Impact of adolescence and gender on asthma hospitalization: a population-based birth cohort study

Sex Disparities in Asthma Development and Clinical Outcomes: Implications for Treatment Strategies

A gender-related disparity exists in asthma morbidity and mortality, which shifts at around puberty from a male predominance to a female predominance. This is clinically reflected in the fact that asthma that occurs in childhood (childhood-onset asthma) mainly affects boys, and that asthma that occurs in adulthood (adult-onset asthma) mainly affects women. Adult-onset asthma is often non-atopic, more severe, and associated with a poorer prognosis, thus posing a marked burden to women’s health and healthcare system. Many factors have been indicated to explain this gender-related disparity, including sociocultural and environmental factors as well as biological sex differences (genetic, pulmonary and immunological factors). It has long been suggested that sex hormones may be implicated in at least these biological sex differences. Overall, the evidence remains equivocal for the role of most sex hormones in asthma pathogenesis and clinical outcomes. Well-designed randomized clinical trials are required assessing the potential preventive or therapeutic effects of hormonal contraceptives on asthma in women, thereby helping to advance the evidence to inform future practice guidelines. The mechanisms underlying the role of sex hormones in asthma are complex, and our understanding is not yet complete. Additional mechanistic studies elucidating sex hormone signaling pathways and their interactions involved in the pathogenesis and clinical manifestations of asthma will help to identify potential sex hormone-driven asthma endotypes and novel therapeutic targets, providing the basis for a more personalized asthma management strategy.

The Human Microbiome, an Emerging Key-Player in the Sex Gap in Respiratory Diseases

The sex gap is well-documented in respiratory diseases such as cystic fibrosis and chronic obstructive pulmonary disease. While the differences between males and females in prevalence, severity and prognosis are well-established, the pathophysiology of the sex difference has been poorly characterized to date. Over the past 10 years, metagenomics-based studies have revealed the presence of a resident microbiome in the respiratory tract and its central role in respiratory disease. The lung microbiome is associated with host immune response and health outcomes in both animal models and patient cohorts. The study of the lung microbiome is therefore an interesting new avenue to explore in order to understand the sex gap observed in respiratory diseases. Another important parameter to consider is the gut-lung axis, since the gut microbiome plays a crucial role in distant immune modulation in respiratory diseases, and an intestinal “microgenderome” has been reported: i.e., sexual dimorphism in the gut microbiome. The microgenderome provides new pathophysiological clues, as it defines the interactions between microbiome, sex hormones, immunity and disease susceptibility. As research on the microbiome is increasing in volume and scope, the objective of this review was to describe the state-of-the-art on the sex gap in respiratory medicine (acute pulmonary infection and chronic lung disease) in the light of the microbiome, including evidence of local (lung) or distant (gut) contributions to the pathophysiology of these diseases.

Associations between prenatal exposure to DDT and DDE and allergy symptoms and diagnoses in the Venda Health Examination of Mothers, Babies and their Environment (VHEMBE), South Africa

Dichlorodiphenyl trichloroethane (DDT) is an organochlorine insecticide that is banned internationally except for use as part of Indoor Residual Spraying (IRS) programs to control malaria. Although animal studies show that DDT and its breakdown product dichlorodiphenyl dichloroethylene (DDE) affect the immune system and may cause allergies, no studies have examined this question in populations where IRS is conducted. The aim of our study was to investigate whether prenatal exposure to DDT and DDE is associated with allergy symptoms and diagnose among South African children living in an area where IRS is conducted. To accomplish this aim, we used data from the Venda Health Examination of Mothers, Babies and their Environment (VHEMBE), an ongoing birth cohort study of 752 children born between 2012 and 2013 in the rural Vhembe district of Limpopo, South Africa. We measured maternal peripartum serum concentrations of DDT and DDE, and administered a questionnaire to the caregivers of 658 children aged 3.5 years to collect information on allergy symptoms and diagnoses as well as potential confounders using validated instruments. Using multiple logistic regression models, we found positive associations between DDT and DDE serum concentrations and most of the allergy symptoms and diagnoses. Maternal DDT (Odds Ratio [OR] = 1.5 per 10-fold increase, 95% Confidence interval, CI = 1.0, 2.3) and DDE (OR = 1.4, 95% CI = 0.8, 2.4) serum concentrations were most strongly associated with caregiver report of wheezing or whistling in the chest. Concentrations of DDT and/or DDE were also associated with increased odds of children's chests sounding wheezy during or after exercise, itchy rashes coming and going for at least six months, diagnosis of food allergy, and diagnosis of dust or dust mites allergy but confidence intervals crossed the null. Results suggest that prenatal exposure to DDT, and possibly DDE, is associated with elevated odds of wheezing among children from an IRS area.

Birth weight and prematurity with lung function at ~17.5 years: "Children of 1997" birth cohort

We aimed to determine if prematurity and lower birth weight are associated with poorer lung function in a non-western developed setting with less marked confounding by socioeconomic position. Using multivariable linear regression in Hong Kong’s “Children of 1997” birth cohort, adjusted associations of prematurity and birth weight with forced expiratory volume in 1 second (FEV₁), forced vital capacity (FVC), and forced expiratory flow at 25–75% of the pulmonary volume (FEF_25–75%) at ~17.5 years were assessed. Associations for birth weight were stronger in boys for FEV₁ (boys: 0.31 L, 95% confidence interval (CI) 0.24 to 0.38, girls: 0.18 L, 95% CI 0.12 to 0.25), FVC (boys: 0.36 L, 95% CI 0.27 to 0.44, girls: 0.22 L, 95% CI 0.15 to 0.28) and FEF_25–75% (boys: 0.35 L, 95% CI 0.21 to 0.49, girls: 0.22 L, 95% CI 0.09 to 0.34) adjusted for age, socioeconomic position and infant and maternal characteristics. Similarly adjusted, preterm birth (compared to full-term birth) was associated with lower FEV₁/FVC and FEF_25–75%. Thus, associations of lower birth weight, especially in boys, and prematurity with poorer lung function at 17.5 years were found. Identifying underlying mechanism might contribute to the improvement of pulmonary health and the prevention of adult respiratory illness.

Sex differences in the influence of obesity on a murine model of allergic lung inflammation

BACKGROUND

Despite the overwhelming evidence showing the influence of sex or obesity in the development of respiratory diseases in humans and animals, the mechanisms by which these combined two factors influence allergic asthma are not well understood.

OBJECTIVE

We have investigated the interaction between sex and weight gain in an experimental model of lung allergic inflammation induced by chicken egg ovalbumin (OVA) in mice.

METHODS

Animals were fed a high-fat diet for 8 weeks and then sensitized and challenged with OVA.

RESULTS

Our results demonstrate that in comparison with males, high-fat diet (HFD) allergic female mice exhibit a reduction in the number of leucocytes in the lung lumen when challenged with OVA and, in contrast, an accumulation of these cells in the lung tissue. In addition, we also observed that allergic HFD female mice presented a robust lung remodelling in comparison with HFD males, evidenced by higher deposition of collagen in the airways and TGF-β in lung fluid. Measuring epithelial adhesion molecule expression, we observed that female mice presented a significantly lower expression of CD103 than males in BAL cells, regardless of the diet. Similarly, HFD female mice express lower levels of EpCAM in lung tissue in comparison with males and lean females. Levels of A20/TNFAIP3 expression in lung tissue demonstrated that HFD female mice express lower levels of these regulatory factors than all the other groups. However, this reduction was not accompanied by an increase in activated NF-κB.

CONCLUSIONS

Our results present evidence that the interaction between sex and weight gain alters the progression of allergic asthma in mice with females developing airway remodelling at a much earlier stage than males.

CLINICAL RELEVANCE

These data may contribute to a better understanding of the clinical differences in the development and severity of allergic asthma observed between men and women of reproductive age.

Sex-specific risk factors for childhood wheeze and longitudinal phenotypes of wheeze

BACKGROUND

Although sexual dimorphism in wheeze and asthma prevalence are well documented, sex-specific risk factors for wheeze and longitudinal wheeze phenotypes have not been well elucidated.

OBJECTIVE

By using a large prebirth cohort, this study aimed to identify sex-specific risk factors for wheeze from birth through midchildhood and identify distinct longitudinal wheeze phenotypes and the sex-specific risk factors associated with these phenotypes.

METHODS

Mothers reported child wheeze symptoms over the past year approximately yearly on 9 occasions starting at age 1 year. We identified sex-specific predictors of wheeze, wheeze phenotypes, and sex-specific predictors of these phenotypes by using generalized estimating equations, latent class mixed models, and multinomial logistic analysis, respectively.

RESULTS

A total of 1623 children had information on wheeze at 1 or more time points. Paternal asthma was a stronger predictor of ever wheezing in boys (odds ratio [OR], 2.15; 95% CI, 1.74-2.66) than in girls (OR, 1.53; 95% CI, 1.19-1.96; P for sex by paternal asthma interaction = .03), whereas being black or Hispanic, birth weight for gestational age z score, and breast-feeding duration had stronger associations among girls. We identified 3 longitudinal wheeze phenotypes: never/infrequent wheeze (74.1%), early transient wheeze (12.7%), and persistent wheeze (13.1%). Compared with never/infrequent wheeze, maternal asthma, infant bronchiolitis, and atopic dermatitis were associated with persistent wheeze in both sexes, but paternal asthma was associated with persistent wheeze in boys only (OR, 4.27; 95% CI, 2.33-7.83; P for sex by paternal asthma interaction = .02), whereas being black or Hispanic was a predictor for girls only.

CONCLUSION

We identified sex-specific predictors of wheeze and longitudinal wheeze patterns, which might have important prognostic value and allow for a more personalized approach to wheeze and asthma treatment.

Asthma as a disruption in iron homeostasis

Over several decades, asthma has evolved from being recognized as a single disease to include a diverse group of phenotypes with dissimilar natural histories, pathophysiologies, responses to treatment, and distinctive molecular pathways. With the application of Occam's razor to asthma, it is proposed that there is one cause underlying the numerous phenotypes of this disease and that the responsible molecular pathway is a deficiency of iron in the lung tissues. This deficiency can be either absolute (e.g. asthma in the neonate and during both pregnancy and menstruation) or functional (e.g. asthma associated with infections, smoking, and obesity). Comparable associations between asthma co-morbidity (e.g. eczema, urticaria, restless leg syndrome, and pulmonary hypertension) with iron deficiency support such a shared mechanistic pathway. Therapies directed at asthma demonstrate a capacity to impact iron homeostasis, further strengthening the relationship. Finally, pathophysiologic events producing asthma, including inflammation, increases in Th2 cells, and muscle contraction, can correlate with iron availability. Recognition of a potential association between asthma and an absolute and/or functional iron deficiency suggests specific therapeutic interventions including inhaled iron.

Gender- and age-specific risk factors for wheeze from birth through adolescence

BACKGROUND AND OBJECTIVE

Cross-sectional gender differences in wheeze are well documented, but few studies have examined the gender-specific risk factors for wheeze longitudinally. This study aims to identify gender- and age-specific risk factors for wheeze from birth through adolescence.

METHODS

The incidence of wheeze was ascertained every 6 months through age 14 years in a birth cohort consisting of 499 children with a parental history of atopy. Gender- and age-specific risk factors were identified through generalized estimating equations.

RESULTS

A total of 454 (91.0%) and 351 (70.3%) children were followed past age 7 and 13 years, respectively. Maternal asthma was a risk factor for wheeze in girls (OR = 2.05, 95% CI 1.44-2.91, P < 0.0001) and boys (OR = 1.79, 1.29-2.48, P = 0.0004) and had a similar effect on wheeze throughout the ages. Paternal asthma (OR = 1.83, 1.38-2.57, P = 0.0005) and infant bronchiolitis (OR = 2.15, 1.47-3.14, P < 0.0001) were risk factors for boys only, with similar effects throughout the ages.

CONCLUSION

Using a prospective cohort, we identified gender- and age-specific risk factors for wheeze. The identification of gender-specific early life risk factors may allow for timely interventions and a more personalized approach to the treatment of asthma.

Tailoring interventions: identifying predictors of poor asthma control

BACKGROUND

Determining the factors that will predict long-term asthma control is essential for improving health outcomes and decreasing the burden on the health care system. Patient-reported outcomes (PROs) on health behaviors can provide valuable information about future asthma control but have rarely been considered in previous analyses.

OBJECTIVE

To develop statistical models for evaluating the predictors of long-term asthma control using PROs such as scores of the Asthma Control Test and the Asthma Self-Efficacy Scale.

METHODS

Of 1,437 individuals contacted, 566 (39%) at baseline and 486 (34%) at follow-up completed the questionnaires, including 4 PROs (Asthma Control Test, Asthma Self-Efficacy Scale, Mini-Asthma Quality of Life Questionnaire, and Beliefs about Medication Questionnaire). Long-term asthma control was evaluated by assessing overuse of rescue medication and emergency department visits. A multivariate logistic generalized estimating equation model was fitted to evaluate the possible effect of the studied factors on asthma control.

RESULTS

The complete case generalized estimating equation analysis included 286 participants who had complete PROs at the 2 evaluation times. After adjusting for socioeconomic status and smoking status, the Mini-Asthma Quality of Life Questionnaire was a significant predictor of asthma exacerbation. For each 1-point increase on the Mini-Asthma Quality of Life Questionnaire, there was a 0.25 decrease in the odds of a patient's asthma getting out of control.

CONCLUSION

These findings suggest opportunities to decrease the burden on health care by tailoring interventions that combine PROs with other clinical and sociodemographic variables.

Natural progression of childhood asthma symptoms and strong influence of sex and puberty

RATIONALE

Asthma prevalence, onset, remission and relapse, and healthcare use have been intensively studied. However, asthma symptom progression through childhood and adolescence has not been well studied, in part due to the challenges in obtaining consistent and robust long-term follow-up data on a large series of subjects with asthma.

OBJECTIVES

To use the asthma diary symptom data of the Childhood Asthma Management Program placebo group (5 yr, 418 subjects, and total 564,518 records) to establish sex-specific high-resolution time courses of the natural progression of asthma symptoms through childhood and adolescence.

METHODS

We used the asthma diary symptom code as a measure of daily disease severity. Annual records of Tanner stage were used to determine the influence of puberty on severity. A data alignment technique was used to derive 13-year time courses of mean symptoms and mean Tanner stage.

MEASUREMENTS AND MAIN RESULTS

Data analyses showed three age- and sex-related phases of asthma symptom progression: Phase 1 (ages 5 and 6 yr)-greater severity in boys; Phase 2 (ages 7 to 9 yr)-no sex difference in severity; and Phase 3 (age 10-17 yr)-greater severity in girls. The continuous decline of symptoms in both sexes stops abruptly at the onset of puberty.

CONCLUSIONS

The severity of asthma symptoms varies through childhood and adolescence, and patterns differ by sex. Puberty has a strong influence on symptom progression in both sexes. Progression of symptoms is a distinct aspect of asthma epidemiology.

The adolescent with asthma

The adolescent with asthma experiences a period of physical and psychosocial changes that affect their health and well-being. Overall, adolescents with asthma are at increased risk for asthma morbidity and death. Increased rates of depression and anxiety, for the adolescent and their caregivers, can lead to non-adherence to their medical regimens, poor symptom control, and poor treatment outcomes. Contextual factors, such as race, ethnicity, and living situation, affect the prevalence, morbidity, and mortality for the adolescent with asthma. These factors also affect the transition process for adolescents entering adult medical care. An overview is presented of how the adolescent with asthma differs and how healthcare providers can promote effective asthma management and better asthma control.

Factors related with the higher percentage of hospitalizations due to asthma amongst women: the FRIAM study

INTRODUCTION

The reason why there is a higher hospitalization rate due to asthma exacerbations amongst women is unclear. The objective of this study is to explore the possible causes that may explain this fact.

METHODS

A multi-center, prospective study including asthma patients hospitalized in the pulmonary medicine departments during a two-year period. By means of a questionnaire, the following data were collected: demographic characteristics and treatment compliance, anxiety-depression, hyperventilation and asthma control, both prior to and during the hospitalization.

RESULTS

183 patients were included, 115 (62.84%) of whom were women. The women were older (52.4 ± 18.3/43.4 ± 18.7; P=.02), were more frequently prescribed inhaled corticosteroids (63.2%/47.1%; P=.03) and had a higher rate of hyperventilation syndrome (57.3/35.9; P=.02) and a longer mean hospital stay (7.3 ± 3.4/5.9 ± 3.6; P=.02). The percentage of smokers among the women was lower (21.2%/38.8%; p=0.01) and the FEV(1) was lower at admittance (58.2% ± 15.9/67.5% ± 17.4; P=.03). In the 40 to 60-year-old age range, an association was demonstrated between being female and the 'previous hospitalizations' variable (OR, 16.1; 95% CI, 1.6-156.7); sex and obesity were also independently associated (OR, 4.8; 95% CI, 1.06-22).

CONCLUSIONS

In this cohort, the rate of hospitalization for asthma was higher in women than in men. Being a woman between the ages of 40 and 60 is associated with previous hospitalizations and is a risk factor for asthma-related hospitalization. This situation could partially be explained by the hormonal changes during menopause, where polyposis and obesity are independent risk factors.

Development and validation of a predictive algorithm to identify adult asthmatics from medical services and pharmacy claims databases

OBJECTIVE

To develop and validate the accuracy of a predictive model to identify adult asthmatics from administrative health care databases.

STUDY SETTING

An existing electronic medical record project in Montreal, Quebec.

STUDY DESIGN

One thousand four hundred and thirty-one patients with confirmed asthma status were identified from primary care physician's electronic medical record.

DATA COLLECTION/EXTRACTION METHODS

Therapeutic indication of asthma in an electronic prescription and/or confirmed asthma from an automated problem list were used as the gold standard. Five groups of asthma-specific markers were identified from administrative health care databases to estimate the probability of the presence of asthma. Cross-validation evaluated the diagnostic ability of each predictive model using 50 percent of sample.

PRINCIPAL FINDINGS

The best performance in discriminating between the patients with asthma and those without it included indicators from medical service and prescription claims databases. The best-fitting algorithm had a sensitivity of 70 percent, a specificity of 94 percent, and positive predictive value of 65 percent. The prescriptions claims-specific algorithm demonstrated a nearly equal performance to the model with medical services and prescription claims combined.

CONCLUSIONS

Our algorithm using asthma-specific markers from administrative claims databases provided moderate sensitivity and high specificity.

Prevalence and geographic variations in asthma symptoms in children and adolescents in Galicia (Spain)

OBJECTIVES

To determine the prevalence and geographic variations of the symptoms associated with asthma in Galician children and adolescents.

POPULATION AND METHODS

A cross-sectional epidemiological study following ISAAC (International Study of Asthma and Allergies in Childhood) methodology, and using a written questionnaire distributed in schools. The study sample included 10,371 6-7 year-old children and 10,372 13-14 year-old adolescents, all of them from Galician Health Areas. A logistic regression model was used to analyse geographic variations.

RESULTS

In the 6-7 year-old group, wheezing in the last 12 months varied from 11.4% (Santiago) to 15.7% (Vigo) and in the adolescents varied from 8.8% (Ourense) to 18.8% (Vigo). The distribution by gender showed a predominant significance in 6-7 year-old males (P<.001), and near to be statistically significant in 13-14 year-old females (P=.08). The risk (odds ratio [OR]) of wheezing in the last 12 months in the area with highest prevalence in comparison with the area of lowest prevalence was 1.45 (95% Confidence Interval [CI], 1.12-1.88) for children and 2.39 (95% CI, 1.82-3.13) for adolescents. The estimated prevalence of asthma in the Autonomous Community of Galicia was 13.6% in younger children and 12.2% in adolescents.

CONCLUSIONS

The prevalence of wheezing in the last 12 months in the different areas of Galicia is considerably higher than the rest of Spanish ISAAC cities in the 6-7 years group and very similar in the 13-14 years group, except in Vigo where it is considerably higher. We found a clearly defined geographic pattern in the adolescent group, with higher prevalences in coastal areas than in the interior.

Inorganic arsenite inhibits IgE receptor-mediated degranulation of mast cells

Millions of people worldwide are exposed to arsenic (As), a toxicant which increases the risk of various cancers, cardiovascular disease and several other health problems. Arsenic is a potent endocrine disruptor, including of the estrogen receptor. It was recently shown that environmental estrogen-receptor disruptors can affect the signaling of mast cells, which are important players in parasite defense, asthma and allergy. Antigen (Ag) or allergen crosslinking of IgE-bound receptors on mast cells leads to signaling, culminating in degranulation, the release of histamine and other mediators. Because As is an endocrine disruptor and because endocrine disruptors have been found to affect degranulation, here we have tested whether sodium arsenite affects degranulation. Using the rat basophilic leukemia (RBL) mast cell model, we have measured degranulation in a fluorescence assay. Arsenic alone had no effect on basal levels of degranulation. However, As strongly inhibited Ag-stimulated degranulation at environmentally relevant concentrations, in a manner that is very dependent on concentrations of both As and Ag. The concentrations of As effective at inhibiting degranulation were not cytotoxic. This inhibition may be a mechanism underlying the traditional Chinese medicinal use of As to treat asthma. These data indicate that As may inhibit the ability of humans to fight off parasitic disease.

The association between community crime and childhood asthma prevalence in Chicago

BACKGROUND

Little attention has been given to exposure to crime as a possible socioenvironmental contributor to variability in urban childhood asthma prevalence.

OBJECTIVE

To determine the association of violent crime, property crime, and drug abuse violations with childhood asthma prevalence in Chicago.

METHODS

In 2003-2005, the Chicago Initiative to Raise Asthma Health Equity conducted an asthma screening survey of children in grades K to 8 attending Chicago public and Catholic schools. Crime data were obtained from the Chicago Police Department. In addition to simple regression analysis, multilevel logistic regression analysis was performed to estimate the effect of criminal activity on neighborhood asthma variance.

RESULTS

Of the surveys returned, 45,371 (93%) were geocoded into 247 neighborhoods. Neighborhoods were divided into quartile groups by mean asthma prevalence (9%, 12%, 17%, and 22%). Criminal activity (annual incidence per 100,000 people) was significantly higher (P < .001) in neighborhoods with a high asthma prevalence, especially drug abuse violations, which increased more than 6-fold (461 vs 2,921), and violent crimes, which increased more than 3-fold (448 vs 1,566). After adjusting for community race/ethnicity, only violent crime continued to be significantly associated with the neighborhood asthma prevalence (odds ratio, 1.27; 95% confidence interval, 1.04-1.55, P < .05). When considered alongside sociodemographic and individual characteristics, violence continued to contribute significantly (P < .05), explaining 15% of neighborhood variation in childhood asthma.

CONCLUSIONS

Evidence suggests an association between violent crime and childhood asthma prevalence in Chicago. A deeper understanding of the mechanisms that underlie this association may lend insight into potential interventions to address urban asthma.

Patterns of inhaled corticosteroid use and asthma control in the Childhood Asthma Management Program Continuation Study

BACKGROUND

Daily controller medication use is recommended for children with persistent asthma to achieve asthma control.

OBJECTIVE

To examine patterns of inhaled corticosteroid (ICS) use and asthma control in an observational study of children and adolescents with mild-to-moderate asthma (the Childhood Asthma Management Program Continuation Study).

METHODS

We assessed patterns of ICS use during a 12-month period (consistent, intermittent, and none) and asthma control (well controlled vs poorly controlled). Multivariate logistic regression examined the association between pattern of ICS use and asthma control.

RESULTS

Of 914 patients enrolled, 425 were recommended to continue receiving ICS therapy in the Childhood Asthma Management Program Continuation Study. Of these patients, 46% reported consistent ICS use and 20% reported no ICS use during year 1. By year 4, consistent ICS use decreased to 20%, whereas no ICS use increased to 57%; poorly controlled asthma was reported in 18% of encounters. In multivariate models controlling for age, sex, forced expiratory volume in 1 second, and asthma severity assessment, patients reporting consistent ICS use during a 12-month period were more likely to report poor asthma control (odds ratio, 1.6; 95% confidence interval, 1.2-2.1) compared with those reporting no ICS use.

CONCLUSIONS

In this observational study of children and adolescents with mild-to-moderate asthma, most did not report continued use of ICS. Patients recommended to continue receiving ICS therapy and reporting consistent ICS use were less likely to report well-controlled asthma even after controlling for markers of asthma severity. Although residual confounding by severity cannot be ruled out, many children and adolescents may not achieve well-controlled asthma despite consistent use of ICS.

The protective effect of community factors on childhood asthma

BACKGROUND

Asthma burden in the US is not evenly distributed. Although asthma prevalence varies widely across urban neighborhoods, little attention has been paid to the community as a key contributor.

OBJECTIVE

To determine the effect of positive socio-environmental community factors on childhood asthma prevalence in Chicago.

METHODS

From 2003 to 2005, an asthma screening survey was conducted among children attending Chicago Public/Catholic schools from kindergarten through eighth grade. One hundred five schools participated, yielding a stratified representation of 4 race-income groups. Positive community factors, such as social capital, economic potential, and community amenities, were assessed by using the Metro Chicago Information Center's Community Vitality Index.

RESULTS

Of the surveys returned, 45,177 (92%) were geocoded into 287 neighborhoods. Neighborhoods were divided into quartile groups by asthma prevalence (mean, 8%, 12%, 17%, 25%). Community vitality (54% vs 44%; P < .0001) and economic potential (64% vs 38%; P < .0001) were significantly higher in neighborhoods with low asthma prevalence. Neighborhood interaction (36% vs 73%; P < .0001) and stability (40% vs 53%; P < .0001) were significantly higher in neighborhoods with high asthma prevalence. Overall, positive factors explained 21% of asthma variation. Childhood asthma increased as the black population increased in a community (P < .0001). Accordingly, race/ethnicity was controlled. In black neighborhoods, these factors remained significantly higher in neighborhoods with low asthma prevalence. When considered alongside socio-demographic/individual characteristics, overall community vitality as well as social capital continued to contribute significantly to asthma variation.

CONCLUSION

Asthma prevalence in Chicago is strongly associated with socio-environmental factors thought to enrich a community. A deeper understanding of this impact may lend insight into interventions to reduce childhood asthma.

Gender differences in the prevalence of airway hyperresponsiveness and asthma in athletes

BACKGROUND

Although athletes have a high prevalence of airway hyperresponsiveness (AHR) and asthma, little is known about possible gender differences in regard to these features. We looked at the comparative prevalence of AHR, physician-diagnosed asthma and respiratory symptoms during exercise in female (F) and male (M) athletes.

METHOD

A retrospective analysis was done on 2 groups of athletes: Group 1 (n=100) taking part in a study on the prevalence of AHR to methacholine (PC(20)<16mg/ml) and Group 2 (n=698), taking part in a provincial survey on the prevalence of physician-diagnosed asthma. Subjects from both groups filled the same questionnaire on respiratory symptoms during exercise (breathlessness, wheezing and chest tightness).

RESULTS

In Group 1, prevalence of AHR was significantly higher in female (60%) compared with male (21.5%, p<0.0001) athletes despite a similar prevalence of physician-diagnosed asthma (F: 17.1%, M: 15.4%, p>0.05). Respiratory symptoms during exercise were more frequently reported in females (37.1%, M: 16.9%, p=0.02); however, when corrected for the PC(20), this difference became non-significant. In Group 2, the prevalence of physician-diagnosed asthma was not different between genders (F: 12.5%, M: 14%, p>0.05) but respiratory symptoms during exercise were more often reported in female (19.4%) than in male (12.2%, p=0.01) athletes.

CONCLUSIONS

This analysis shows a higher prevalence of AHR and exercise-induced respiratory symptoms in female compared to male athletes, but a similar prevalence of physician-diagnosed asthma. This suggested that the increase in respiratory symptoms in female athletes failed to translate into a higher prevalence of physician-diagnosed asthma.

Geographic variability in childhood asthma prevalence in Chicago

BACKGROUND

Childhood asthma prevalence has been shown to be higher in urban communities overall without an understanding of differences by neighborhood.

OBJECTIVE

To characterize the geographic variability of childhood asthma prevalence among neighborhoods in Chicago.

METHODS

Asthma screening was conducted among children attending 105 Chicago schools as part of the Chicago Initiative to Raise Asthma Health Equity. Additional child information included age, sex, race/ethnicity, and household members with asthma. Surveys were geocoded and linked with neighborhoods. Neighborhood information on race, education, and income was based on 2000 census data. Bivariate and multilevel analyses were performed.

RESULTS

Of the 48,917 surveys, 41,255 (84.3%) were geocoded into 287 neighborhoods. Asthma prevalence among all children was 12.9%. Asthma rates varied among neighborhoods from 0% to 44% (interquartile range, 8% to 24%). Asthma prevalence (mean, SD, range) in predominantly black neighborhoods (19.9, +/-7, 4% to 44%) was higher than in predominantly white neighborhoods (11.4, +/-4.7, 2% to 30%) and predominantly Hispanic neighborhoods (12.1, +/-6.8, 0% to 29%). Although sex, age, household members with asthma, and neighborhood income significantly affected asthma prevalence, they did not explain the differences seen between neighborhoods. Race explained a significant proportion (about 80%) but not all of this variation.

CONCLUSION

Childhood asthma prevalence varies widely by neighborhood within this urban environment. Adjacent areas in Chicago were identified with significantly different asthma prevalence. A better understanding of the effect of neighborhood characteristics may lend insight into potential interventions to reduce childhood asthma.

Impact of gender on asthma in childhood and adolescence: a GA2LEN review

A number of studies have shown gender differences in the prevalence of wheeze and asthma. The aim of this review was to examine published results on gender differences in childhood and adolescent asthma incidence and prevalence, define current concepts and to identify new research needs. A Medline search was performed with the search words (gender OR sex) AND (child OR childhood OR adolescence) AND (asthma). Articles that reported on absence or presence of gender differences in asthma were included and reviewed, and cross-references were checked. Boys are consistently reported to have more prevalent wheeze and asthma than girls. In adolescence, the pattern changes and onset of wheeze is more prevalent in females than males. Asthma, after childhood, is more severe in females than in males, and is underdiagnosed and undertreated in female adolescents. Possible explanations for this switch around puberty in the gender susceptibility to develop asthma include hormonal changes and gender-specific differences in environmental exposures. This aspect needs consideration of the doctors and allergists who diagnose and treat asthmatic individuals. In conclusion, sex hormones are likely to play an important role in the development and outcome of the allergic immune response and asthma in particular. By obtaining functional data from appropriate models, the exact underlying mechanisms can be unravelled. To examine the effect of gender-specific differences in environmental exposures and changes of asthma prevalence and severity in puberty, larger populations may need to be investigated.

Role of sex hormones in allergic inflammation in mice

BACKGROUND

A number of clinical studies have documented both a pro- and anti-inflammatory role for sex hormones in the context of lung inflammation and worsening of asthma.

OBJECTIVE

To determine the role of sex hormones in a murine model of allergic inflammation and airway hyper-responsiveness (AHR) induced by ovalbumin (OVA).

METHODS

Female BALB/c were sensitized to OVA on days 0 and 7 and subsequently challenged on day 14 over a 3-day period. Mice had their ovaries removed either 7 days before or 8 days after the first OVA injection on day 0. Pulmonary eosinophilia and AHR were measured 24 h following the last antigen challenge. In other experiments, ovariectomized mice (Ovx) were pre-treated with oestradiol benzoate. In further studies, the effect of the oestradiol antagonist tamoxifen on allergic inflammation in intact mice was evaluated. Spleens from all groups were collected for proliferation assays and measurement of cytokine release.

RESULTS

Removal of the ovaries 7 days before sensitization to OVA significantly inhibited lung eosinophilia and IL-5 levels in lung lavage. Furthermore, airway reactivity (maximum response) but not sensitivity (PC100) to methacholine were significantly reduced in these mice. Proliferation of spleen cells and release of IL-5 collected from Ovx mice was significantly attenuated compared with spleen cells obtained from non-Ovx mice. Ovx mice treated with oestradiol benzoate presented partially restored levels of eosinophils and IL-5 in sensitized mice. Moreover, pharmacological antagonism of the effect of endogenous oestrogen with tamoxifen significantly reduced the number of eosinophils in the lung of intact sensitized mice, reproducing the effect of ovariectomy, and suggested a role for oestrogen in the process of antigen sensitization in female mice. In contrast, removal of ovaries 8 days after the first OVA injection failed to alter significantly pulmonary eosinophilia or AHR to methacholine in comparison with non-Ovx mice. Moreover, removal of the ovaries 8 days after the sensitization period induced a significant increase in levels of IL-5 in lung fluid. Spleen cells collected from these mice also had a significantly higher proliferation index and production of IL-5 in response to OVA than non-Ovx mice. Treatment with oestradiol benzoate partially reduced levels of eosinophils present in the lung of Ovx mice, supporting an anti-inflammatory role of sex hormones during the effector phase of the response to inhaled antigen.

CONCLUSION

Sex hormones play a dual role in regulating allergic lung inflammation in mice.

Attenuation of the September epidemic of asthma exacerbations in children: a randomized, controlled trial of montelukast added to usual therapy

BACKGROUND

A recurring epidemic of asthma exacerbations in children occurs annually in September in North America when school resumes after summer vacation.

OBJECTIVE

Our goal was to determine whether montelukast, added to usual asthma therapy, would reduce days with worse asthma symptoms and unscheduled physician visits of children during the September epidemic.

PATIENTS AND METHODS

A total of 194 asthmatic children aged 2 to 14 years, stratified according to age group (2-5, 6-9, and 10-14 years) and gender, participated in a double-blind, randomized, placebo-controlled trial of the addition of montelukast to usual asthma therapy between September 1 and October 15, 2005.

RESULTS

Children randomly assigned to receive montelukast experienced a 53% reduction in days with worse asthma symptoms compared with placebo (3.9% vs 8.3%) and a 78% reduction in unscheduled physician visits for asthma (4 [montelukast] vs 18 [placebo] visits). The benefit of montelukast was seen both in those using and not using regular inhaled corticosteroids and among those reporting and not reporting colds during the trial. There were differences in efficacy according to age and gender. Boys aged 2 to 5 years showed greater benefit from montelukast (0.4% vs 8.8% days with worse asthma symptoms) than did older boys, whereas among girls the treatment effect was most evident in 10- to 14-year-olds (4.6% [montelukast] vs 17.0% [placebo]), with nonsignificant effects in younger girls.

CONCLUSIONS

Montelukast added to usual treatment reduced the risk of worsened asthma symptoms and unscheduled physician visits during the predictable annual September asthma epidemic. Treatment-effect differences observed between age and gender groups require additional investigation.

Salivary cotinine, doctor-diagnosed asthma and respiratory symptoms in primary schoolchildren

Due to impaired airway function, children are at risk for adverse respiratory symptoms if exposed to environmental tobacco smoke (ETS). A community-based, cross-sectional study of 425 children (5-11 years) attending 15 primary schools in a low socio-economic area of Merseyside/UK was undertaken to investigate the association of adverse respiratory symptoms and ETS exposure using a parent-completed questionnaire and children's salivary cotinine measurements. Overall, 28.9% of children had doctor-diagnosed asthma (DDA) and 11.3% a history of hospital admission for respiratory illnesses. The symptom triad of cough, wheeze and breathlessness (C+W+B+) occurred in 12.6% of children. The geometric mean cotinine level was 0.37 ng/ml (95% CI, 0.33-0.42 ng/ml) and it was estimated that 45.6% of children were ETS exposed. A history of asthma in the family was reported for 9.2% of fathers and 7.2% of mothers. Salivary cotinine level was significantly increased in children with DDA compared to those without (P = 0.002). Cotinine-validated levels [adjusted odds ratio (AOR), 1.8; 95% CI, 1.4-2.5), low socio-economic (disadvantaged) status (AOR, 1.4; 1.1-2.9), child's male gender (AOR, 1.6; 1.1-2.5) and maternal smoking (AOR, 2.2; 1.4-3.1) were significantly associated with DDA. The cotinine-validated level (AOR, 1.4; 1.1-2.9) as well as maternal smoking (AOR, 1.8; 1.1-2.5), were also independently associated with C+W+B+. The use of salivary cotinine as an indicator of ETS exposure could be used to inform parents of exposure risk to their asthmatic children and may help re-enforce deterrent efforts to reduce childhood parental smoking exposure.

Demographic and clinical characteristics of children and adolescents with severe or difficult-to-treat asthma

BACKGROUND

Young patients with severe or difficult-to-treat asthma are an understudied population.

OBJECTIVE

To assess age-associated and gender-associated differences in children and adolescents in the observational study, The Epidemiology and Natural History of Asthma: Outcomes and Treatment Regimens.

METHODS

Cross-sectional baseline data for patients greater than or equal to 6 years and less than or equal to 17 years (n = 1261) were stratified by age group (6-8, 9-11, 12-14, and 15-17 years). The chi(2) test for categorical variables and analysis of variance for continuous variables were used to identify differences among age groups, stratified by gender.

RESULTS

Most patients had moderate (55%) or severe (41%) asthma by physician assessment. Of those using greater than or equal to 3 long-term controllers (62%), 53% of children (6-11 years) and 44% of adolescents (12-17 years) reported an oral corticosteroid burst and 25% and 19%, respectively, had an emergency department visit in the previous 3 months; 10% and 15%, respectively, reported past intubation. In females, weight for age ranged between the 67th and 70th percentiles; height for age was between the 42nd and 54th percentiles (P < .01 among age groups). Lung function was lower in adolescents than children: prebronchodilator percent predicted forced expiratory volume in 1 second (FEV(1))/forced vital capacity was 0.92 (6-8 years) and 0.83 (15-17 years), P less than .05, in males; and 0.94 (6-8 years) and 0.87 (15-17 years), P less than .05, in females.

CONCLUSIONS

Children and adolescents demonstrated high rates of health care use and loss of lung function, despite using multiple long-term controllers.

CLINICAL IMPLICATIONS

Asthma treatments that prevent loss of lung function and reduce health care resource use are needed in young patients with severe or difficult-to-treat asthma.

Asthma hospitalizations among US military personnel, 1994 to 2004

BACKGROUND

Acute asthma attacks strike unpredictably and may lead to hospitalization in otherwise healthy individuals. The burden of asthma hospitalization on the US health care system has greatly interested health care workers, many of whom see the incidence of asthma as increasing.

OBJECTIVES

To examine the annual incidence of hospitalization and the frequency of subsequent hospitalization for asthma among all active-duty US military personnel between 1994 and 2004 and to determine demographic and occupational risk factors of asthma hospitalization within this generally healthy US population.

METHODS

Annual demographic and occupational data were combined with electronic hospitalization records for patients with a discharge diagnosis of asthma. Using Cox proportional hazard modeling, the authors investigated demographic and occupational risk factors for asthma hospitalization.

RESULTS

Women, married persons, health care workers, enlisted personnel, US Army personnel, and older persons were found to have a significantly greater risk of asthma hospitalization. Yearly rates of hospitalization declined from 22.3 per 100,000 persons to 12.6 per 100,000 persons between 1994 and 2004.

CONCLUSIONS

Although these data have some limitations, they suggest that the burden of asthma hospitalizations in the large, healthy population of US military personnel has declined during the last decade. The decrease in hospitalization potentially reflects improved outpatient management strategies.

Chronic productive cough in school children: prevalence and associations with asthma and environmental tobacco smoke exposure

Background

The relationships between chronic productive cough (CPC), environmental tobacco smoke (ETS) exposure, and asthma are not clearly established in children. Therefore, we wished to determine the prevalence of CPC and examine the relationships between CPC, ETS exposure, and asthma in young teenagers.

Methods

We performed a cross sectional survey of 2397 Seattle middle school students, 11–15 years old, using written and video respiratory-symptom questionnaires. We defined CPC as – daily cough productive of phlegm for at least 3 months out of the year; current asthma as – yes to "Have you had wheezing or whistling in your chest in the past 12 months?" and yes in the past year to any of the four video wheezing/asthma video scenarios; and ETS exposure as exposed to tobacco smoke at least several hours each day. We used multilogistic regression to examine relationships between CPC, asthma, and ETS exposure and included in the model the potentially confounding variables race, gender, and allergic rhinitis.

Results

The prevalence of CPC was 7.2%. Forty-seven percent (82/173) of children with CPC met criteria for current asthma, while only 10% (214/2224) of those without CPC had current asthma. Current asthma had the strongest associated with CPC, odds ratio (OR) 6.4 [95% CI 4.5–9.0], and ETS was independently associated with both CPC, OR 2.7 [1.8–4.1] and asthma, OR 2.7 [1.5–4.7].

Conclusion

In a population of young teenagers, CPC was strongly associated with report of current asthma symptoms and also with ETS exposure. This suggests that asthma and ETS exposure may contribute to CPC in children. However, this study was not designed to determine whether asthma was the actual cause of CPC in this population of children.

Endocrine disrupters--potential modulators of the immune system and allergic response

Endocrine disrupters (EDs) are environmental pollutants of industrial or agricultural origin (e.g. herbicides, fungicides, insecticides, industrial chemicals) that may influence health of wildlife and human. Endocrine-disrupting effect is obtained by mimicking the action of the steroid hormones and has been associated with several reproductive disorders as well as cancerogenesis both in animals and humans. EDs can also influence synthesis of cytokines, immunoglobulins, and cell mediators as well as immune cell activation and survival. Modulation by EDs of interleukin-4 production, Th1/Th2 balance and IgE production suggest their potential effect on allergic immune responses. The aim of this review was to summarize data indicating a potential effect of EDs exposure on the immune system and allergic responses.

Factors influencing gender differences in the diagnosis and treatment of asthma in childhood: the Tucson Children's Respiratory Study

Studies identified gender differences in diagnosed asthma, but the extent to which they can be attributed to differences in symptom experience and frequency rather than factors influencing diagnosis has not been established. We investigated prevalence of, and consultation for, asthma symptoms, as well as diagnosis and treatment in 533 boys and 556 girls enrolled in the Tucson Children's Respiratory Study, a population-based birth-cohort study. Questionnaires regarding respiratory symptoms and diagnoses were obtained at ages 2, 3, 6, 8, 11, 13, 16, and 18 years. Boys were significantly more likely than girls to experience both wheeze and frequent wheeze most years in the first decade of life. However, girls with symptoms were less likely than boys to see a physician (74.1% vs. 83.4%, P < 0.001) and to be labeled as having asthma (43.3% vs. 53.8%, P < 0.009), even after adjusting for symptom frequency. A difference in symptom presentation also appeared to influence diagnosis: nocturnal cough without frequent wheeze was more prevalent among girls, and was associated with reduced diagnosis of asthma. Among subjects who consulted a physician for wheeze, boys were significantly more likely than girls to have taken medication (81.5% vs. 73.5%, P < 0.01). The lag time between age at first wheeze and first use of medication among those consulting a physician for wheeze or asthma was greater for girls, especially among subjects with frequent wheeze (2.8 vs. 1.6 years, P < 0.005). These findings indicate that gender differences in the diagnosis and treatment of asthma cannot be explained completely by differences in symptom prevalence and frequency.