficacy has been confirmed. However, due to the discomfort of injections and the risk of severe adverse reactions, alternative routes of allergen administration have emerged. Delivery of allergens through the mucosal route had been proposed and investigated thoroughly, confirming the sublingual route to be the most efficacious. Later, the efficacy and safety of this route have been documented by numerous controlled trials both for house dust mite (HDM) and pollens. Recently, sublingual orodispersable grass pollen allergen tablets were in use followed by the newly developed HDM allergen tablets with satisfactory clinical results: Moreover, very recently 1 year of HDM tablet treatment was demonstrated to exert its clinical efficacy 1 year after discontinuation of tablet IT. The persistence of efficacy after only 1 year of treatment is a new and promising era. Currently, Sublingual Immunotherapy is the most easily administered and safe treatment option until more immunogenic, less allergenic and more efficient allergen extracts are developed.

A Multiple Indicators Multiple Cause (MIMIC) model of respiratory health and household factors in Chinese children: the seven Northeastern cities (SNEC) study

In China, with the rapid economic development and improvement of living standards over the past few decades, the household living environment has shifted dramatically. The aim of the present study is to assess the impact of home environment factors on respiratory symptoms and asthma in Chinese children. Investigators analyzed data collected in the 25 districts from the seven Northeastern cities to examine health effects on respiratory symptoms and asthma in 31,049 children aged 2-14 years. Factor analysis was used to reduce 33 children's lifestyle and household variables to six new 'factor' variables. The multiple indicators multiple causes approach was used to examine the relationship between indoor air pollution and respiratory health status, controlling for covariates. Factor analyses generated six factor variables of potential household risk factors from an original list of 33 variables. The respiratory symptoms and asthma were significantly associated with the recent home renovation factor (estimate = 0.076, p < 0.001), pet ownership factor (estimate = 0.095, p < 0.001), environmental tobacco smoke (ETS) exposure factor (estimate = 0.181, p < 0.001) and PVC-flooring factor (estimate = 0.031, p = 0.007). Home ventilation factor was not related to any respiratory condition (estimate = 0.028, p = 0.074). Independent respiratory health effects existed for multiple household environmental factors recent home renovation, pet ownership, ETS, and PVC-flooring.

Allergy to furry animals: New insights, diagnostic approaches, and challenges

The prevalence of allergy to furry animals has been increasing, and allergy to cats, dogs, or both is considered a major risk factor for the development of asthma and rhinitis. An important step forward in the diagnosis of allergy to furry animals has been made with the introduction of molecular-based allergy diagnostics. A workshop on furry animals was convened to provide an up-to-date assessment of our understanding of (1) the exposure and immune response to the major mammalian allergens, (2) the relationship of these responses (particularly those to specific proteins or components) to symptoms, and (3) the relevance of these specific antibody responses to current or future investigation of patients presenting with allergic diseases. In this review research results discussed at the workshop are presented, including the effect of concomitant exposures from other allergens or microorganisms, the significance of the community prevalence of furry animals, molecular-based allergy diagnostics, and a detailed discussion of cat and dog components.

The quality of life of Brazilian adolescents with asthma: associated clinical and sociodemographic factors

OBJECTIVE

Asthma is the most common chronic disease among adolescents. This study assessed the quality of life (QOL) related to health in adolescents with asthma and its determining factors (demographic, socioeconomic, and clinical). We also separately evaluated each of the parameters that comprised the asthma control classification.

METHODS

This was an observational, cross-sectional study of 114 adolescents who had doctor-diagnosed asthma. QOL was assessed using a version of the Pediatric Asthma Quality of Life Questionnaire (PAQLQ) that was adapted and validated for Brazil, and higher scores indicated a better QOL. The level of asthma control was assessed using the rating system proposed by the Global Initiative for Asthma, and sociodemographic factors were evaluated.

RESULTS

When the averages of the PAQLQ domains and overall scores were compared to the potentially explanatory variables, significantly lower average PAQLQ scores were obtained for individuals with an inadequate level of asthma control (p < 0.001). Of the control components, daytime symptoms, nighttime symptoms, and limited physical activity were related to QOL. However, the use of the β2 agonist and the peak flow functional parameter were not related to QOL.

CONCLUSIONS

The level of asthma control was related to QOL, but this association manifested mainly in the subjective control domains, such as nighttime and daytime symptoms and physical activity limitations. The objective domain for control classification, represented by pulmonary function, was not an independent predictor or determinant of the QOL of adolescent asthma patients.

Epidemiology of Respiratory Allergies and Asthma

Asthma has puzzled and confused physicians from the time of Hippocrates to the present day. The word “asthma” comes from a Greek word meaning “panting” (Keeney 1964), but reference to asthma can also be found in ancient Egyptian, Hebrew, and Indian medical writings (Ellul-Micallef 1976; Unger and Harris 1974). There were clear observations of patients experiencing attacks of asthma in the second century and evidence of disordered anatomy in the lung as far back as the seventeenth century (Dring et al. 1689).

Controversial role of pets in the development of atopy in children

BACKGROUND

Exposure to environmental allergens originating from different sources has been implicated in the sensitization to the respective allergens and development of atopic diseases. Keeping domestic animals is associated with exposure to relevant allergens but there are controversial data whether this exposure promotes or protects from the development of atopy.

DATA SOURCES

We herein reviewed the literature regarding the available data for the exposure to pets (cats and/or dogs) and the development of atopy. For this purpose, we searched the PubMed database.

RESULTS

This review attempts to answer the following questions that arise from the daily practice and the relevant studies, which are: a) is pet keeping associated with sensitization? b) is there an association between keeping pets and the development of asthma, allergic rhinitis and eczema, and, c) what is the underlying mechanism of any possible protective association? Despite the fact that several studies and meta-analyses have been conducted to explore the role of pets in the development of atopy, there are still conflicting pieces of evidence. It seems that there are different effects depending on the type of pets, the time and duration of exposure, and the genetic background of the individual.

CONCLUSION

Further appropriately designed birth cohort studies are needed to explore whether exposure to relevant allergens from pets promotes or protects from the development of atopy.

Association between pet-keeping and asthma in school children

BACKGROUND

The role of pet exposure in childhood asthma and allergy is still controversial. The aim of this study was to investigate the association between pet-keeping during different periods of childhood and asthma and sensitization in school children.

METHODS

One hundred and forty-nine children aged between 7 and 14 years were enrolled in this study. Seventy-four children had current physician-diagnosed asthma, while 75 children did not have asthma. Pet-keeping was investigated by questionnaire. Allergic sensitization to pet allergen was assessed on skin prick tests and specific serum IgE concentration. Logistic regression analysis was performed, taking into account potential confounders.

RESULTS

Early, past and current pet-keeping was not significantly associated with asthma. Neither owning a cat nor dog during childhood was associated with asthma. Early pet-keeping, however, was significantly associated with sensitization to pet allergens (adjusted odds ratio [aOR], 24.11; 95% confidence interval [CI]: 3.28-177.27). Further analysis showed that only early cat-keeping was significantly associated with sensitization to cat allergen (aOR, 51.59; 95%CI: 2.28-1167.07). Keeping a cat or a dog after the first year of life was not associated with sensitization to those allergens.

CONCLUSIONS

Keeping a cat or a dog does not increase risk for asthma. Keeping a cat in the first year of life, however, increases risk of sensitization to cat allergen. Considering that this is a relatively small study, larger, prospective, birth cohort studies are required in Serbia to accurately assess the relationship between pet-keeping, asthma and sensitization.

Exposure to cats: update on risks for sensitization and allergic diseases

Cats are the pets most commonly implicated in the etiology of asthma and allergic disease. However, systematic reviews have concluded that there is a lack of evidence to support the idea that cat exposure in early life increases the risk of allergic disease. Indeed, it appears most likely that cat exposure is protective against allergic diseases. Recent large prospective studies have shown that living with a cat during childhood, especially during the first year of a child's life, could be protective. However, any advice given to the parents should also incorporate how new acquisition of cats can affect other family members, especially those who are already sensitized. Research is urgently needed to determine whether the suggested impact of acquisition of cats in adult life is modified by the person's childhood pet ownership, to help parents who seek advice on whether or not to get a cat.

Pets at birth do not increase allergic disease in at-risk children

BACKGROUND

The literature is contradictory concerning pet exposure and risk of allergic disease in childhood especially among those with a family history of allergy.

OBJECTIVE

To investigate the relationship between cat and dog exposure at birth and allergic outcomes over the first 12 years in a birth cohort selected for familial allergy.

METHODS

A prospective birth cohort of 620 infants with a family history of allergic diseases was recruited. Data on pet keeping, family demographics and cord blood samples were collected at birth. Information on childhood wheeze, eczema and hay fever was collected 18 times in the first 2 years, at 7 years and at 12 years. Skin prick tests were conducted at 2, 7 and 12 years, and in parents. Regression analyses were used to investigate the relevant associations while adjusting for potential confounders.

RESULTS

Exposure to cats or dogs at birth showed a moderate reduction in risk of wheeze (aOR = 0.76; 95% CI 0.53, 1.09) and hay fever (aOR = 0.71; 0.49, 1.02) after 7 years of age. Protective effects were stronger in children of non-sensitized fathers (aOR wheeze 0.55; 0.31, 0.98; aOR hay fever 0.33; 0.15, 0.77 on exposure to cats alone, or cats or dogs at birth). Pet keeping was not related to cord blood IgE or sensitization from 2 to 12 years.

CONCLUSIONS AND CLINICAL RELEVANCE

Pets at birth either decreased or had no effect on allergic disease up to age 12. We found no evidence that exposure to cats or dogs at birth increases the risk of allergic disease in high-risk children.

Exposure to cats and dogs, and symptoms of asthma, rhinoconjunctivitis, and eczema

BACKGROUND

Associations between exposure to cats and dogs and respiratory and allergic outcomes in children have been reported in affluent countries, but little is known about such associations in less-affluent countries.

METHODS

The International Study of Asthma and Allergies in Childhood, phase 3 was carried out in children aged 6-7 years and adolescents aged 13-14 years across the world. Questions about cats and dogs in the home were included in an additional questionnaire. Using logistic regression, we investigated the association between such exposures and symptoms of asthma, rhinoconjunctivitis, and eczema. Adjustments were made for sex, region of the world, language, gross national income per capita, and 10 other covariates.

RESULTS

Among children (6-7 years of age), cat exposure in the first year of life was associated with current symptoms of asthma, wheeze, rhinoconjunctivitis, and eczema, especially in less-affluent countries. Among adolescents (13-14 years of age), we found a positive association between exposure to cats or dogs and symptom prevalence in more-affluent and less-affluent countries. The global multivariate odds ratios for children with complete covariate data were 1.17 (95% confidence interval = 1.08-1.29) for current symptoms of asthma, 1.13 (1.05-1.23) for rhinoconjunctivitis, and 1.38 (1.26-1.52) for eczema. Smaller odds ratios were found for exposure to only dogs. Exposure to only cats was associated with eczema.

CONCLUSION

Early-life exposure to cats is a risk factor for symptoms of asthma, rhinoconjunctivitis, and eczema in 6- to 7-year-old children, especially in less-affluent countries. Current exposure to cats and dogs combined, and only to dogs, is a risk factor for symptom reporting by 13- to 14-year-old adolescents worldwide.

Atopic dermatitis in a high-risk cohort: natural history, associated allergic outcomes, and risk factors

BACKGROUND

Atopic dermatitis (AD) is commonly associated with asthma and other atopic disorders in childhood.

OBJECTIVE

To evaluate the natural history of AD and its association with other allergic outcomes in a high-risk cohort through the age of 7 years.

METHODS

A total of 373 high-risk infants, who had undergone a randomized controlled trial with intervention measures for primary prevention of asthma applied during the first year of life, were assessed for asthma, AD, and allergic sensitization at 1, 2, and 7 years.

RESULTS

The multifaceted intervention program did not reduce AD despite reducing the prevalence of asthma significantly. Sixty-two children (16.6%) had AD during the first 2 years (early-onset AD); of these, 26 continue to have AD at the age of 7 years (persistent), whereas 36 no longer had the disease (nonpersistent) at the age of 7 years. Twenty-three children (6.2%) developed AD only after the age of 2 years (late-onset AD). Early-onset AD, persistent or nonpersistent, was associated with increased risk of allergic sensitization to food allergens within the first 2 years of life and asthma diagnosis at year 7. However, only persistent AD was associated with an increased risk of other atopic diseases and allergic sensitization to food and aeroallergens at year 7. Late-onset AD was not associated with atopic diseases or allergic sensitization at year 7 with the exception of Alternaria alternans.

CONCLUSION

In this cohort of infants at high risk of asthma, early-onset persistent AD, which was highly associated with atopic sensitization, increased the risk of atopic diseases in later childhood and thus appears to be part of the atopic march.

Associations of different phenotypes of wheezing illness in early childhood with environmental variables implicated in the aetiology of asthma

Rationale

Asthma is a complex heterogeneous disease that has increased in prevalence in many industrialised countries. However, the causes of asthma inception remain elusive. Consideration of sub-phenotypes of wheezing may reveal important clues to aetiological risk factors.

Methods

Longitudinal phenotypes capturing population heterogeneity in wheezing reports from birth to 7 years were derived using latent class analysis in the Avon Longitudinal Study of Parents and Children (ALSPAC). Probability of class membership was used to examine the association between five wheezing phenotypes (transient early, prolonged early, intermediate-onset, late-onset, persistent) and early life risk factors for asthma.

Results

Phenotypes had similar patterns and strengths of associations with early environmental factors. Comparing transient early with prolonged early wheezing showed a similar pattern of association with most exposure variables considered in terms of the direction of the effect estimates but with prolonged early wheezing tending to have stronger associations than transient early wheezing except for parity and day care attendance.

Conclusions

Associations with early life risk factors suggested that prolonged early wheeze might be a severe form of transient early wheezing. Although differences were found in the associations of early life risk factors with individual phenotypes, these did not point to novel aetiological pathways. Persistent wheezing phenotype has features suggesting overlap of early and late-onset phenotypes.