Relation between breastfeeding and the prevalence of asthma : the Tokorozawa Childhood Asthma and Pollinosis Study

Health effects associated with exposure to secondhand smoke: a Burden of Proof study

Despite a gradual decline in smoking rates over time, exposure to secondhand smoke (SHS) continues to cause harm to nonsmokers, who are disproportionately children and women living in low- and middle-income countries. We comprehensively reviewed the literature published by July 2022 concerning the adverse impacts of SHS exposure on nine health outcomes. Following, we quantified each exposure-response association accounting for various sources of uncertainty and evaluated the strength of the evidence supporting our analyses using the Burden of Proof Risk Function methodology. We found all nine health outcomes to be associated with SHS exposure. We conservatively estimated that SHS increases the risk of ischemic heart disease, stroke, type 2 diabetes and lung cancer by at least around 8%, 5%, 1% and 1%, respectively, with the evidence supporting these harmful associations rated as weak (two stars). The evidence supporting the harmful associations between SHS and otitis media, asthma, lower respiratory infections, breast cancer and chronic obstructive pulmonary disease was weaker (one star). Despite the weak underlying evidence for these associations, our results reinforce the harmful effects of SHS on health and the need to prioritize advancing efforts to reduce active and passive smoking through a combination of public health policies and education initiatives.

Life Course of Asthma

Asthma is a heterogeneous chronic airway disease that can vary over a lifetime. Although broad categories of asthma by severity and type have been constructed, there remains a tremendous opportunity to discover an approach to managing asthma with additional factors in mind. Many in the field have suggested and are pursuing a novel paradigm shift in how asthma might be better managed, considering the life course of exposures, management priorities, and predicted trajectory of lung function growth. This approach will require a more holistic view of prenatal, postnatal, adolescence, hormonal and gender aspects, and the aging process. In addition, the environment, externally and internally, including in one's genetic code and epigenetic changes, are factors that affect how asthma progresses or becomes more stable in individuals. This chapter focuses on the various influences that may, to differing degrees, affect people with asthma, which can develop at any time in their lives. Shifting the paradigm of thought and strategies for care and advocating for public policies and health delivery that focus on this philosophy is paramount to advance asthma care for all.

Risk factors of asthma in the Asian population: a systematic review and meta-analysis

Background and objective

An increasing trend of asthma prevalence was observed in Asia; however, contributions of environmental and host-related risk factors to the development of this disease remain uncertain. This study aimed to perform a systematic review and meta-analysis for asthma-associated risk factors reported in Asia.

Methods

We systematically searched three public databases (Web of Science, PubMed, and Scopus) in Feb 2021. We only included articles that reported environmental and host-related risk factors associated with asthma in the Asian population. Random-effect meta-analyses were conducted for frequently reported asthma-associated risk factors to provide an overall risk estimate of asthma development.

Results

Of 4030 records obtained from public databases, 289 articles were selected for review. The most frequently reported asthma-associated risk factor was the family history of allergy-related conditions. The random-effect asthma risk estimates (pooled odds ratio, OR) were 4.66 (95% confidence interval (CI): 3.73–5.82) for the family history of asthma, 3.50 (95% CI: 2.62–4.67) for the family history of atopy, 3.57 (95% CI: 3.03–4.22) for the family history of any allergic diseases, 1.96 (95% CI: 1.47–2.61) for the family history of allergic rhinitis, and 2.75 (95% CI: 1.12–6.76) for the family history of atopic dermatitis. For housing-related factors, including the presence of mold, mold spots, mold odor, cockroach, water damage, and incense burning, the random-effect pooled OR ranged from 1.43 to 1.73. Other risk factors with significant pooled OR for asthma development included male gender (1.30, 95% CI: 1.23–1.38), cigarette smoke exposure (1.44, 95% CI: 1.30–1.60), cigarette smoking (1.66, 95% CI: 1.44–1.90), body mass index (BMI)–related parameters (pooled OR ranged from 1.06 to 2.02), various types of air pollution (NO₂, PM10, and O₃; pooled OR ranged from 1.03 to 1.22), and pre- and perinatal factors (low birth weight, preterm birth, and cesarean section; pooled OR ranged from 1.14 to 1.32).

Conclusions

The family history of asthma was the most frequently reported risk factor for asthma development in Asia with the highest risk estimate for asthma development. This suggests a major role of the genetic component in asthma pathogenesis. Further study on asthma genetics is required to improve the current understanding of asthma etiology.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40101-021-00273-x.

Relationship between breastfeeding and asthma prevalence in young children exposed to adverse childhood experiences

OBJECTIVE

To investigate if duration of supplemental breastfeeding is associated with a lower asthma risk and whether adverse childhood experiences (ACEs) early in life influence this relationship in children ages 3 to 5 years.

METHODS

Data were from the 2011-2012 National Survey of Children's Health, a nationally representative cross-sectional survey. Modified Poisson regression models were used to estimate incident risk ratios (IRR) for lifetime and current asthma in young children aged 3 to 5 years (n = 15,642). We tested for effect measure modification using stratified analyses.

RESULTS

Exclusive breastfeeding for at least 6 months or supplemental breastfeeding for children ≥12 months significantly reduced the risk of lifetime asthma prevalence compared to never breastfed children (IRR 0.64; 95% CI: 0.46-0.88, p = 0.007; and IRR 0.68; 95% CI: 0.47-0.99, p = 0.044, respectively), adjusted for covariates. In stratified analyses, breastfeeding reduced the risk of lifetime asthma for children who experienced 1 ACE but not for children who experienced 2 or more ACEs.

CONCLUSION

Exclusive breastfeeding for at least 6 months, with and without supplementation, appears to prevent asthma or delay its onset. The protective effect of breastfeeding was attenuated among children who experienced more than 2 ACEs. The known harmful effects that ACEs have on children's health may outweigh the benefits of breastfeeding in reducing the risk of a child developing asthma. Understanding how specific time periods in a child's life may be most affected by exposure to early life adversities, along with the protective effect of breastfeeding against asthma, are important areas of further study.

Breastfeeding and the risk of childhood asthma: A two-stage instrumental variable analysis to address endogeneity

BACKGROUND

Several explanations for the inconsistent results on the effects of breastfeeding on childhood asthma have been suggested. The purpose of this study was to investigate one unexplored explanation, which is the presence of a potential endogenous relationship between breastfeeding and childhood asthma. Endogeneity exists when an explanatory variable is correlated with the error term for reasons such as selection bias, reverse causality, and unmeasured confounders. Unadjusted endogeneity will bias the effect of breastfeeding on childhood asthma.

METHODS

To investigate potential endogeneity, a cross-sectional study of breastfeeding practices and incidence of childhood asthma in 87 pediatric patients in Georgia, the USA, was conducted using generalized linear modeling and a two-stage instrumental variable analysis. First, the relationship between breastfeeding and childhood asthma was analyzed without considering endogeneity. Second, tests for presence of endogeneity were performed and having detected endogeneity between breastfeeding and childhood asthma, a two-stage instrumental variable analysis was performed. The first stage of this analysis estimated the duration of breastfeeding and the second-stage estimated the risk of childhood asthma.

RESULTS

When endogeneity was not taken into account, duration of breastfeeding was found to significantly increase the risk of childhood asthma (relative risk ratio [RR]=2.020, 95% confidence interval [CI]: [1.143-3.570]). After adjusting for endogeneity, duration of breastfeeding significantly reduced the risk of childhood asthma (RR=0.003, 95% CI: [0.000-0.240]).

CONCLUSION

The findings suggest that researchers should consider evaluating how the presence of endogeneity could affect the relationship between duration of breastfeeding and the risk of childhood asthma.

Breastfeeding duration is inversely associated with asthma in Japanese children aged 3 years

OBJECTIVE

Recent meta-analyses found an inverse relationship between breastfeeding duration and asthma in children. The present cross-sectional study investigated the associations between breastfeeding duration and the prevalence of wheeze and asthma in Japanese children aged 3 years.

METHODS

Subjects were 6412 children who participated in the Kyushu Okinawa Child Health Study. Data were collected using a self-administered questionnaire. Wheeze was defined according to the criteria of the International Study of Asthma and Allergies in Childhood. Asthma was considered present if the child had been diagnosed by a physician as having asthma. Associations of breastfeeding duration with wheeze and asthma were estimated using multivariate generalized estimating equation methods adjusted for maternal, family, and health characteristics.

RESULTS

The prevalence values of wheeze and asthma were 19.5% and 7.0%, respectively. Compared with <4 months of exclusive breastfeeding, exclusive breastfeeding for ≥4 months was not significantly associated with wheeze or asthma. Compared with <10 months of breastfeeding duration regardless of exclusivity, 10 to <14 months, 14 to <19 months, and 19 months or more of breastfeeding duration regardless of exclusivity were independently inversely related to asthma: the adjusted odds ratios [ORs; 95% confidence intervals (CIs)] were 0.69 (0.52-0.91, p = 0.01), 0.73 (0.56-0.97, p = 0.03), and 0.67 (0.51-0.88, p = 0.004), respectively. No association was found between breastfeeding duration regardless of exclusivity and wheeze.

CONCLUSIONS

We confirmed an inverse association between breastfeeding duration regardless of exclusivity and asthma.

Duration and exclusiveness of breastfeeding and school-age lung function and asthma

BACKGROUND

Breastfeeding reduces the risk of asthma in early childhood, but it is not clear whether its effect on respiratory morbidity is still present in later childhood.

OBJECTIVE

To examine the associations of any breastfeeding, breastfeeding duration, and breastfeeding exclusiveness with lung function and asthma in school-aged children and whether associations were influenced by respiratory tract infections and maternal or child's atopic status.

METHODS

This study of 4,464 children was embedded in a population-based prospective cohort study. Information on breastfeeding was obtained by multiple questionnaires from birth until 1 year of age. At 10 years of age, lung function was measured by spirometry, and information on asthma was obtained by questionnaire. Adjusted linear and logistic regression models were used to examine the associations.

RESULTS

Shorter duration of breastfeeding was associated with a lower forced expiratory volume in 1 second (FEV₁) only (z score change, -0.01; 95% confidence interval [CI], -0.02 to -0.00) per month shorter breastfeeding, but not asthma. When categorized, breastfeeding for 2 to 4 months was associated with a lower forced vital capacity (FVC) (z score change, -0.11; 95% CI, -0.20 to -0.03) compared with breastfeeding for 6 months or longer. Nonexclusive breastfeeding for 4 months was associated with a lower FVC (z score change, -0.08; 95% CI, -0.16 to -0.01) compared with exclusive breastfeeding for 4 months. Results did not materially change after additional adjustment for lower respiratory tract infections and were not modified by maternal history of asthma or atopy, child's eczema, or inhalant allergic sensitization.

CONCLUSION

Shorter duration and nonexclusivity of breastfeeding were associated with a lower FEV₁ and FVC but not asthma at school-age.

Diet Hypotheses in Light of the Microbiota Revolution: New Perspectives

From an evolutionary standpoint, allergy has only recently emerged as a significant health problem. Various hypotheses were proposed to explain this, but they all indicated the importance of rapid lifestyle changes, which occurred in industrialized countries in the last few decades. In this review, we discuss evidence from epidemiological and experimental studies that indicate changes in dietary habits may have played an important role in this phenomenon. Based on the example of dietary fiber, we discuss molecular mechanisms behind this and point towards the importance of diet-induced changes in the microbiota. Finally, we reason that future studies unraveling mechanisms governing these changes, along with the development of better tools to manipulate microbiota composition in individuals will be crucial for the design of novel strategies to combat numerous inflammatory disorders, including atopic diseases.

Breastfeeding duration and asthma in Puerto Rican children

RATIONALE

Little is known about breastfeeding and asthma in Puerto Ricans, the ethnic group most affected by this disease in the US. We examined the relation between the currently recommended duration of breastfeeding and asthma in school-aged Puerto Rican children.

METHODS

Case-control study of 1,127 Puerto Rican children aged 6-14 years living in Hartford, Connecticut (n = 449) and San Juan, Puerto Rico (n = 678). Parental recall of breastfeeding was categorized based on duration and according to current guidelines (i.e., none, 0-6 months, and >6 months). Asthma was defined as parental report of physician-diagnosed asthma and wheeze in the previous year. We used logistic regression for the multivariate analysis, which was conducted separately for each study site and for the combined cohort. All multivariate models were adjusted for age, gender, household income, atopy, maternal asthma, body mass index, early-life exposure to environmental tobacco smoke, and (for the combined cohort) study site.

RESULTS

After adjustment for covariates, children who were breastfed for up to 6 months had 30% lower odds of asthma (95% CI = 0.5-1.0, P = 0.04) than those who were not breastfed. In this analysis, breastfeeding for longer than 6 months was not significantly associated with asthma (OR = 1.5, 95% CI = 1.0-2.4, P = 0.06).

CONCLUSIONS

Our results suggest that breastfeeding for up to 6 months (as assessed by parental recall) is associated with decreased odds of asthma in Puerto Rican children, and that there is no additional beneficial effect of breastfeeding for over 6 months. These results support current recommendations on the duration of breastfeeding in an ethnic group at risk for asthma.

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.

CFTR Gene Mutations and Asthma in Indian Children: A Case-Control Study

Cystic Fibrosis Trans membrane conductance regulator (CFTR) gene is an asthma susceptibility gene. In the present study we investigated the possible association of CFTR gene mutations in Indian asthmatic children as compared to controls. The study included 250 asthmatics and 250 age and sex matched controls. Case to control ratio for sample size was 1:1. Genotyping was performed for 24 CFTR gene mutations by ARMS-PCR and PCR-RFLP method. Among 24 CFTR gene mutations, heterozygous allele of R553X mutation was found in 4 (1.6 %) asthmatic cases and 2 (0.8 %) controls. Value of FVC and FEV1/FVC ratio were significantly lower in heterozygous individuals (p value <0.05). No significant difference was observed in the genotype and allele frequency of R553X mutation (OR = 1.339, 95 % CI = 0.755-2.374, p value = 0.685). Furthermore, all wild type homozygous alleles were observed in remaining 23 CFTR gene mutations. Our data concludes that R553X mutation was not significantly associated in Indian asthmatic children.

Breast-feeding and hospitalization for asthma in early childhood: a nationwide longitudinal survey in Japan

OBJECTIVE

Whether or not breast-feeding is protective against asthma among children is still controversial. Therefore, we examined the effects of breast-feeding on hospitalization for asthma in early childhood.

DESIGN

Secondary data analyses of a nationwide longitudinal survey of children in Japan ongoing since 2001, with results collected from 2001 to 2004. We used logistic regression models to evaluate the associations of breast-feeding with hospitalization for asthma in children between the ages of 6 and 42 months, adjusting for children's factors (sex, day-care attendance and presence of older siblings) and maternal factors (educational attainment and smoking habit). Setting All over Japan.

SUBJECTS

Term singleton children with information on feeding practices during infancy (n 43367).

RESULTS

After adjusting for maternal factors and children's factors, exclusive breast-feeding at 6-7 months of age was associated with decreased risk of hospitalization for asthma in children. The adjusted odds ratio was 0.77 (95% CI 0.56, 1.06). One-month longer duration of breast-feeding was associated with a 4% decreased risk of hospitalization for asthma (OR = 0.96; 95% CI 0.92, 0.99).

CONCLUSIONS

The protective effects of breast-feeding on hospitalization for asthma were observed in children between the ages of 6 and 42 months.

Breastfeeding and childhood asthma: systematic review and meta-analysis

Asthma and wheezing disorders are common chronic health problems in childhood. Breastfeeding provides health benefits, but it is not known whether or how breastfeeding decreases the risk of developing asthma. We performed a systematic review and meta-analysis of studies published between 1983 and 2012 on breastfeeding and asthma in children from the general population. We searched the PubMed and Embase databases for cohort, cross-sectional, and case-control studies. We grouped the outcomes into asthma ever, recent asthma, or recent wheezing illness (recent asthma or recent wheeze). Using random-effects meta-analyses, we estimated pooled odds ratios of the association of breastfeeding with the risk for each of these outcomes. We performed meta-regression and stratified meta-analyses. We included 117 of 1,464 titles identified by our search. The pooled odds ratios were 0.78 (95% confidence interval: 0.74, 0.84) for 75 studies analyzing "asthma ever," 0.76 (95% confidence interval: 0.67, 0.86) for 46 studies analyzing "recent asthma," and 0.81 (95% confidence interval: 0.76, 0.87) for 94 studies analyzing recent wheezing illness. After stratification by age, the strong protective association found at ages 0-2 years diminished over time. We found no evidence for differences by study design or study quality or between studies in Western and non-Western countries. A positive association of breastfeeding with reduced asthma/wheezing is supported by the combined evidence of existing studies.

Breastfeeding and wheeze prevalence in pre-schoolers and pre-adolescents: the Genesis and Healthy Growth studies

BACKGROUND

To date, extensive research has been undertaken on a potential link of breastfeeding (BF) to wheezing illnesses. Nevertheless, an association remains to be established, partly due to age-dependent discrepancies and different definitions of exposures/outcomes across studies. We thus investigated the relation of diverse infantile feeding patterns with wheeze/asthma prevalence in two cohorts of children of different ages (preschool and preadolescent).

METHODS

Wheeze ever/in the last 12 months (current) and doctor-diagnosed asthma were retrospectively reported by parents of the participants of two cross-sectional studies: the Genesis study (1871 children aged 1-5) and the Healthy Growth study (1884 children aged 9-13). Information on feeding practices (exclusive breastfeeding vs. mixed vs. formula feeding) and their duration (2 vs. 4 vs. 6 months) was recorded. Perinatal and anthorpometric data were also collected.

RESULTS

In pre-schoolers, regimes that did not entail exclusive BF were positively correlated to current/ever wheeze, both before and after adjustment for confounders. No differences between the associations of regimes with 2, 4 or 6 months of exclusive BF with current/ever wheeze were shown. Furthermore, there was no consistent correlation of feeding practices with physician-diagnosed asthma. In pre-adolescents, no association of infantile feeding patterns with the wheeze/asthma outcomes was observed.

CONCLUSIONS

Exclusive BF is associated with reduced prevalence of current/ever wheeze in pre-schoolers; however, this appears to wane in older children. The association of a period of exclusive BF as low as 2 months with pre-school wheeze prevalence, appeared to be comparable with that of 6 months of exclusivity.

Factors associated with asthma among under-fives in Mulago hospital, Kampala Uganda: a cross sectional study

BACKGROUND

Asthma is the most common chronic childhood illness, with rapidly increasing prevalence in low-income countries. Among young children, asthma is often under-diagnosed.We investigated the factors associated with asthma among under-fives presenting with acute respiratory symptoms at Mulago hospital, Uganda.

METHODS

A hospital-based cross sectional study of 614 children with cough and/or difficult breathing, and fast breathing, was conducted between August 2011 and June 2012. A questionnaire focusing on clinical history of the child was administered to the caretakers. A physical examination and, laboratory and radiological investigations were done. Asthma was defined according to GINA (Global Initiative for Asthma) guidelines which were modified by excluding the symptom of "chest tightness", spirometry/peak expiratory flow measurements and by adding chest x-ray findings to distinguish asthma from pneumonia. A panel of three paediatricians reviewed the participants' case reports and, guided by the study definitions, made a diagnosis of asthma or other. Multivariable logistic regression analysis was done to determine factors independently associated with asthma.

RESULTS

Of the 614 children, 128 (20.8%) had asthma, 125 (20.4%) bronchiolitis, 167 (27.2%) bacterial pneumonia only, 163 (26.5%) viral pneumonia while 31 (5.1%) had other diagnoses including pulmonary tuberculosis. The majority (71.1%) of children with asthma were aged ≥ 12 months. Factors associated with asthma included maternal asthma (AOR 2.4, 95% CI 1.2, 4.6), a history of allergy in the patient (AOR 2.6, 95% CI 1.2, 5.4,), use of gas for cooking (AOR 3.8, 95% CI 1.2, 13.3), prematurity (AOR 9.3, 95% CI 1.2, 83.3) and high level of education of caretaker (AOR 9.1, 95% CI 1.1, 72.8).

CONCLUSION

Maternal asthma, a history of allergy in the patient, use of gas for cooking, prematurity and high level of education of caretaker were significantly associated with asthma. There is need for studies to explore the role of the above factors in development and exacerbation of childhood asthma to provide information that can be used to design strategies for asthma prevention and control.

Asthma in Mexican school-age children is not associated with passive smoking or obesity

Background

Asthma has increased in various regions of the world. The factors associated with the growth in prevalence are still to be determined.

Objective

To evaluate the degree of association of the prevalence of asthma with passive smoking and obesity in school-children in western Mexico.

Methods

A population-based cross-section analytic study. A stratified random sample of 740 primary school pupils of between 6 and 12 years of age was chosen. Asthma, passive smoking and a background of allergic diseases were identified by means of a standardized questionnaire filled out by the parents of the participants. Obesity was identified by means of the body mass index. Proportional sections of population were estimated and the degree of association between asthma (dependent variable) and the independent variables was evaluated by means of multivariate logistic regression.

Results

The following factors of prevalence were found: asthma 8.1%; obesity 19.9%; background of smoking in the father 6.7% and in the mother 13.3%. There was no significant association to be found with asthma in either passive smoking where one of the parents smoked (p = 0.39) or in obesity (p = 0.09). On the other hand, the background of allergic diseases in the mother showed statistically significant association with asthma in the boys (odds ratio = 3.5, 95% confidence interval 1.4 to 8.59), but not in the girls.

Conclusion

With the exception of the maternal background of allergy, neither obesity nor passive smoking are factors associated with asthma in Mexican children.

Understanding the evidence for and against the role of breastfeeding in allergy prevention

The relationship between breastfeeding and allergic disease risk has been controversial. This article reviews the current evidence for the role of breastfeeding in the prevention of allergic disease. We found considerable methodological limitations inherent in most studies evaluating the effect of breastfeeding in allergic disease. Nevertheless, since randomized control trials in breast feeding research would be considered unethical, the evidence remains limited to poorer quality observational studies where participation and recall bias can severely affect the objectivity of the data collected. Furthermore, reporting of type of breastfeeding (exclusive, full or partial) may be biased by a participant's inherent belief system of what they think they should be doing. Current evidence is inconclusive regarding the effect of breastfeeding on the development of eczema, with the most recent systemic review reporting no protective effect. There is insufficient data regarding the effects of breastfeeding on objective measures of food allergy at any age. Studies show a paradoxical effect of breastfeeding on the prevention of asthma, with an apparent protective effect against early wheezing illness in the first years of life yet an increased risk of asthma in later life; however, these findings must be interpreted with caution. Existing studies fail to adequately adjust for confounders, including the critical issues of protection against early life respiratory illnesses and reverse causation. Therefore, it is possible that the effect of breastfeeding on early wheezing illness reflects protection against respiratory infection, the predominant trigger of wheezing in early childhood, rather than a true reduction in risk of asthma. In summary, future research that takes into account the potential contribution of confounding factors and effect modifiers is needed to clarify the role of breastfeeding in development of allergic disease and to inform current clinical guidelines on the prevention of allergic disease.

Asthma in late adolescents of Western Mexico: prevalence and associated factors

INTRODUCTION

Given the number of changes that occur during late adolescence, it is possible that the behavior of asthma may also be different. The aim of our paper is to determine the prevalence of asthma in a population of late adolescents and its possible association with obesity, tobacco smoke exposure and family history of allergic disease.

METHODS AND SUBJECTS

In a cross-sectional, population-based analytical study design, we selected a stratified random sample of subjects aged 15 to 18. By modeling risk through logistic regression, we assessed the relationship between asthma and the following covariables: gender, obesity, excess weight, family history of allergic disease and tobacco smoke exposure.

RESULTS

1,600 subjects were included, and the following prevalences were identified: asthma 7.8%, obesity 9.6%, active smoking in the father 2 9.8%, active smoking in the mother 18.6% and active smoking habit in the study subjects 15.1%. In the final model, a significant association was found between asthma and the following variables: 1) asthma in the mother (adjusted OR [aOR]=2.95, 95% CI, 1.55 to 5.6); 2) history of allergic rhinitis (aOR=4.66, 95% CI, 2.63 to 8.25); and 3) male sex (aOR=1.48, 95% CI, 1.02 to 2.15). No association was seen with obesity or tobacco smoking of the parents.

CONCLUSION

Our results suggest that maternal history of asthma, personal history of allergic rhinitis and male sex are related with asthma late adolescence, while smoking and being overweight are not.

A Cross-Sectional Study to Find Prevalence and Risk Factors for Childhood Asthma in Pune City, India

We aimed to determine current prevalence of asthma and risk factors associated with it in Pune, India. Methods. This was a cross-sectional school-population-based study in which parents of school children aged 6-7 and 13-14 were administered an ISAAC questionnaire and an additional set of questions that detected the presence of potential risk factors known to be associated with asthma during 2008-2009 academic years. Results. Prevalence of current asthma was 6.7% (7% amongst 6-7-year olds and 6.3% amongst 13-14 year olds. Asthma was more common amongst boys (8.1%) than girls (4.9%) and more frequent in students studying in private schools (7.3%) than in those studying in public schools (5.8%). Risk factors such as family history of atopy, caesarian delivery, use of biomass fuel for cooking, absence of separate kitchen, absence of exclusive breastfeeding during the first 6 months of life, preterm birth, snoring, dampness at home, male sex, and parental smoking were significantly associated with asthma. Conclusion. There was a high prevalence of childhood asthma in Pune, India, which was associated with genetic and environmental risk factors.

Systematic review and meta-analysis investigating breast feeding and childhood wheezing illness

There is conflicting evidence concerning the relationship between breast feeding and wheezing illness. The objective of this study was to investigate whether there is any association between breast feeding and wheezing in children aged over 5 years and to discover possible sources of heterogeneity. An electronic search of MEDLINE and EMBASE databases was conducted from January 2000 to June 2010. In addition, reference lists from relevant publications were searched. Birth cohort, cross-sectional and case-control studies were included if they measured any breast feeding or exclusive breast feeding for 3 or 4 months. Wheezing illness, including asthma, was identified based on symptoms, reported diagnosis or objective criteria. Thirty-one publications were identified for meta-analysis. There was no association found between any or exclusive breast feeding and wheezing illness, although there was a high level of heterogeneity between the studies. Subgroup analysis revealed that any breast feeding slightly lowers the odds of wheeze (pooled odds ratio 0.92 [0.86, 0.98]) but slightly increases the odds of asthma defined by specific criteria (pooled odds ratio 1.10 [1.00, 1.22]). This meta-analysis does not provide evidence that breast feeding is protective against wheezing illness in children aged 5 years and over. The difference in the effects of breast feeding according to the nature of the wheezing illness highlights the importance of the heterogeneity of illness phenotypes.

Global strategy for the diagnosis and management of asthma in children 5 years and younger

Asthma is the most common chronic disease of childhood and the leading cause of childhood morbidity from chronic disease as measured by school absences, emergency department visits, and hospitalisation. During the past two decades, many scientific advances have improved our understanding of asthma and our ability to manage and control it effectively. However, in children 5 years and younger, the clinical symptoms of asthma are variable and non-specific. Furthermore, neither airflow limitation nor airway inflammation, the main pathologic hallmarks of the condition, can be assessed routinely in this age group. For this reason, to aid in the diagnosis of asthma in young children, a symptoms-only descriptive approach that includes the definition of various wheezing phenotypes has been recommended. In 1993, the Global Initiative for Asthma (GINA) was implemented to develop a network of individuals, organizations, and public health officials to disseminate information about the care of patients with asthma while at the same time assuring a mechanism to incorporate the results of scientific investigations into asthma care. Since then, GINA has developed and regularly revised a Global Strategy for Asthma Management and Prevention. Publications based on the Global Strategy for Asthma Management and Prevention have been translated into many different languages to promote international collaboration and dissemination of information. In this report, Global Strategy for Asthma Management and Prevention in Children 5 Years and Younger, an effort has been made to present the special challenges that must be taken into account in managing asthma in children during the first 5 years of life, including difficulties with diagnosis, the efficacy and safety of drugs and drug delivery systems, and the lack of data on new therapies. Approaches to these issues will vary among populations in the world based on socioeconomic conditions, genetic diversity, cultural beliefs, and differences in healthcare access and delivery. Patients in this age group are often managed by pediatricians and general practitioners routinely faced with a wide variety of issues related to childhood diseases.

Influence of maternal and perinatal factors on subsequent hospitalisation for asthma in children: evidence from the Oxford record linkage study

Background

There is much interest in the possibility that perinatal factors may influence the risk of disease in later life. We investigated the influence of maternal and perinatal factors on subsequent hospital admission for asthma in children.

Methods

Analysis of data from the Oxford record linkage study (ORLS) to generate a retrospective cohort of 248 612 records of births between 1970 and 1989, with follow-up to records of subsequent hospital admission for 4 017 children with asthma up to 1999.

Results

Univariate analysis showed significant associations between an increased risk of admission for asthma and later years of birth (reflecting the increase in asthma in the 1970s and 1980s), low social class, asthma in the mother, unmarried mothers, maternal smoking in pregnancy, subsequent births compared with first-born, male sex, low birth weight, short gestational age, caesarean delivery, forceps delivery and not being breastfed. Multivariate analysis, identifying each risk factor that had a significant effect independently of other risk factors, confirmed associations with maternal asthma (odds ratio (OR) 3.1, 95% confidence interval 2.7-3.6), male sex (versus female, 1.8, 1.7-2.0), low birth weight (1000-2999 g versus 3000-3999 g, 1.2, 1.1-1.3), maternal smoking (1.1, 1.0-1.3) and delivery by caesarean section (1.2; 1.0-1.3). In those first admitted with asthma under two years old, there were associations with having siblings (e.g. second child compared with first-born, OR 1.3, 1.0-1.7) and short gestational age (24-37 weeks versus 38-41 weeks, 1.6, 1.2-2.2). Multivariate analysis confined to those admitted with asthma aged six years or more, showed associations with maternal asthma (OR 3.8, 3.1-4.7), age of mother (under 25 versus 25-34 at birth, OR 1.16, 1.03-1.31; over 35 versus 25-34, OR 1.4, 1.1-1.7); high social class was protective (1 and 2, compared with 3, 0.72; 0.63-0.82). Hospital admission for asthma in people aged over six was more common in males than females (1.4; 1.2-1.5); but, by the teenage years, the sex ratio reversed and admission was more common in females than males.

Conclusion

Several maternal characteristics and perinatal factors are associated with an elevated risk of hospital admission for asthma in the child in later life.

The effects of birthweight and breastfeeding on asthma among children aged 1-5 years

AIM

Asthma is a major cause of morbidity and mortality among children and has steadily increased in prevalence. The combined effect of birthweight and breastfeeding on childhood asthma remains unclear.

METHODS

In this study, we analysed a nationally representative sample of children aged 1-5 years from the National Health and Nutrition Examination Survey 1999-2002. Logistic regression was performed to examine the hypothesis whether birthweight and breastfeeding are independently associated with the prevalence of asthma after accounting for the complex sampling design. In addition, we sought to describe the relationship between birthweight and childhood asthma and to assess the potentially combined effect between birthweight and breastfeeding on asthma among children aged 1-5 years after considering the possible effects of social and environmental factors.

RESULTS

We found that birthweight (measured continuously) was inversely and linearly associated with the prevalence of childhood asthma (odds ratio (OR) = 0.80 per 1 kg increase in birthweight, 95% confidence interval (CI): 0.65-0.98). Using a categorical variable, low birthweight (LBW) was positively associated with childhood asthma (OR = 1.28, 95% CI: 0.81-2.68). Furthermore, we detected an interaction between birthweight and breastfeeding on childhood asthma. Breastfeeding had a strong protective effect on asthma among children with high birthweight (OR = 0.14, 95% CI: 0.04-0.43) while it had no significant effect on asthma among children with normal birthweight or LBW.

CONCLUSIONS

The mechanisms underlying these relationships remain uncertain and warrant further explanation.

[Prevalence of wheezing in the chest among adults from the 1982 Pelotas birth cohort, Southern Brazil]

OBJECTIVE

To estimate the prevalence of wheezing in the chest among adults, and to explore the effect of some variables on the prevalence of this condition.

METHODS

This was a prospective cohort study on individuals born in the city of Pelotas (Southern Brazil) in 1982. A total of 4,297 subjects was traced in 2004-5, representing 77.4% of the original cohort. Data were collected by means of interviews using the ISAAC (International Study of Asthma and Allergies in Childhood Steering Committee) questionnaire. Associations between the outcome 'occurrence of wheezing in the chest within the 12 months prior to the interview' and the variables of socioeconomic, demographic and birth characteristics were tested by means of multivariable analyses, using Poisson regression.

RESULTS

The prevalence of wheezing over the preceding year was 24.9%. Among the individuals reporting wheezing, 54.6% reported difficulty in sleeping, and 12.9% reported difficulty in speaking due to wheezing. The prevalence of wheezing in the chest was significantly higher among women. This association was maintained in analyses adjusted for non-white skin color, family history of asthma and low socioeconomic level. Among men, there was no significant association in the analyses adjusted for skin color and family income at birth. Family histories of asthma and poverty throughout life presented significant associations with wheezing in the chest. For both sexes, there were no associations with the variables of birth weight and breastfeeding duration.

CONCLUSIONS

The prevalence of wheezing in the chest was high, and subjects with low family income at birth were more likely to have had wheezing in the chest over the preceding year.

[Influence of breastfeeding and diet in the development of allergies in children]

OBJECTIVE

To evaluate the relationship between breastfeeding and the development of allergic diseases (AD).

DESIGN

A cases-controls study.

SETTING

Santander University Hospital, Bucaramanga, Colombia, South America. Level II health care.

PARTICIPANTS

A total of 1460 boys and girls between 3 and 7 years old attending an outpatient clinic.

MAIN MEASUREMENTS

Partial (BF) and exclusive breastfeeding (EBF); relationship between the presence of allergic diseases and BF and EBF, adjusting for the confounding factors due to other exposures using logistic regression.

RESULTS

Out of a total of 1460 patients, 41.6% (95%CI 39.0-44.2) received EBF, while 44.4% (95%CI 41.9-47.0) were partially breastfed. Among those who had an allergy, 34.8% (95%CI 32.4-37.3) had rhinitis, 27.8% (95%CI 25.6-30.2) asthma and 11.6% (95%CI 10.0-13.4) atopic dermatitis; 7.0% (95%CI 5.1-9.3) had the three conditions. To breastfeed exclusively for >or= 3 months is a protective factor for AD (OR 0.70, 95%CI 0.48-1.03). Breastfeeding for 3 months, regardless of whether or not it is exclusive, is a risk factor for AD (OR 2.05, 95%CI 1.47-2.86).

CONCLUSIONS

The recommendation to exclusively breastfeed for as long as possible continues to be valid, as there was a significant preventive impact on the development of AD with the length of time breastfed. Prospective studies including lung function tests and immunological analyses need to be performed to confirm these findings.

Prevalence and correlates of asthma among children in central St. Petersburg, Russia: cross-sectional study

AIM

To estimate the prevalence of asthma among children in central St. Petersburg and to evaluate associations between asthma and socio-demographic, biological, and environmental factors.

METHODS

A cross-sectional study included 1464 children aged 0-18 years from two central districts of St. Petersburg. Parents filled out a questionnaire on children's respiratory health, characteristics at birth, socio-demographic data, housing situation, and their own history of asthma and allergies. The diagnosis of asthma was based on the results of spirometry in children aged > or =5 years and on questionnaire data as reported by parents of younger children. Independent effects of the investigated factors on asthma were assessed by multiple logistic regression analysis. Crude and adjusted odds ratios (OR) with 95% confidence intervals (CI) were calculated.

RESULTS

The estimated prevalence of asthma was 7.4% (95% CI, 6.2-8.8). A history of allergies (OR, 1.6; 95% CI, 1.0-2.6), bronchitis, bronchiolitis, or pneumonia in infancy (OR, 12.2; 95% CI, 7.3-20.5), and self-reported parental allergies (OR, 3.6; 95% CI, 2.2-5.8 for one parent and OR, 7.1; 95% CI, 3.0-17.0 for both parents) were associated with childhood asthma. Children whose mothers were out of work also had higher prevalence of asthma than the reference group (OR, 3.4; 95% CI, 1.1-10.4).

CONCLUSION

The prevalence of asthma is several times higher than what is officially reported for St. Petersburg's inner city children population. Early life events and socio-demographic and biologic factors were associated with asthma in children.

Long-term effects of breastfeeding, maternal smoking during pregnancy, and recurrent lower respiratory tract infections on asthma in children

The effect of breastfeeding on asthma is controversial, which may be explained by related and interacting early childhood risk factors. We assessed the joint effects of a risk-triad consisting of maternal smoking during pregnancy, breastfeeding for less than 3 months, and recurrent lower respiratory tract infections (RLRTI) on physician-diagnosed childhood asthma. The association was assessed in the Isle of Wight birth cohort study (1989-1990) using a repeated measurement approach with data collection at birth, and at ages 1, 2, 4, and 10 years. The population consists of 1,456 children recruited between January 1989 and February 1990. Prenatal smoking, breastfeeding for less than 3 months, and recurrent lower respiratory infections (RLRTI) were combined into eight risk-triads. Relative risks (RR) and 95% confidence intervals were estimated with a log-linear model. The risk-triad involving RLRTI in infancy, maternal smoking during pregnancy, and breastfeeding for less than 3 months showed a stronger association with asthma at ages 4 and 10 compared to other risk-triads (RR of 5.79 for any asthma at ages 1, 2, 4, and 10; and 3.1 for asthma at ages 4 and 10). Of the three individual risk factors, RLRTI appeared to be the major driver of the combined effects in the risk-triads. The effect of RLRTI on asthma was modified by breastfeeding. Breastfeeding for > or = 3 months also attenuated the effect of prenatal smoking on asthma in children without RLRTI. A high proportion of asthma cases in childhood can be prevented by promoting breastfeeding, by preventing smoking during pregnancy, and by avoidance of recurrent lower respiratory tract infections in early childhood.

Breastfeeding and prevalence of allergic diseases in Japanese university students

BACKGROUND

Although historical support exists for the concept that breastfeeding might be protective against allergic diseases, contradictory findings have been observed recently.

OBJECTIVE

To investigate the cumulative prevalence of allergic diseases in Japanese university students and to identify explanatory variables including breastfeeding.

METHODS

From March 18, 2003, through March 29, 2005, a total of 9,615 students newly enrolled at the University of Tokyo responded to a written questionnaire on allergic diseases.

RESULTS

Cumulative prevalence of allergic rhinitis, atopic dermatitis, and asthma was 47.2%, 17.4%, and 9.3%, respectively. These data were closely correlated, and prevalence of any 1 of the 3 diseases significantly increased the odds for historical prevalence of the other 2 (P < .001). Male sex (odds ratio [OR], 1.5; 95% confidence interval [CI], 1.4-1.7) and maternal (OR, 2.2; 95% CI, 2.0-2.5) or paternal (OR, 1.6; 95% CI, 1.4-1.8) history of allergic rhinitis were significant correlates of increased odds for allergic rhinitis. Maternal (OR, 2.7; 95% CI, 1.6-4.5), paternal (OR, 3.8; 95% CI, 2.2-6.6), or sibling (OR, 1.9; 95% CI, 1.5-2.4) history of atopic dermatitis was a significant correlate of increased odds for atopic dermatitis. As for asthma, maternal (OR, 4.9; 95% CI, 3.0-7.9), paternal (OR, 4.0; 95% CI, 2.3-7.0), or sibling (OR, 3.3; 95% CI, 2.4-4.5) history of asthma was a significant correlate of increased odds. Logistic regression analysis showed no consistent evidence of the effects of breastfeeding on the cumulative prevalence.

CONCLUSION

The cumulative prevalence of these diseases among young adults revealed that the effect of breastfeeding is negligible when compared with genetic factors.

Breastfeeding and the risk of wheeze and asthma in Japanese infants: the Osaka Maternal and Child Health Study

Epidemiological evidence for an effect of breastfeeding on asthma continues to be inconclusive. The present prospective study examined the relationship between breastfeeding and the risk of wheeze and asthma in Japanese infants. A birth cohort of 763 infants was followed. The first survey during pregnancy and the second survey between 2 and 9 months postpartum collected information on potential confounding factors. Data on breastfeeding, wheeze, and asthma were obtained from questionnaires in the third survey from 16 to 24 months postpartum. Adjustment was made for maternal age, maternal and paternal history of asthma, atopic eczema, and allergic rhinitis, indoor domestic pets (cats, dogs, birds, or hamsters), family income, maternal and paternal education, maternal smoking during pregnancy, baby's sex, baby's older siblings, household smoking in the same room as the infant, and time of delivery before the third survey. By the third survey, the cumulative incidence of wheeze and asthma was 22.1% and 4.3%, respectively. Neither exclusive breastfeeding for 4 months or more nor partial breastfeeding for 6 months or more were materially related to the risk of wheeze. No measurable association was observed between exclusive breastfeeding for 4 months or more and the risk of asthma. Partial breastfeeding for 6 months or more was inversely related to the risk of asthma although the adjusted odds ratio (OR) was not statistically significant. When infants were stratified according to whether there was a negative or positive allergic history in at least 1 parent, a nearly 40% and 60% decrease, respectively, in the ORs were found for exclusive and partial breastfeeding only in infants without a parental allergic history, although the ORs were not statistically significant. The present prospective study showed no statistically significant relationship between breastfeeding duration and the risk of wheeze or asthma in Japanese infants.

Primary asthma prevention: is it possible?

Asthma, which typically begins in childhood and is the most common chronic disease of childhood, has reached epidemic proportions. Asthma is associated with gene-environment interactions, and there is consensus that a "window of opportunity" exists early in life when environmental factors may influence its development. This review considers biologic and sociologic factors in the development of allergy and asthma. Meta-analysis of studies demonstrates that monoallergen reduction does not impact asthma prevention. However, multifaceted allergen reduction studies have shown clinical benefit. We propose that allergic diseases, including asthma, represent a dysfunctional interaction with our environment and that the increasing prevalence of asthma and allergy herald increased population risk for the development of other inflammatory and autoimmune diseases. Better understanding of the complex factors for asthma and allergies may provide insight into many other chronic complex diseases.

Industrial air pollution and children's respiratory health: a natural experiment in Călăraşi

BACKGROUND

In 1993-1997, we described a high incidence of wheezing in children living near the iron, steel, and coke factory of Călăraşi (Romania). In 1998, the factory was closed.

OBJECTIVE

To investigate the influence of closing the factory on the incidence of wheezing in children living near the factory.

METHODS

We used this natural experiment to compare wheezing occurrence in children below age 2 in an area near the factory and in a village 10 km from the factory (Roseţi). We studied three birth cohorts: those 2 years old before the closing of the factory (group 1), those born before the closing and returning 2 after the closing (group 2), those born after the closing (group 3).

RESULTS

The relative risk (95% CI) of having at least one episode of wheezing during the first life-year was 0.51 (0.30-0.85) in group 3 versus group 1, and 0.95 (0.64-1.40) for group 2 versus group 1. After adjusting for possible confounders, the incidence dropped in Călăraşi (odds ratio [OR] 0.38, 95% CI 0.19-0.76), while it increased in Roseţi (OR 8.36, 95% CI 1.84-38.0). Results for the 2-year incidence were similar.

CONCLUSION

Industrial air pollution by the factory was the main risk factor for wheezing during the first life-years of the children of Călăraşi. Closing the factory resulted in a significant decrease in wheezing incidence rates, which still remained higher than in a nearby village.

Breastfeeding and childhood asthma: a six-year population-based cohort study

Background

The question of the protective effect of breastfeeding on development of asthma has raised substantial interest, but the scientific evidence of the optimal duration of breastfeeding is controversial.

Methods

The authors elaborated the optimal duration of breastfeeding with respect to the risk of asthma primarily, and secondarily to the risk of persistent wheezing, cough and phlegm in school age in a population-based cohort study with the baseline in 1991 and follow-up in 1997. The study population comprised 1984 children aged 7 to 14 years at the end of the follow-up (follow-up rate 77). Information on breastfeeding was based on the baseline survey and information on the health outcomes at the follow-up.

Results

There was a U-shaped relation between breastfeeding and the outcomes with the lowest risk with breastfeeding from four to nine months for asthma and seven to nine months for persistent wheezing, cough and phlegm.

Conclusion

Our results suggest a U shape relation between duration of breastfeeding and risk of asthma with an optimal duration of 4 to 6 months. A true concave relation would explain the inconsistent results from the previous studies.

Effect of prolonged and exclusive breast feeding on risk of allergy and asthma: cluster randomised trial

OBJECTIVE

To assess whether exclusive and prolonged breast feeding reduces the risk of childhood asthma and allergy by age 6.5 years.

DESIGN

Cluster randomised trial.

SETTING

31 Belarussian maternity hospitals and their affiliated polyclinics.

PARTICIPANTS

A total of 17,046 mother-infant pairs were enrolled, of whom 13,889 (81.5%) were followed up at age 6.5 years.

INTERVENTION

Breastfeeding promotion intervention modelled on the WHO/UNICEF baby friendly hospital initiative.

MAIN OUTCOME MEASURES

International study of asthma and allergies in childhood (ISAAC) questionnaire and skin prick tests of five inhalant antigens.

RESULTS

The experimental intervention led to a large increase in exclusive breast feeding at 3 months (44.3% v 6.4%; P<0.001) and a significantly higher prevalence of any breast feeding at all ages up to and including 12 months. The experimental group had no reduction in risks of allergic symptoms and diagnoses or positive skin prick tests. In fact, after exclusion of six sites (three experimental and three control) with suspiciously high rates of positive skin prick tests, risks were significantly increased in the experimental group for four of the five antigens.

CONCLUSIONS

These results do not support a protective effect of prolonged and exclusive breast feeding on asthma or allergy.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN37687716 [controlled-trials.com].

Developing asthma in childhood from exposure to secondhand tobacco smoke: insights from a meta-regression

OBJECTIVE

Studies have identified associations between household secondhand tobacco smoke (SHS) exposure and induction of childhood asthma. However, the true nature and strength of this association remains confounded in many studies, producing inconsistent evidence. To look for sources of potential bias and try to uncover consistent patterns of relative risk estimates (RRs), we conducted a meta-analysis of studies published between 1970 and 2005.

DATA SOURCES

Through an extensive literature search, we identified 38 epidemiologic studies of SHS exposure and the development of childhood asthma (that also controlled for atopy history) from 300 potentially relevant articles.

DATA SYNTHESIS

We observed substantial heterogeneity within initial summary RRs of 1.48 [95% confidence interval (CI), 1.32-1.65], 1.25 (1.21-1.30), and 1.21 (1.08-1.36), for ever, current, and incident asthma, respectively. Lack of control for type of atopy history (familial or child) and child's own smoking status within studies and age category altered summary RRs in separate meta-regressions. After adjusting for these confounding characteristics, consistent patterns of association emerged between SHS exposure and childhood asthma induction. Our summary RR of 1.33 (95% CI, 1.14-1.56) from studies of incident asthma among older children (6-18 years of age) is 1.27 times the estimate from studies of younger children and higher than estimates reported in earlier meta-analyses.

CONCLUSIONS

This new finding indicates that exposure duration may be a more important factor in the induction of asthma than previously understood, and suggests that SHS could be a more fundamental and widespread cause of childhood asthma than some previous meta-analyses have indicated.

Cross-sectional study of allergic disorders associated with breastfeeding in Japan: the Ryukyus Child Health Study

Uncertainties remain as to whether breastfeeding is protective against childhood allergic disorders. Positive relationships of breastfeeding with asthma and atopic eczema were observed in two previous Japanese studies. This cross-sectional study investigated the association between the feeding pattern after birth and the prevalence of allergic disorders during the past 12 months in Japanese schoolchildren. Study subjects were 24,077 children aged 6-15 yr in Okinawa. The outcomes were based on diagnostic criteria from the International Study of Asthma and Allergies in Childhood. Allowance was made for age, sex, number of siblings, smoking in the household, paternal and maternal history of asthma, atopic eczema, and allergic rhinitis, and paternal and maternal educational level. Breastfeeding, regardless of exclusivity, for 13 months or longer and exclusive breastfeeding for 4-11 months were independently associated with a higher prevalence of atopic eczema, particularly among children without a parental allergic history. A clear positive dose-response relationship was observed between prolonged duration of breastfeeding, regardless of exclusivity, but not exclusive breastfeeding, and the prevalence of atopic eczema. We found a significant positive trend for atopic eczema across the three categories (formula milk, partial and exclusive breastfeeding) in the first 4 months of life although the odds ratio for exclusive breastfeeding was not statistically significant. No material association was found between the feeding pattern after birth and the prevalence of wheeze or allergic rhinoconjunctivitis. Prolonged breastfeeding may be associated with a higher prevalence of atopic eczema in Japanese children.

The relationship of breast-feeding, overweight, and asthma in preadolescents

BACKGROUND

Breast-feeding is suggested to be associated with overweight or asthma in children. Overweight and asthma may share common environmental influences of which breast-feeding may be one.

OBJECTIVE

We evaluated whether short duration of exclusive breast-feeding and subsequent overweight were associated with asthma.

METHODS

A nested case-control study included 246 children with pediatric allergist-diagnosed asthma and 477 controls without asthma at age 8 to 10 years. Information on exclusive breast-feeding was obtained from questionnaire data. Overweight at 8 to 10 years of age was defined as body mass index >/=85th percentile of age and sex-specific growth charts. The association between asthma and exclusive breast-feeding <12 weeks plus overweight, adjusted for sex, parental asthma, aboriginal origin, passive smoking at birth, residence location, and family income, was determined in logistic regression analyses.

RESULTS

Exclusive breast-feeding <12 weeks was closely associated with overweight at age 8 to 10 years (P < .001). Exclusive breast-feeding <12 weeks plus overweight was significantly associated with asthma (adjusted OR, 1.81; 95% CI, 1.11-2.95; P = .018). This association appeared to be strong in children whose mothers had asthma (adjusted OR, 3.93; 95% CI, 1.17-13.2) and also in boys (adjusted OR, 2.22; 95% CI, 1.14-4.34). Asthma was not associated with either exclusive breast-feeding <12 weeks or overweight in the absence of the other.

CONCLUSION

Short duration of exclusive breast-feeding and subsequent overweight are associated with asthma in susceptible children, suggesting a common pathway.

CLINICAL IMPLICATIONS

This finding adds to the importance of promoting prolonged breast-feeding for the prevention of overweight and asthma.

Is being breastfed as an infant associated with adult pulmonary function?

OBJECTIVE

Breastfeeding reduces the risk of asthma and respiratory infections in infants. Since respiratory infections are associated with reduced pulmonary function in adolescents, pulmonary function impairment may be carried into adulthood. Our aim was to determine whether a history of having been breastfed as an infant is a determinant of adult pulmonary function.

METHODS

We analyzed data from a general population sample of residents of Erie and Niagara Counties between September 1995 and December 1999. We calculated forced expiratory volume in one second (FEV(1)) and forced vital capacity (FVC) prediction equations and used multiple linear regression models to study the association between having been breastfed as an infant and percentage predicted FEV(1) (FEV(1)%) and percentage predicted FVC (FVC%) after adjustment for covariates.

RESULTS

Of 2305 subjects, 62% reported having been breastfed. After controlling for age, gender, weight, smoking status, pack-years of smoking, eosinophil counts and dietary factors, there was no association between having been breastfed (yes/no) and FEV(1)% or FVC% (regression coefficients 0.0049, p = 0.46 and 0.0055, p = 0.43, respectively).

CONCLUSIONS

We did not find a strong or consistent association between having been breastfed as an infant and pulmonary function in adulthood.

Support for 2 variants of eczema

BACKGROUND

Studies investigating the natural history and risk factors for eczema have historically considered eczema as a single entity, without regard for the individual's atopic status. The association between atopy and eczema is complex, and as many as (2/3) of patients with eczema are not atopic.

OBJECTIVE

To investigate the risk factors for eczema in relation to the child's atopic status in a cohort of high-risk children.

METHODS

A prospective birth cohort of 263 children was followed for 5 years and closely examined for eczema. Antenatal and postnatal data on environmental exposures were collected by interview. Skin prick test to define atopic status was performed at 6 months and 2 and 5 years of age.

RESULTS

Of the subjects, 66.1% had eczema in the first 5 years, and the majority (85.5%) reported onset of rash in the first year. A third of those with eczema were not atopic (nonatopic/intrinsic eczema). Children with atopic eczema (extrinsic eczema) were more likely to be male, to have been breast-fed longer, and to have a history of food allergies, allergic rhinitis, and current wheeze. Nonatopic eczema was more common in girls, and an association was found with early daycare attendance.

CONCLUSION

This study supports the presence of 2 variants of eczema: atopic eczema occurring early in childhood and nonatopic eczema with early daycare attendance. It is likely that environmental factors have a different effect on these 2 variants of eczema, and future studies should thus consider eczema as 2 variants in determining the effect of attributable risks.

Primary prevention of allergy and asthma is possible

Allergic diseases, such as asthma, are the result of complex gene-environment interactions. The focus for prevention of allergic disease has been on environmental control. Environmental exposures begin during the intrauterine period, during which a T-helper-2 immune phenotype is promoted. Food allergy frequently occurs during the first year of life, and avoidance of exposure must begin in early pregnancy and must be complete to be effective. Partial avoidance strategies have not been successful. Current data do not allow us to specifically recommend breastfeeding for the prevention of allergy and allergic diseases, but for other important reasons, breastfeeding (particularly exclusive breastfeeding) should be encouraged for at least the first 4 mo of life. Sensitization to allergens is one of the strongest determinants for subsequent development of asthma. There is a strong relationship between exposure to house dust mites, allergen sensitization, and asthma. However, exposure to pets and animals in a farming environment early in life may actually be protective for the development of allergy and asthma. Specific recommendations relating to these exposures requires additional research, but genetics clearly plays an important role in that process. To date, only a multifaceted intervention program has been successful as a primary prevention strategy for the development of asthma in young children. The specific components of the multifaceted intervention and the duration of protection have not yet been defined. It is increasingly clear that gene-directed environmental manipulation undertaken in a multifaceted manner during a "window of opportunity" is critical in the primary prevention of allergy and allergic diseases like asthma.

Do risk factors for childhood infections and malnutrition protect against asthma? A study of Brazilian male adolescents

OBJECTIVES

We studied the association between early life conditions and asthma in adolescence.

METHODS

We conducted a population-based birth cohort study involving 2250 male 18-year-olds residing in Brazil.

RESULTS

Approximately 18% of the adolescents reported having asthma. Several childhood factors were found to be significantly associated with increased asthma risk: being of high socioeconomic status, living in an uncrowded household, and children being breastfed for 9 months or longer.

CONCLUSIONS

The present results are consistent with the "hygiene hypothesis," according to which early exposure to infections provides protection against asthma. The policy implications of our findings are unclear given that risk factors for asthma protect against serious childhood diseases in developing countries.

Weaning of infants

The WHO 2001 global recommendation is a one size fits all approach to weaning, an approach which may not take sufficient account of the special needs of some infants and fails to allow for the different problems encountered in the industrialised nations compared with economically developing countries. For the healthy normal birth weight full term infant born in an industrialised country, current research supports the benefit of exclusive breast milk feeding until 4-6 months. Evidence of harm through introducing solid food to these infants earlier than this is weak. Infants should be managed individually according to their needs.

Breastfeeding and the prevalence of symptoms of allergic disorders in Japanese adolescents

BACKGROUND

Environmental factors acting early in life are key determinants of the incidence of allergic disease. Whether breastfeeding is protective against allergic disorders remains controversial.

OBJECTIVE

The present cross-sectional study examined the relationship between feeding patterns in the first 3 months of life and the prevalence of symptoms of wheeze, atopic eczema, and rhinoconjunctivitis during the past 12 months in Japanese adolescents.

METHODS

The subjects were 5614 of 9008 students (62%) aged 12-15 years from all public junior high schools in Suita, Japan in 2001. This study used the diagnostic criteria of the International Study of Asthma and Allergies in Childhood. Adjustment was made for gender, grade, number of older siblings, and parental history of allergy.

RESULTS

Feeding pattern was unrelated to the prevalence of wheeze or rhinoconjunctivitis. The prevalence of atopic eczema was significantly higher in children who had been breastfed than in artificial milk feeders (adjusted odds ratios = 1.40 and 1.56, 95% confidence intervals: 1.01-1.98 and 1.13-2.22 for mixed milk intake and breastfeeding only vs. artificial milk consumption, respectively; P = 0.01 for linear trend). When children were divided according to a positive or negative allergic history in at least one parent, an increased prevalence of atopic eczema associated with breastfeeding was found in children with a negative parental allergic history compared with those with a positive parental allergic history.

CONCLUSION

The findings suggest that breastfeeding may be associated with an increased prevalence of atopic eczema, especially among children without a parental history of allergy.

Family history as a predictor of asthma risk

Asthma, one of the most important chronic diseases of children, disproportionately affects minority and low-income children. Many environmental risk factors for asthma have been identified, including animal, mite, and other allergens; cigarette smoke; and air pollutants. Genetics also play an important causative role, as indicated by familial aggregation and the identification of candidate genes and chromosomal regions linked to asthma risk. Using a positive family history of asthma to identify children at increased risk could provide a basis for targeted prevention efforts, aimed at reducing exposure to environmental risk factors. To assess the predictive value of family history as an indicator of risk for childhood asthma, we reviewed population-based studies that evaluated family history of asthma and atopic disease in children with asthma. Our search identified 33 studies from all geographic regions of the world for review. The studies varied in definitions of positive family history and asthma phenotype and used study populations with asthma prevalence ranging from 2% to 26%. Nevertheless, family history of asthma in one or more first-degree relatives was consistently identified as a risk factor for asthma. In ten studies, sensitivity and predictive value of a positive family history of asthma could be calculated: sensitivity ranged from 4% to 43%, positive predictive value from 11% to 37%, and negative predictive value from 86% to 97%. Although a positive family history predicts an increased risk of asthma, it identifies a minority of children at risk. Positive family history may have utility in targeting some individual prevention efforts, but the low positive predictive value limits its value as a means to direct environmental remediation efforts.