Seasonal risk factors for asthma exacerbations among inner-city children

BACKGROUND

Asthma exacerbations remain common, even in children and adolescents, despite optimal medical management. Identification of host risk factors for exacerbations is incomplete, particularly for seasonal episodes.

OBJECTIVE

We sought to define host risk factors for asthma exacerbations unique to their season of occurrence.

METHODS

This is a retrospective analysis of patients aged 6 to 20 years who comprised the control groups of the Asthma Control Evaluation study and the Inner City Anti-IgE Therapy for Asthma study. Univariate and multivariate models were constructed to determine whether patients' demographic and historical factors, allergic sensitization, fraction of exhaled nitric oxide values, spirometric measurements, asthma control, and treatment requirements were associated with seasonal exacerbations.

RESULTS

The analysis included 400 patients (54.5% male; 59.0% African American; median age, 13 years). Exacerbations occurred in 37.5% of participants over the periods of observation and were most common in the fall (28.8% of participants). In univariate analysis impaired pulmonary function was significantly associated with greater odds of exacerbations for all seasons, as was an exacerbation in the previous season for all seasons except spring. In multivariate analysis exacerbation in the previous season was the strongest predictor in fall and winter, whereas a higher requirement for inhaled corticosteroids was the strongest predictor in spring and summer. The multivariate models had the best predictive power for fall exacerbations (30.5% variance attributed).

CONCLUSIONS

Among a large cohort of inner-city children with asthma, patients' risk factors for exacerbation vary by season. Thus information on individual patients might be beneficial in strategies to prevent these seasonal events.

Inner city asthma

The inner city has long been recognized as an area of high asthma morbidity and mortality. A wide range of factors interact to create this environment. These factors include well-recognized asthma risk factors that are not specific to the inner city, the structure and delivery of health care, the location and function of the urban environment, and social inequities. In this article, these facets are reviewed, and successful and unsuccessful interventions are discussed, to understand what is needed to solve this problem.

Circulating TSLP associates with decreased wheezing in non-atopic preschool children: data from the URECA birth cohort

BACKGROUND

Mouse models of atopic march suggest that systemic, skin-derived thymic stromal lymphopoietin (TSLP) mediates progression from eczema to asthma.

OBJECTIVE

We investigated whether circulating TSLP is associated with eczema, allergic sensitization, or recurrent wheezing in young children.

METHODS

A prospective analysis of the relationship between plasma levels of TSLP to allergic sensitization and recurrent wheezing was conducted in the birth cohort from the Urban Environment and Childhood Asthma (URECA) study. Plasma TSLP levels were measured at 1, 2, and 3 years of age and analysed for correlation with clinical parameters in each of the three years. Only those children with consecutive samples for all three years were included in this analysis.

RESULTS

We detected TSLP in 33% of 236 children for whom plasma samples were available for all three years. Overall, a consistently significant association was not found between TSLP and eczema or allergic sensitization. With regard to recurrent wheezing, children with detectable TSLP at one year of age were significantly less likely to experience recurrent wheezing by 3 years compared with those children without detectable TSLP, but this was only seen in children without aeroallergen sensitization at 3 years (P < 0.01).

CONCLUSIONS AND CLINICAL RELEVANCE

Contrary to our expectations, circulating TSLP was not significantly associated with eczema, allergen sensitization, or recurrent wheezing during the first three years of life. Early presence of circulating TSLP was significantly associated with reduced incidence of recurrent wheeze in those children not sensitized to aeroallergen. These findings suggest a possible underlying distinction between pathogenesis of developing atopic vs. non-atopic recurrent wheeze.

Influence of early-life exposures on food sensitization and food allergy in an inner-city birth cohort

OBJECTIVE

Previous data suggest that food allergy (FA) might be more common in inner-city children; however, these studies have not collected data on both sensitization and clinical reactivity or early-life exposures.

METHODS

Children in the Urban Environment and Childhood Asthma birth cohort were followed through age 5 years. Household exposures, diet, clinical history, and physical examinations were assessed yearly; levels of specific IgE to milk, egg, and peanut were measured at 1, 2, 3, and 5 years of age. On the basis of sensitization (IgE ≥0.35 kU/L) and clinical history over the 5-year period, children were classified as having FA or being possibly allergic, sensitized but tolerant, or not allergic/not sensitized.

RESULTS

Five hundred sixteen children were included. Overall, 55.4% were sensitized (milk, 46.7%; egg, 31.0%; and peanut, 20.9%), whereas 9.9% were categorized as having FA (peanut, 6.0%; egg, 4.3%; and milk, 2.7%; 2.5% to >1 food). The remaining children were categorized as possibly allergic (17.0%), sensitized but tolerant (28.5%), and not sensitized (44.6%). Eighteen (3.5%) reported reactions to foods for which IgE levels were not measured. Food-specific IgE levels were similar in children with FA versus sensitized but tolerant children, except for egg, levels of which were higher in patients with FA at ages 1 and 2 years. FA was associated with recurrent wheeze, eczema, aeroallergen sensitization, male sex, breast-feeding, and lower endotoxin exposure in year 1 but not with race/ethnicity, income, tobacco exposure, maternal stress, or early introduction of solid foods.

CONCLUSIONS

Even given that this was designed to be a high-risk cohort, the cumulative incidence of FA is extremely high, especially considering the strict definition of FA that was applied and that only 3 common allergens were included.

Birth cohorts in asthma and allergic diseases: report of a NIAID/NHLBI/MeDALL joint workshop

Population-based birth cohorts on asthma and allergies increasingly provide new insights into the development and natural history of the diseases. More than 130 birth cohorts focusing on asthma and allergy have been initiated in the last 30 years. A National Institute of Allergy and Infectious Diseases; National Heart, Lung, and Blood Institute; Mechanisms of the Development of Allergy (MeDALL; Framework Programme 7 of the European Commission) joint workshop was held in Bethesda, Maryland, on September 11-12, 2012, with 3 objectives: (1) documenting the knowledge that asthma/allergy birth cohorts have provided, (2) identifying the knowledge gaps and inconsistencies, and (3) developing strategies for moving forward, including potential new study designs and the harmonization of existing asthma birth cohort data. The meeting was organized around the presentations of 5 distinct workgroups: (1) clinical phenotypes, (2) risk factors, (3) immune development of asthma and allergy, (4) pulmonary development, and (5) harmonization of existing birth cohorts. This article presents the workgroup reports and provides Web links (AsthmaBirthCohorts.niaid.nih.gov or www.medall-fp7.eu), where the reader will find tables describing the characteristics of the birth cohorts included in this report, the type of data collected at differing ages, and a selected bibliography provided by the participating birth cohorts.

Age-dependent interaction between atopy and eosinophils in asthma cases: results from NHANES 2005-2006

BACKGROUND

Atopy is an established risk factor for asthma, and an elevated eosinophil level is a hallmark of atopic and non-atopic asthma. Whether atopy and eosinophils act independently or interact to influence asthma has clinical and public health implications.

OBJECTIVE

To investigate the relationship between atopy and eosinophils in asthma.

METHODS

Data on current asthma, atopy (IgE positive to ≥ 1 allergen), and blood eosinophil percent (dichotomized at the median) were obtained for persons aged ≥ 6 years from the National Health and Nutrition Examination Survey 2005-2006. Interaction on an additive scale was evaluated by estimating the prevalences of asthma for combinations of atopy (yes or no) and eosinophil percent (high or low) and calculating the excess prevalence due to interaction.

RESULTS

For all ages combined, the adjusted prevalences of asthma were 4.6%, 7.6%, 6.9% and 17.2% for persons with neither factor, atopy alone, a high eosinophil percent alone and both factors respectively. The excess prevalence of asthma due to interaction was 7.2%, indicating synergism. The excess prevalence was greatest in children aged 6-17 years (15.3%), and it decreased with each older age category until it was absent in adults aged ≥ 55 years (-0.2%). In children, 94% of asthma cases attributable to the 2 factors were attributable to the interaction, whereas in the oldest adults, no cases were attributable to the interaction.

CONCLUSIONS AND CLINICAL RELEVANCE

Interaction between atopy and an elevated eosinophil level in asthma cases was very strong in children but absent in the oldest adults, which suggests different mechanistic pathways for these factors by age and supports the notion that asthma is a heterogeneous disease. In addition, the age-dependent interaction between the factors has potential implications for the selection of asthma patients for treatments that would target either IgE or a high eosinophil level.

Lack of a relation between serum 25-hydroxyvitamin D concentrations and asthma in adolescents

BACKGROUND

Decreased 25-hydroxyvitamin D [25(OH)D] concentrations have been associated with an increased prevalence and severity of asthma and a lower response to inhaled corticosteroids.

OBJECTIVE

The objective was to determine the association between serum 25(OH)D concentrations and asthma prevalence, severity, and response to asthma treatment.

DESIGN

Secondary analyses were conducted in 2 samples of adolescents 12-20 y of age: 1) NHANES 2001-2006 (n = 6487), a cross-sectional nationally representative sample of the US population, and 2) a cohort of inner-city adolescents with asthma managed prospectively for 46 wk with guidelines-based therapy in the Asthma Control Evaluation (ACE; n = 226) trial.

RESULTS

Mean (±SD) serum 25(OH)D concentrations in the NHANES and ACE samples were lower in African Americans than in non-African Americans (NHANES: 14.9 ± 6.5 compared with 23.0 ± 8.4 ng/mL, P < 0.0001; ACE: 11.2 ± 6.9 compared with 15.8 ± 7.1 ng/mL, P < 0.0001). In the NHANES sample, mean concentrations did not differ between participants without and with asthma (African Americans: 14.9 ± 6.4 compared with 15.0 ± 6.6 ng/mL, respectively, P = 0.87; non-African Americans: 23.0 ± 8.5 compared with 23.6 ± 8.2 ng/mL, respectively, P = 0.16). In the ACE models that used either a predefined cutoff (<20 ng/mL) or linear regression, 25(OH)D concentrations showed either no relation or minor contradictory correlations with indicators of asthma severity, treatment requirements, spirometry, or atopy/inflammation.

CONCLUSION

In 2 samples of adolescents, overall serum 25(OH)D concentrations were low and were not consistently associated with the presence of asthma, multiple asthma characteristics, asthma morbidity, or response to treatment. The ACE trial was registered at clinicaltrials.gov as NCT0011441.

Reassessment of omalizumab-dosing strategies and pharmacodynamics in inner-city children and adolescents

BACKGROUND

Treatment regimens for omalizumab are guided by a dosing table that is based on total serum IgE and body weight. Limited data exist about onset and offset of omalizumab efficacy in children and adolescents or subgroups that most benefit from treatment.

OBJECTIVES

Post hoc analyses were conducted to (1) examine patient characteristics of those eligible and ineligible for omalizumab, (2) describe onset of effect after initiation of omalizumab and offset of treatment effect after stopping therapy, and (3) determine whether the efficacy differs by age, asthma severity, dosing regimen, and prespecified biomarkers.

METHODS

Inner-city children and adolescents with persistent allergic asthma were enrolled in the Inner-City Anti-IgE Therapy for Asthma trial that compared omalizumab with placebo added to guidelines-based therapy for 60 weeks.

RESULTS

Two hundred ninety-three of 889 participants (33%) clinically suitable for omalizumab were ineligible for dosing according to a modified dosing table specifying IgE level and body weight criteria. Baseline symptoms were comparable among those eligible and ineligible to receive omalizumab, but other characteristics (rate of health care utilization and skin test results) differed. The time of onset of omalizumab effect was <30 days and time of offset was between 30 and 120 days. No difference in efficacy was noted by age or asthma severity, but high exhaled nitric oxide, blood eosinophils, and body mass index predicted efficacy.

CONCLUSIONS

A significant portion of children and adolescents particularly suited for omalizumab because of asthma severity status may be ineligible due to IgE >1300 IU/mL. Omalizumab reduced asthma symptoms and exacerbations rapidly; features associated with efficacy can be identified to guide patient selection.

A study of the use of impulse oscillometry in the evaluation of children with asthma: analysis of lung parameters, order effect, and utility compared with spirometry

BACKGROUND

The ability to objectively measure lung function in children is critical in the assessment and treatment of asthma in this age group. We thus determined the effectiveness of impulse oscillometry (IOS) as a non-invasive technique to assess lung function in children and in comparison to spirometry for sensitivity and specificity, testing variability, and the order effect of sequential testing of IOS and spirometry.

METHODS

One hundred seventeen children sequentially evaluated in a pediatric clinic and under medical care for disease, were asked to perform IOS and spirometry. The utility of IOS and spirometry in differentiating children that had asthma versus those children who did not was then analyzed.

RESULTS

In the primary analysis (n = 117), bronchodilator response using IOS distinguished asthmatics from non-asthmatics, P = 0.0008 for R10. Receiver-operator characteristic curve (ROC) analysis of R10 bronchodilator response at the best cut-off (-8.6% change) correctly identified 77% of patients with asthma and excluded 76% of non-asthmatics. Amongst those children able to perform spirometry (asthmatics, n = 66; non-asthmatics, n = 16), FEV(1) did not reveal a difference between these two groups, while area of reactance (AX) did distinguish these groups (P = 0.0092). Sequential testing of IOS and then spirometry (n = 47) showed a significant decrement in lung function as determined by IOS following performance of spirometry (P = 0.0309).

CONCLUSION

In the diagnosis and management of children with lung disease, IOS is a non-invasive approach that easily and objectively measures lung impedance and should be considered as both an adjunct, and in some situations, an alternative to standard spirometry.

Allergy-related outcomes in relation to serum IgE: results from the National Health and Nutrition Examination Survey 2005-2006

BACKGROUND

The National Health and Nutrition Examination Survey (NHANES) 2005-2006 was the first population-based study to investigate levels of serum total and allergen-specific IgE in the general US population.

OBJECTIVE

We estimated the prevalence of allergy-related outcomes and examined relationships between serum IgE levels and these outcomes in a representative sample of the US population.

METHODS

Data for this cross-sectional analysis were obtained from NHANES 2005-2006. Study subjects aged 6 years and older (n = 8086) had blood taken for measurement of total IgE and 19 specific IgE levels against common aeroallergens, including Alternaria alternata, Aspergillus fumigatus, Bermuda grass, birch, oak, ragweed, Russian thistle, rye grass, cat dander, cockroach, dog dander, dust mite (Dermatophagoides farinae and Dermatophagoides pteronyssinus), mouse and rat urine proteins, and selected foods (egg white, cow's milk, peanut, and shrimp). Serum samples were analyzed for total and allergen-specific IgE by using the Pharmacia CAP System. Information on allergy-related outcomes and demographics was collected by questionnaire.

RESULTS

In NHANES 2005-2006, 6.6% reported current hay fever, and 23.5% had current allergies. Allergy-related outcomes increased with increasing total IgE levels (adjusted odds ratios for a 10-fold increase in total IgE level of 1.86 [95% CI, 1.44-2.41] for hay fever and 1.64 [95% CI, 1.41-1.91] for allergies). Increased levels of plant-, pet-, and mold-specific IgE contributed independently to allergy-related symptoms. The greatest increase in odds was observed for hay fever and plant-specific IgE (adjusted odds ratio, 4.75; 95% CI, 3.83-5.88).

CONCLUSION

In the US population self-reported allergy symptoms are most consistently associated with increased levels of plant-, pet-, and mold-specific IgE.

Allergy-related outcomes in relation to serum IgE: results from the National Health and Nutrition Examination Survey 2005-2006

BACKGROUND

The National Health and Nutrition Examination Survey (NHANES) 2005-2006 was the first population-based study to investigate levels of serum total and allergen-specific IgE in the general US population.

OBJECTIVE

We estimated the prevalence of allergy-related outcomes and examined relationships between serum IgE levels and these outcomes in a representative sample of the US population.

METHODS

Data for this cross-sectional analysis were obtained from NHANES 2005-2006. Study subjects aged 6 years and older (n = 8086) had blood taken for measurement of total IgE and 19 specific IgE levels against common aeroallergens, including Alternaria alternata, Aspergillus fumigatus, Bermuda grass, birch, oak, ragweed, Russian thistle, rye grass, cat dander, cockroach, dog dander, dust mite (Dermatophagoides farinae and Dermatophagoides pteronyssinus), mouse and rat urine proteins, and selected foods (egg white, cow's milk, peanut, and shrimp). Serum samples were analyzed for total and allergen-specific IgE by using the Pharmacia CAP System. Information on allergy-related outcomes and demographics was collected by questionnaire.

RESULTS

In NHANES 2005-2006, 6.6% reported current hay fever, and 23.5% had current allergies. Allergy-related outcomes increased with increasing total IgE levels (adjusted odds ratios for a 10-fold increase in total IgE level of 1.86 [95% CI, 1.44-2.41] for hay fever and 1.64 [95% CI, 1.41-1.91] for allergies). Increased levels of plant-, pet-, and mold-specific IgE contributed independently to allergy-related symptoms. The greatest increase in odds was observed for hay fever and plant-specific IgE (adjusted odds ratio, 4.75; 95% CI, 3.83-5.88).

CONCLUSION

In the US population self-reported allergy symptoms are most consistently associated with increased levels of plant-, pet-, and mold-specific IgE.

Relationships among environmental exposures, cord blood cytokine responses, allergy, and wheeze at 1 year of age in an inner-city birth cohort (Urban Environment and Childhood Asthma study)

BACKGROUND

The Urban Environment and Childhood Asthma study was established to investigate the immunologic and environmental causes of asthma in inner-city children.

OBJECTIVE

We sought to evaluate potential atopic outcomes in the first 12 months and their relationships to environmental exposures and immune development.

METHODS

A birth cohort of 560 children with at least 1 parent with allergy or asthma was established in Baltimore, Boston, New York, and St Louis. Wheezing is assessed every 3 months, allergen-specific IgE yearly, and mononuclear cell cytokine responses at birth and yearly; environmental assessments include dust allergen and endotoxin, maternal stress, and indoor nicotine and nitrogen dioxide levels.

RESULTS

Key outcomes in the first year include wheeze in 49%, 2 or more episodes of wheeze in 23%, eczema in 30%, and detectable IgE to milk, egg, and/or peanut in 32% and to cockroach in 4%. Household dust revealed levels of greater than 2 μg/g to cockroach in 40%, mite in 19%, cat in 25%, and mouse in 29%, and 66% of homes housed at least 1 smoker. Positive associations were detected between multiple wheeze and cotinine levels, maternal stress, and maternal depression, whereas cytokine responses to a variety of innate, adaptive, and mitogenic stimuli were inversely related to eczema.

CONCLUSIONS

This high-risk cohort of inner-city infants is exhibiting high rates of wheeze, eczema, and allergic sensitization. Low cytokine responses at birth might be a risk factor for eczema, whereas a variety of adverse environmental exposures contribute to the risk of wheezing in infancy. These findings provide evidence of specificity in the interactions between immune development, environmental exposures, and the development of early features that might predict future asthma.

Randomized trial of omalizumab (anti-IgE) for asthma in inner-city children

BACKGROUND

Research has underscored the effects of exposure and sensitization to allergens on the severity of asthma in inner-city children. It has also revealed the limitations of environmental remediation and guidelines-based therapy in achieving greater disease control.

METHODS

We enrolled inner-city children, adolescents, and young adults with persistent asthma in a randomized, double-blind, placebo-controlled, parallel-group trial at multiple centers to assess the effectiveness of omalizumab, as compared with placebo, when added to guidelines-based therapy. The trial was conducted for 60 weeks, and the primary outcome was symptoms of asthma.

RESULTS

Among 419 participants who underwent randomization (at which point 73% had moderate or severe disease), omalizumab as compared with placebo significantly reduced the number of days with asthma symptoms, from 1.96 to 1.48 days per 2-week interval, a 24.5% decrease (P<0.001). Similarly, omalizumab significantly reduced the proportion of participants who had one or more exacerbations from 48.8 to 30.3% (P<0.001). Improvements occurred with omalizumab despite reductions in the use of inhaled glucocorticoids and long-acting beta-agonists.

CONCLUSIONS

When added to a regimen of guidelines-based therapy for inner-city children, adolescents, and young adults, omalizumab further improved asthma control, nearly eliminated seasonal peaks in exacerbations, and reduced the need for other medications to control asthma. (Funded by the National Institute of Allergy and Infectious Diseases and Novartis; ClinicalTrials.gov number, NCT00377572.).

Allergen-specific IgE as a biomarker of exposure plus sensitization in inner-city adolescents with asthma

BACKGROUND

Relationships among allergen-specific IgE levels, allergen exposure and asthma severity are poorly understood since sensitization has previously been evaluated as a dichotomous, rather than continuous characteristic.

METHODS

Five hundred and forty-six inner-city adolescents enrolled in the Asthma Control Evaluation study underwent exhaled nitric oxide (FE(NO)) measurement, lung function testing, and completion of a questionnaire. Allergen-specific IgE levels and blood eosinophils were quantified. Dust samples were collected from the participants' bedrooms for quantification of allergen concentrations. Participants were followed for 12 months and clinical outcomes were tracked.

RESULTS

Among sensitized participants, allergen-specific IgE levels were correlated with the corresponding settled dust allergen levels for cockroach, dust mite, and mouse (r = 0.38, 0.34, 0.19, respectively; P < 0.0001 for cockroach and dust mite and P = 0.03 for mouse), but not cat (r = -0.02, P = 0.71). Higher cockroach-, mite-, mouse-, and cat-specific IgE levels were associated with higher FE(NO) concentrations, poorer lung function, and higher blood eosinophils. Higher cat, dust mite, and mouse allergen-specific IgE levels were also associated with an increasing risk of exacerbations or hospitalization.

CONCLUSIONS

Allergen-specific IgE levels were correlated with allergen exposure among sensitized participants, except for cat. Allergen-specific IgE levels were also associated with more severe asthma across a range of clinical and biologic markers. Adjusting for exposure did not provide additional predictive value, suggesting that higher allergen-specific IgE levels may be indicative of both higher exposure and a greater degree of sensitization, which in turn may result in greater asthma severity.

Asthma in the inner city: the perspective of the National Institute of Allergy and Infectious Diseases

Since 1991, the National Institute of Allergy and Infectious Diseases (NIAID) has funded four consecutive research initiatives to investigate the problem of high asthma prevalence, morbidity and mortality in poor urban communities. The multi-site studies conducted under these initiatives have identified key risk factors for asthma morbidity and novel interventions to improve asthma control. NIAID focuses its asthma and allergy programs on understanding the interaction of the immune system with allergens and infectious agents and identifying genetic and epigenetic elements that influence the immune system. A key goal in this field is to define mechanisms of immune system deviation and immune tolerance and apply this knowledge to generate improvements in asthma care and allergen immunotherapy. A related goal is to further understand the environmental, social, and immunological elements that impact on the development of inner-city asthma through in-depth characterization and longitudinal follow-up of inner-city children from the time of birth. In the past 5 years, NIH budgetary constraints have imposed many challenges for the academic research community. Despite these constraints, NIAID has maintained its support of a highly productive asthma and allergy research program.

Achieving asthma control in the inner city: do the National Institutes of Health Asthma Guidelines really work?

For children living in inner cities, asthma tends to be more frequent and severe. To characterize, understand, and treat children with asthma living in the inner city more effectively, the National Institute of Allergy and Infectious Diseases established an Inner-City Asthma Program in 1991. In addition, the revised National Asthma Education and Prevention Program Expert Panel 3 report was introduced with new concepts for asthma management that are now centered on asthma control. The purpose of this review is to highlight features of the National Institute of Allergy and Infectious Diseases Inner-City Asthma Consortium Asthma Control Evaluation study that enhance our knowledge regarding the application of the asthma guidelines and to provide a summary of lessons learned from that important study. We recognized that asthma symptoms and exacerbations are theoretically linked to underlying inflammation of airways but are not direct indicators of inflammation. Based on the observations from the Asthma Control Evaluation study, we were impressed that a systematic guidelines-based approach improved asthma control significantly over the course of the 1-year treatment period.

Asthma control, adiposity, and adipokines among inner-city adolescents

BACKGROUND

There is an association between adiposity and asthma prevalence, but the relationship to asthma control is unclear.

OBJECTIVES

We sought to understand the relationships among adiposity, sex, and asthma control in inner-city adolescents with asthma.

METHODS

We prospectively followed 368 adolescents with moderate-to-severe asthma (ages 12-20 years) living in 10 urban areas for 1 year. Asthma symptoms and exacerbations were recorded, and pulmonary function and exhaled nitric oxide levels were measured every 6 weeks. Adiposity measures (body mass index [BMI] and dual-energy X-ray absorptiometric scans) were made, and blood was collected for measurement of allergy markers, adiponectin, leptin, TNF-alpha, IL-6, and C-reactive protein levels.

RESULTS

More than 60% of female subjects and 50% of male subjects were above the 85th percentile of BMI for age. Higher BMI was associated with more symptom days (R = 0.18, P = .02) and exacerbations (R = 0.18, P = .06) among female subjects only. Adiponectin was inversely related to asthma symptoms (R = -0.18, P < .05) and exacerbations (R = -0.20, P < .05) and positively with FEV(1)/forced vital capacity ratio (R = 0.15, P < .05) in male subjects only independent of body size. There was no relationship between adiposity or adipokines and total IgE levels, blood eosinophil counts, and exhaled nitric oxide levels. Dual-energy X-ray absorptiometry provided little additional value in relating adiposity to asthma outcome in this population of adolescents.

CONCLUSION

Adiposity is associated with poorer asthma control in female subjects. Adiponectin is associated with improved asthma control in male subjects.

Total IgE levels and asthma prevalence in the US population: results from the National Health and Nutrition Examination Survey 2005-2006

BACKGROUND

The inability to measure IgE-based sensitivity to all allergens has limited our understanding of what portion of asthma is related to IgE. Total IgE measurement can potentially overcome this limitation.

OBJECTIVE

We sought to determine the association between total IgE levels and asthma.

METHODS

The National Health and Nutrition Examination Survey 2005-2006 examined a representative sample of the US population 6 years of age and older.

RESULTS

The median total IgE level was 40.8 kU/L (interquartile range, 15.5-114 kU/L). Total IgE levels varied with age, sex, race/ethnicity, serum cotinine level, body size, and socioeconomic status. The prevalence of current asthma was 8.8%. The prevalence of atopy was 42.5%, as defined by 15 specific IgEs. The adjusted odds ratio (OR) for asthma with a 10-fold increase in total IgE level was 2.18 (95% CI, 1.66-2.87). Total IgE level predicted asthma only among atopic subjects (OR, 2.41; 95% CI, 1.62-3.60) and not among nonatopic subjects (OR, 1.11; 95% CI, 0.72-1.71; interaction P = .005). Among atopic subjects, the association between total IgE level and asthma became stronger as the number of positive specific IgE test results increased. Asthma was present at even the lowest levels of total IgE, regardless of atopic status. Approximately 92% of atopic subjects were identified by 6 specific IgEs, but to increase the identification to more than 99% required 11 specific IgEs.

CONCLUSION

Total IgE levels are associated with asthma only among persons who have positive results for at least 1 allergen-specific IgE. Asthma independent of IgE is not uncommon in the US population. The complete identification of atopic subjects in a population requires a large panel of allergen-specific IgEs.

Asthma morbidity among inner-city adolescents receiving guidelines-based therapy: role of predictors in the setting of high adherence

BACKGROUND

With the expanding effort to provide guidelines-based therapy to adolescents with asthma, attention must be directed to evaluating which factors predict future asthma control when guidelines-based management is applied.

OBJECTIVE

We evaluated the role of fraction of exhaled nitric oxide in parts per billion, markers of allergic sensitization, airway inflammation, and measures of asthma severity in determining future risk of asthma symptoms and exacerbations in adolescents and young adults participating in the Asthma Control Evaluation study.

METHODS

Five hundred forty-six inner-city residents, ages 12 through 20 years, with persistent asthma were extensively evaluated at study entry for predictors of future symptoms and exacerbations over the subsequent 46 weeks, during which guidelines-based, optimal asthma management was offered. Baseline measurements included fraction of exhaled nitric oxide in parts per billion, total IgE, allergen-specific IgE, allergen skin test reactivity, asthma symptoms, lung function, peripheral blood eosinophils, and, for a subset, airway hyperresponsiveness and sputum eosinophils.

RESULTS

The baseline characteristics we examined accounted for only a small portion of the variance for future maximum symptom days and exacerbations--11.4% and 12.6%, respectively. Future exacerbations were somewhat predicted by asthma symptoms, albuterol use, previous exacerbations, and lung function, whereas maximum symptom days were predicted, also to a modest extent, by symptoms, albuterol use, and previous exacerbations, but not lung function.

CONCLUSION

Our findings demonstrate that the usual predictors of future disease activity have little predictive power when applied to a highly adherent population with persistent asthma that is receiving guidelines-based care. Thus, new predictors need to be identified that will be able to measure the continued fluctuation of disease that persists in highly adherent, well-treated populations such as the one studied.

The Urban Environment and Childhood Asthma (URECA) birth cohort study: design, methods, and study population

BACKGROUND

The incidence and morbidity of wheezing illnesses and childhood asthma is especially high in poor urban areas. This paper describes the study design, methods, and population of the Urban Environment and Childhood Asthma (URECA) study, which was established to investigate the immunologic causes of asthma among inner-city children.

METHODS AND RESULTS

URECA is an observational prospective study that enrolled pregnant women in central urban areas of Baltimore, Boston, New York City, and St. Louis and is following their offspring from birth through age 7 years. The birth cohort consists of 560 inner-city children who have at least one parent with an allergic disease or asthma, and all families live in areas in which at least 20% of the population has incomes below the poverty line. In addition, 49 inner-city children with no parental history of allergies or asthma were enrolled. The primary hypothesis is that specific urban exposures in early life promote a unique pattern of immune development (impaired antiviral and increased Th2 responses) that increases the risk of recurrent wheezing and allergic sensitization in early childhood, and of asthma by age 7 years. To track immune development, cytokine responses of blood mononuclear cells stimulated ex vivo are measured at birth and then annually. Environmental assessments include allergen and endotoxin levels in house dust, pre- and postnatal maternal stress, and indoor air nicotine and nitrogen dioxide. Nasal mucous samples are collected from the children during respiratory illnesses and analyzed for respiratory viruses. The complex interactions between environmental exposures and immune development will be assessed with respect to recurrent wheeze at age 3 years and asthma at age 7 years.

CONCLUSION

The overall goal of the URECA study is to develop a better understanding of how specific urban exposures affect immune development to promote wheezing illnesses and asthma.

Mediator release assay for assessment of biological potency of German cockroach allergen extracts

BACKGROUND

Cockroach is an important allergen in inner-city asthma. The diagnosis and treatment of cockroach allergy has been impeded by the lack of standardized cockroach extracts.

OBJECTIVE

We investigated the utility of a mediator release assay based on rat basophil leukemia (RBL) cells for comparing the potency of German cockroach extracts.

METHODS

RBL cells (line 2H3) transfected with human FcepsilonRI were passively sensitized with sera from subjects with cockroach allergy and stimulated with serial dilutions of 3 commercial cockroach extracts (1:10 weight/volume). In addition, the in-house prepared extract was tested in separate experiments with pooled sera that produced optimal performance in the RBL assay. N-hexosaminidase release (NHR) was used as a marker of RBL cell degranulation and was examined in relation to the intradermal skin test (ID(50)EAL) and serum cockroach-specific and total IgE levels.

RESULTS

The median cockroach-specific IgE concentration in 60 subjects was 0.72 kU(A)/L (interquartile range, 0.35-2.97 kU(A)/L); 19 sera (responders) produced a minimum 10% NHR to more than 1 extract. Responders had higher median cockroach-specific IgE (7.4 vs 1.0 kU(A)/L) and total IgE (429 vs 300 kU/L) levels than nonresponders. Ranking of extract potency was consistent between the mediator release assay and the ID(50)EAL. For the in-house prepared cockroach extract, the dose-response curves were shifted according to the concentration of the extract. NHR was reproducible between different experiments by using pooled sera.

CONCLUSION

The mediator release assay measures biologic potency and correlates with the ID(50)EAL. It should be further evaluated to determine whether it could be used to replace intradermal skin test titration for assessing the potency of cockroach extract.

Effect of environmental allergen sensitization on asthma morbidity in inner-city asthmatic children

BACKGROUND

Asthma causes significant morbidity in children, and studies have demonstrated that environmental allergies contribute to increased asthma morbidity.

OBJECTIVE

We investigated the differences between allergen skin tests and specific IgE (SIgE) and the role of IgG in regards to allergen exposure levels, and asthma morbidity in inner-city children.

METHODS

Five hundred and six serum samples from the National Cooperative Inner City Asthma Study (NCICAS) were evaluated for SIgE to cockroach (Blattella germanica), dust mite (Dermatophagoides farinae), and Alternaria as well as specific IgG (SIgG) and IgG(4) to cockroach (B. germanica) and total IgE levels. Associations between sensitization to these allergens, exposures, and asthma morbidity were determined.

RESULTS

Sensitization to environmental allergens and total IgE correlated with increased health care and medication use, but not with symptoms of wheeze. Sensitization with exposure to cockroach was associated with increased asthma morbidity, whereas dust mite sensitization was correlated with asthma morbidity independent of exposure. There was also a strong correlation between SIgE levels and skin test results, but the tests did not always agree. The relationship between SIgE and asthma morbidity is linear with no obvious cutoff value. Increased Bla g 1 in the home was a good predictor for sensitization; however, this relationship was not demonstrated for Der f 1. Cockroach SIgG correlated with increased health care use, however, there was no modifying effect of SIgG or SIgG(4) on the association between cockroach SIgE and asthma morbidity.

CONCLUSIONS

SIgE levels and skin prick test results to environmental allergens can serve as markers of severe asthma for inner-city children. Asthma morbidity increased in a linear manner with SIgE levels. IgG was not an important predictor or modifier of asthma morbidity.

Management of asthma based on exhaled nitric oxide in addition to guideline-based treatment for inner-city adolescents and young adults: a randomised controlled trial

BACKGROUND

Preliminary evidence is equivocal about the role of exhaled nitric oxide (NO) in clinical asthma management. We aimed to assess whether measurement of exhaled NO, as a biomarker of airway inflammation, could increase the effectiveness of asthma treatment, when used as an adjunct to clinical care based on asthma guidelines for inner-city adolescents and young adults.

METHODS

We did a randomised, double-blind, parallel-group trial at ten centres in the USA. We screened 780 inner-city patients, aged 12-20 years, who had persistent asthma. All patients completed a run-in period of 3 weeks on a regimen based on standard treatment. 546 eligible participants who adhered to treatment during this run-in period were then randomly assigned to 46 weeks of either standard treatment, based on the guidelines of the National Asthma Education and Prevention Program (NAEPP), or standard treatment modified on the basis of measurements of fraction of exhaled NO. The primary outcome was the number of days with asthma symptoms. We analysed patients on an intention-to-treat basis. This trial is registered with clinicaltrials.gov, number NCT00114413.

FINDINGS

During the 46-week treatment period, the mean number of days with asthma symptoms did not differ between the treatment groups (1.93 [95% CI 1.74 to 2.11] in the NO monitoring group vs 1.89 [1.71 to 2.07] in the control group; difference 0.04 [-0.22 to 0.29], p=0.780). Other symptoms, pulmonary function, and asthma exacerbations did not differ between groups. Patients in the NO monitoring group received higher doses of inhaled corticosteroids (difference 119 mug per day, 95% CI 49 to 189, p=0.001) than controls. Adverse events did not differ between treatment groups (p>0.1 for all adverse events).

INTERPRETATION

Conventional asthma management resulted in good control of symptoms in most participants. The addition of fraction of exhaled NO as an indicator of control of asthma resulted in higher doses of inhaled corticosteroids, without clinically important improvements in symptomatic asthma control.

Biological potency of German cockroach allergen extracts determined in an inner city population

BACKGROUND

Cockroach allergy is an important cause of inner city asthma. To perform valid studies on the diagnosis and treatment of cockroach allergy, biological potencies of test extracts need to be established, and a surrogate in vitro test for biological potency should be chosen.

METHODS

Sixty-two cockroach-allergic adult subjects were recruited for quantitative skin testing with three commercial German cockroach extracts. The intradermal D50 values were determined using linear interpolation, and the biologic potencies were determined from D50 data. The extracts were also analysed for relative potency, using a competition ELISA, and for specific allergen content, using a two-site ELISA.

RESULTS

Estimates of each extract's D50 were analysable in 48-55 subjects, with D50s between 10.3 and 11.8. All three extracts were bioequivalent using pre-set criteria. The biological potencies of the extracts were 1738-8570 bioequivalent allergy units (BAU)/mL (geometric mean=3300), and these relative potencies were similar to those estimated by competition ELISA and specific allergen content. IgE against cockroach allergens were detected in sera from 34 subjects with analysable D50s, and 17 subjects had IgE directed against specific cockroach allergens. Although the presence of anti-Bla g 5 correlated with the subjects' skin test responses for 2/3 extracts, no single allergen was immunodominant. Antibody responses among the subjects were heterogeneous.

CONCLUSIONS

Although commercial cockroach extracts are relatively low in potency, immunotherapeutic doses should be achievable. Biological potency may be estimated using D50 testing, a combination of specific allergen determinations, or by an overall potency assay such as the competition ELISA.

CAPSULE SUMMARY

The biological potency of three German cockroach allergen extracts, determined in an inner city population, was 1738-8570 BAU/mL. No one allergen was immunodominant, and surrogate in vitro testing methods were examined.

Asthma cases attributable to atopy: results from the Third National Health and Nutrition Examination Survey

BACKGROUND

The percentage of asthma cases attributable to atopy is the subject of debate.

OBJECTIVES

The objectives were to estimate the percentage of asthma cases in the US population attributable to atopy and to examine associations between allergen-specific skin tests and asthma.

METHODS

Data were obtained from the Third National Health and Nutrition Examination Survey, in which subjects age 6 to 59 years were skin tested with 10 allergens. Atopy was defined as at least 1 positive allergen-specific test. Doctor-diagnosed current asthma was assessed by questionnaire.

RESULTS

In the United States, 56.3% of the asthma cases were attributable to atopy, and that percentage was greater among males than females, among persons in the highest education category than in lower education categories, and among persons living in highly populated metropolitan areas than in all other areas. Each allergen-specific test was strongly associated with asthma before adjustment (odds ratios varied from 2.1 to 4.5); however, after adjustment by all the allergens, only tests to cat, Alternaria, white oak, and perennial rye were independently associated with asthma. Perennial rye was inversely associated with asthma. Of the 10 allergens, a positive response to cat accounted for the highest percentage of asthma cases (29.3%).

CONCLUSION

About half of the current asthma cases in the US population represented by the Third National Health and Nutrition Examination Survey were attributable to atopy. Some allergen-specific skin tests were not independently associated with asthma.

CLINICAL IMPLICATIONS

If atopy could be prevented or reversed, or its effect on asthma blocked, then a large percentage of asthma cases in the US population could be prevented.

Health effects of indoor nitrogen dioxide and passive smoking on urban asthmatic children

BACKGROUND

Nitrogen dioxide (NO(2)) and environmental tobacco smoke (ETS) have been associated with adverse respiratory effects.

OBJECTIVE

We sought to assess the effect of NO(2) and ETS on asthma morbidity among children in inner-city environments.

METHODS

Asthmatic children between the ages of 4 and 9 years had exposure to NO(2) and ETS measured by using Palmes tubes in the home and urinary cotinine. A baseline interview and telephone assessments at 3, 6, and 9 months evaluated health service use, asthma symptoms, and peak flow rates.

RESULTS

Gas stoves were present in 87.8% of 469 homes. The median level of indoor NO(2) was 29.8 ppb compared with the US national outdoor median of 18 ppb. Of 1444 children, 48% had urinary cotinine/creatinine ratios of greater than 30 ng/mg. The median level of the cotinine/creatinine ratio was 42.4 ng/mg in smoking homes compared with 18.0 ng/mg in nonsmoking homes. The relative risk for asthma symptoms with increased NO(2) exposure was 1.75 (95% CI, 1.10-2.78) in children who did not have positive skin test responses. Higher NO(2) exposure resulted in lower peak flows during colder months (relative risk, 1.46; 95% CI, 1.07-1.97). Higher ETS exposure in colder months was weakly associated with lower peak flows (relative risk, 1.21; 95% CI, 0.99-1.47). There was no effect of ETS exposure on symptoms or use of health care services.

CONCLUSION

Higher levels of indoor NO(2) are associated with increased asthma symptoms in nonatopic children and decreased peak flows.

CLINICAL IMPLICATIONS

Interventions to reduce NO(2) exposure, such as venting of gas stoves, might help reduce asthma morbidity.

Asthma and body weight change: a 20-year prospective community study of young adults

OBJECTIVE

There is increasing evidence for an association between asthma and body weight change. The objectives of these analyses were to examine the temporal relationships of this association and to explore the role of childhood depression as an explanatory factor.

METHODS

Data were derived from six subsequent semistructured interviews on health habits and health conditions from a single-age community study of 591 young adults followed up between ages 20 and 40 years.

RESULTS

Cross-sectionally (over the whole study period), asthma was significantly associated with obesity (odds ratio=3.9 [95% confidence interval 1.2, 12.2]). Multivariate longitudinal analyses revealed that asthma was associated with increased later weight gain and later obesity among women after controlling for potentially confounding variables, whereas weight gain and obesity were not associated with later asthma. A secondary analysis showed that depressive symptoms during childhood were associated with adult obesity and asthma, partially explaining the asthma-obesity comorbidity.

CONCLUSION

This study encourages further research on mechanisms underlying the asthma-obesity comorbidity, particularly on shared psychosocial factors operating during critical periods in childhood and adolescence that may influence the development and persistence of both obesity and asthma during adulthood.

Cost-effectiveness of a home-based environmental intervention for inner-city children with asthma

BACKGROUND

Exposure to indoor allergens contributes to increased asthma morbidity. The Inner-City Asthma Study, a randomized trial involving home environmental allergen and irritant remediation among children aged 6 through 11 years with moderate-to-severe asthma, successfully reduced asthma symptoms. A cost-effectiveness analysis can help stakeholders to evaluate the potential costs and benefits of adopting such a program.

OBJECTIVE

We sought to assess the cost-effectiveness of the environmental intervention of the Inner-City Asthma Study.

METHODS

Incremental cost-effectiveness ratios for a 2-year study period were calculated. Health outcome was measured as symptom-free days. Resource use measures included ambulatory visits, hospitalizations, and pharmaceutical use. CIs were obtained by using bootstrapping.

RESULTS

The intervention, which cost $1469 per family, led to statistically significant reductions in symptom days, unscheduled clinic visits, and use of beta-agonist inhalers. Over the year of the intervention and a year of follow-up, the intervention cost was $27.57 per additional symptom-free day (95% CI, $7.46-$67.42). Subgroup analysis showed that targeting the intervention to selected high-risk subgroups did not reduce the incremental cost-effectiveness ratio.

CONCLUSIONS

A targeted home-based environmental intervention improved health and reduced service use in inner-city children with moderate-to-severe asthma. The intervention is cost-effective when the aim is to reduce asthma symptom days and the associated costs.

Prevalences of positive skin test responses to 10 common allergens in the US population: results from the third National Health and Nutrition Examination Survey

BACKGROUND

Allergy skin tests were administered in the second and third National Health and Nutrition Examination Surveys (NHANES II and III) conducted in the United States from 1976 through 1980 and 1988 through 1994, respectively.

OBJECTIVES

This study estimated positive skin test response rates in NHANES III and identified predictors of one or more positive test responses. Comparisons with NHANES II were also made.

METHODS

In NHANES III, 10 allergens and 2 controls were tested in all subjects aged 6 to 19 years and a random half-sample of subjects aged 20 to 59 years. A wheal-based definition of a positive test response was used.

RESULTS

In NHANES III, 54.3% of the population had positive test responses to 1 or more allergens. Prevalences were 27.5% for dust mite, 26.9% for perennial rye, 26.2% for short ragweed, 26.1% for German cockroach, 18.1% for Bermuda grass, 17.0% for cat, 15.2% for Russian thistle, 13.2% for white oak, 12.9% for Alternaria alternata, and 8.6% for peanut. Among those with positive test responses, the median number of positive responses was 3.0. Adjusted odds of a positive test response were higher for the following variables: age of 20 to 29 years, male sex, minority race, western region, old homes, and lower serum cotinine levels. For the 6 allergens common to NHANES II and III, prevalences were 2.1 to 5.5 times higher in NHANES III.

CONCLUSIONS

The majority of the US population represented in NHANES III was sensitized to 1 or more allergens. Whether the higher prevalences observed in NHANES III reflect true changes in prevalence or methodological differences between the surveys cannot be determined with certainty.

Transient environmental exposures on the developing immune system: implications for allergy and asthma

PURPOSE OF REVIEW

Early environmental exposures have been extensively studied as potential causes of the observed increase in allergic disease over time. Transient fetal or neonatal exposures in particular are of interest in that they may occur during critical windows of immune system development. Due to the tremendous complexity of variables in early life, as well as the difficulty in randomizing many interventions, it is very difficult to properly study these exposures. Some progress, however, has been made and some more candidates for study may be emerging. Of particular interest are micronutrients, whose ever-changing use and immunomodulatory capabilities make them prime targets for study.

RECENT FINDINGS

New risk factors for atopic disease have emerged from the pool of early life interventions, such as caesarian section, prolonged labor and infant multivitamin supplementation. Data are emerging regarding micronutrient status and supplementation and their effects on the developing immune system and risk for allergic disease. Clinical trials have yet to demonstrate much causality but, in some cases, it is too early to make any judgments.

SUMMARY

The gold standard of randomized clinical trials has not borne out a number of proposed early-life allergic risk factors, while other trials are too incomplete to draw any conclusions so far. Properly designed studies for other risk factor interventions may still be achievable, provided that there is a proper understanding of the interventions, populations and outcomes.

Asthma and panic in young adults: a 20-year prospective community study

RATIONALE

Psychologic factors are increasingly recognized to influence the onset and course of asthma. Previous cross-sectional community-based studies have provided evidence for a relatively specific association between asthma and panic.

OBJECTIVES

To examine concurrent and longitudinal associations between asthma and panic in young adults.

MEASUREMENTS AND MAIN RESULTS

Prospective community-based cohort study of young adults (n = 591) followed between ages 19 and 40. Information was derived from six subsequent semistructured diagnostic interviews conducted by professionals. Cross-sectionally (over the whole study period), asthma was more strongly associated with panic disorder (odds ratio [OR] = 4.0; 95% confidence interval [CI], 1.7, 9.3) than with any panic, which included panic disorder and panic attacks (OR = 2.1; 95% CI, 1.1, 4.5). Longitudinally, after adjusting for potentially confounding variables, active asthma predicted subsequent panic disorder (OR = 4.5; 95% CI, 1.1, 20.1), and the presence of panic disorder predicted subsequent asthma activity (OR = 6.3; 95% CI, 2.8, 14.0). Asthma predicted any panic (OR = 2.7; 95% CI, 1.1, 7.1), whereas any panic did not predict subsequent asthma activity. Associations were stronger in smokers than in nonsmokers, and stronger in women than in men. Smoking, early-childhood anxiety, and a family history of allergy were important confounders of the asthma-panic association.

CONCLUSIONS

This is the first long-term follow-up study on asthma and panic. It showed dose-response-type relationships between panic and asthma, and bidirectional longitudinal associations between the two conditions. It provided evidence for familial factors and smoking as possible shared etiologic explanations.

Postoperative adverse events in teaching and nonteaching hospitals

BACKGROUND AND OBJECTIVES

With the recent attention on quality of care and residency training, teaching hospitals are coming under greater scrutiny. Despite several studies, there is still no consensus on whether teaching hospitals deliver higher quality of care than nonteaching hospitals.

METHODS

This was a retrospective cross-sectional study, using national hospital data. The sample consisted of 3,818 acute care hospitals in the National Inpatient Sample from 1990-1996. The quality indicators were postoperative adverse events, including venous thrombosis/pulmonary embolism (DVT/PE), pulmonary compromise, pneumonia, and urinary tract infection (UTI). Hospitals were classified as major teaching, other teaching, and nonteaching. Quality indicator rates of hospital types were compared and multivariate regression performed to control for specific hospital characteristics.

RESULTS

Teaching hospitals had higher rates of postoperative DVT/PE and pulmonary compromise but lower rates of UTI, compared with nonteaching hospitals. In the multivariate analysis, teaching hospitals were more likely to have higher postoperative DVT/PE rates, and other teaching hospitals had higher rates of pulmonary compromise and UTI. Postoperative pneumonia rates were higher in major teaching hospitals than nonteaching hospitals.

CONCLUSIONS

Rates of postoperative adverse events were higher in teaching hospitals compared to nonteaching hospitals. These findings suggest that quality of care, as measured by postoperative adverse events, may not be higher in teaching hospitals.

Understanding the seasonal pattern of childhood asthma: results from the National Cooperative Inner-City Asthma Study (NCICAS)

OBJECTIVE

To contrast the seasonal patterns of asthma symptoms and utilization and determine the impact of allergen sensitivity, environmental tobacco smoke (ETS) exposure, and air pollution on the seasonal patterns of asthma.

STUDY DESIGN

Participants in the National Cooperative Inner-City Asthma Study (NCICAS) were tracked for approximately 4 years after allergen skin testing and determination of exposure to ETS. Air pollution data were obtained from EPA monitoring sites in NCICAS cities.

RESULTS

Asthma symptoms (wheeze) and health care utilization (unscheduled visits and hospitalization) had similar seasonal patterns, with low points during the summer months of June through August and a distinct autumn peak beginning in September. Seasonal patterns were similar among children with no allergen skin test reactivity, those reactive only to indoor allergens, and those reactive to outdoor allergens. ETS exposure, whether defined by self-report or urinary cotinine/creatinine ratio, was not related to the observed seasonal patterns. Among the pollutants evaluated, only the seasonal pattern of SO(2) coincided with that of asthma morbidity.

CONCLUSIONS

Atopy, ETS, and most air pollutants do not appear to contribute to the distinct asthma seasonal pattern. On a population level, changes in symptoms are mirrored by changes in utilization.

The cost-effectiveness of an inner-city asthma intervention for children

BACKGROUND

Comprehensive management efforts to reduce asthma morbidity among children in urban areas with high levels of poverty and large minority populations have been inconclusive. The National Cooperative Inner-City Asthma Study (NCICAS) demonstrated improved symptom outcomes but did not evaluate cost-effectiveness in this population.

OBJECTIVE

We sought to examine the incremental cost-effectiveness of a comprehensive social worker-based education program and environmental control in children with asthma stratified by baseline level of asthma control.

METHODS

We performed a prospective cost-effectiveness analysis alongside a randomized trial. A total of 1033 children and their families residing in 8 inner-city urban areas in the United States were enrolled in the NCICAS. Outcomes included symptom-free days, cost per symptom-free day gained, and annual costs of asthma morbidity compared by baseline symptom control, previous hospitalization, and previous unscheduled physician visits.

RESULTS

The NCICAS intervention significantly reduced asthma symptoms. First-year intervention costs were 245 US dollars higher for the intervention children compared with those receiving usual care. There were no additional intervention-related costs during the second year. When compared with usual care, the intervention improved outcomes at an average additional cost of 9.20 US dollars per symptom-free day gained (95% CI, -12.56 to 55.29 US dollars). The intervention was cost saving in 3 strata of children with increasing asthma severity.

CONCLUSIONS

A multifaceted asthma intervention program reduced symptom days and was cost-effective for inner-city children with asthma. In children with more severe disease, the intervention was substantially more effective and reduced costs compared with that seen in control children. Organizations serving this population should consider this strategy as part of a comprehensive disease-management program for asthma.

Nurse staffing and postsurgical adverse events: an analysis of administrative data from a sample of U.S. hospitals, 1990-1996

OBJECTIVE

To examine the impact of nurse staffing on selected adverse events hypothesized to be sensitive to nursing care between 1990 and 1996, after controlling for hospital characteristics.

DATA SOURCES/STUDY SETTING

The yearly cross-sectional samples of hospital discharges for states participating in the National Inpatient Sample (NIS) from 1990-1996 were combined to form the analytic sample. Six states were included for 1990-1992, four states were added for the period 1993-1994, and three additional states were added in 1995-1996.

STUDY DESIGN

The study design was cross-sectional descriptive.

DATA COLLECTION/EXTRACTION METHODS

Data for patients aged 18 years and older who were discharged between 1990 and 1996 were used to create hospital-level adverse event indicators. Hospital-level adverse event data were defined by quality indicators developed by the Health Care Utilization Project (HCUP). These data were matched to American Hospital Association (AHA) data on community hospital characteristics, including registered nurse (RN) and licensed practical/vocational nurse (LPN) staffing hours, to examine the relationship between nurse staffing and four postsurgical adverse events: venous thrombosis/pulmonary embolism, pulmonary compromise after surgery, urinary tract infection, and pneumonia. Multivariate modeling using Poisson regression techniques was used.

PRINCIPAL FINDINGS

An inverse relationship was found between RN hours per adjusted inpatient day and pneumonia (p < .05) for routine and emergency patient admissions.

CONCLUSIONS

The inverse relationship between pneumonia and nurse staffing are consistent with previous findings in the literature. The results provide additional evidence for health policy makers to consider when making decisions about required staffing levels to minimize adverse events.

Impact of site of care, race, and Hispanic ethnicity on medication use for childhood asthma

OBJECTIVE

To understand the importance of source of care and other factors that influence differences in asthma medication use by race and Hispanic ethnicity.

METHODS

The Childhood Asthma Severity Study provided 12-month, retrospective, parent-reported questionnaire data on a monthly basis for children ages </=12 years in a community sample of 1002 children and their families from Connecticut and Massachusetts. Medications considered included cromolyn, beta2-agonist, inhaled steroids, anticholinergics, theophylline, and systemic steroids. Information was available on demographics, insurance status, symptom severity, primary care contact, and provider practice types.

RESULTS

Black and Hispanic children received fewer beta2-agonists, and Hispanic children received fewer inhaled steroids than white children after adjusting for patients' race, age, gender, insurance status, symptom severity, number of primary care visits for asthma, number of urgent visits to the regular provider, family income, maternal education, and site of care. When multivariate analyses were restricted to patients in private practice, the significant association between Hispanic ethnicity and low inhaled steroid use persisted, whereas differences in beta2-agonist use by race and ethnicity changed little but became nonsignificant.

CONCLUSION

Even within private practices, patients' race and ethnicity are associated with clinician nonadherence to national guidelines. Programs to eliminate these disparities will need both to focus on site of care and to intervene at the provider and patient levels to be successful.

Sociodemographic correlates of indoor allergen sensitivity among United States children

BACKGROUND

Exposure to indoor allergens is associated with asthma morbidity. Nationally, asthma morbidity disproportionately affects socially disadvantaged populations, but it is unclear whether exposure to indoor allergens follows a similar pattern.

OBJECTIVE

We sought to examine the national prevalences and demographic correlates of sensitivity to indoor allergens related to asthma.

METHODS

Analysis of a cross-sectional survey of a representative sample of 4164 United States children aged 6 to 16 years who participated in allergen testing in the Third National Health and Nutrition Examination Survey from 1988 to 1994 was performed. The main outcome measures were sensitivity reactions to cockroach, dust mite, cat, and Alternaria alternata, as measured via skin prick testing.

RESULTS

Multivariate models, including sex, age, race-ethnicity, education, poverty, family history, region of country, housing age, crowding, and urban residence, revealed significant racial-ethnic disparities in sensitivity. Compared with white children, African American children had higher odds ratios (ORs) of cockroach or dust mite sensitivity (cockroach OR, 2.5 [95% CI, 1.9-3.2]; dust mite OR, 1.3 [95% CI, 1.0-1.7]), as did Mexican American children (cockroach OR, 1.9 [95% CI, 1.3-2.8]; dust mite OR, 1.6 [95% CI, 1.2-2.2]). African American children also had significantly higher odds of sensitivity to A alternata (OR, 2.1 [95% CI, 1.5-2.8]).

CONCLUSIONS

African American and Mexican American children are substantially more likely than white children to be sensitized to allergens important in asthma. Differences in indoor allergen sensitivity are consistent with racial differences in asthma morbidity. Along with other data, these findings suggest that racial disparities in housing, community, or both environmental factors play a role in determining national patterns of asthma morbidity.