Food allergen sensitization in inner-city children with asthma

BACKGROUND: Asthma continues to be an increasing cause of morbidity in the pediatric population, and studies have shown an association between food sensitivity and asthma. OBJECTIVE: We investigated the degree of food allergen sensitization in inner-city patients with asthma. METHODS: Five hundred four random serum samples from the National Cooperative Inner City Asthma Study were evaluated for specific IgE (UniCap) to 6 common food allergens (egg, milk, soy, peanut, wheat, and fish). Statistical analyses were performed to determine food sensitization prevalence and its association with asthma morbidity. RESULTS: Forty-five percent of patients had evidence of sensitization (food-specific IgE > or = 0.35 kU/L) to at least 1 food. Nineteen percent had IgE levels at > or = 50% positive predictive value for clinical reactivity to at least 1 food, with 4% of patients having levels > 95% positive predictive value for food allergy. Children sensitized to foods had higher rates of asthma hospitalization (P < .01) and required more steroid medications (P = .025). Sensitization to foods also correlated with sensitization to more indoor and outdoor aeroallergens (P < .001). CONCLUSION: Food allergen sensitization is highly prevalent in the inner-city population with asthma, and it is associated with increased asthma healthcare and medication use. Therefore, food allergen sensitivity may be a marker for increased asthma severity.     

Addressing issues of asthma in inner-city children

For children living in the inner city, asthma tends to be more frequent and severe. Although the causes for this heightened severity of asthma are not clearly established, environmental allergens likely play a major role. To characterize, understand, and treat children with asthma living in the inner city better, the National Institutes of Allergy and Infectious Diseases of the National Institutes of Health established an Inner City Asthma Program in 1991. Over the past 15 years, 3 separate inner-city asthma research networks have been formed and funded by this institute. The work from these programs has led to important observations including evidence that environmental allergens, particularly cockroach, are important for sensitization and severity of asthma of the affected children. Furthermore, reductions in the allergen load can lead to improved asthma control. The most recent program, the Inner City Asthma Consortium, was formed in 2002 with a goal to develop immune-based therapy for children with asthma in the inner city and to determine mechanisms of these therapies as well as immunopathogenesis of asthma in these high-risk children. This article reviews these programs and how they have begun the effort to understand and treat children with asthma who live in inner cities better and what their findings mean in relationship to unique features of asthma in inner city children.     

Mouse allergen-specific antibody responses in inner-city children with asthma

BACKGROUND: Although mouse allergen exposure is common in inner-city homes, little is known about the relationships between exposure and humoral immune responses to mouse allergen in this population. OBJECTIVE: To examine relationships between mouse allergen exposure and allergen-specific IgE and IgG responses in inner-city children with asthma. METHODS: Inner-city children with asthma underwent skin testing and venipuncture for determination of mouse allergen-specific IgE and IgG levels. Settled dust samples were collected from their homes for allergen analysis. RESULTS: The study population (n = 112) was predominantly African American (92%) with a mean age of 4.4 years. The prevalence rate of mouse sensitization was 25% and did not consistently increase with increasing Mus m 1 levels. Instead, the prevalence rate was lowest among those exposed to <2 microg/g, increased among those exposed to 2-7.9 microg/g and 8-29.9 microg/g, and then decreased among participants exposed to >29.9 microg/g (14%, 20%, 40%, and 28%, respectively). Similarly, the prevalence rates of mouse allergen-specific IgG and IgG(4) did not increase across increasing exposure categories. Mouse allergen-specific IgG and IgG(4) were strongly associated with IgE sensitization (odds ratios [95% CI], 82.8 [20.5-334.4] and 50.4 [14.0-181.7], respectively). CONCLUSION: High-level exposure to mouse allergen in children may be associated with attenuated humoral responses of all isotypes rather than selective attenuation of IgE. CLINICAL IMPLICATIONS: Protection against allergic sensitization by high-dose allergen exposure may not be mediated by preferential production of IgG over IgE.     

Airborne mouse allergen in the homes of inner-city children with asthma

BACKGROUND: Airborne mouse allergen has not previously been measured in inner-city homes, and its relationship to settled dust mouse allergen levels is unknown. OBJECTIVE: To quantify airborne and settled dust Mus m 1 levels in homes of inner-city patients with asthma and to identify risk factors for mouse allergen exposure. METHODS: One hundred inner-city school-age children with asthma in Baltimore underwent skin testing to a panel of aeroallergens, and their homes were inspected by a trained technician. Air and settled dust were sampled in the child's bedroom. Mus m 1, particulate matter smaller than 10 microns (PM 10 ), and particulate matter smaller than 2.5 microns were quantified in air samples, and Mus m 1 was quantified in settled dust samples. RESULTS: Mus m 1 was detected in settled dust samples from 100% of bedrooms. Airborne mouse allergen was detected in 48 of 57 (84%) bedrooms, and the median airborne mouse allergen concentration was 0.03 ng/m 3 . The median PM 10 concentration was 48 microg/m 3 . Airborne and settled dust mouse allergen levels were moderately correlated ( r = .52; P < .0001), and airborne Mus m 1 and PM 10 levels were weakly correlated ( r = .29; P = .03). Having cracks or holes in doors or walls, evidence of food remains in the kitchen, and mouse infestation were all independently associated with having detectable airborne mouse allergen. CONCLUSION: Airborne mouse allergen concentrations in many inner-city homes may be similar to those found in animal facilities, where levels are sufficiently high to elicit symptoms in sensitized individuals. Exposed food remains, cracks and holes in doors or walls, and evidence of mouse infestation appear to be risk factors for having detectable airborne Mus m 1.     

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.     

Endotoxin exposure in inner-city schools and homes of children with asthma

BackgroundEndotoxins are stimulators of the immune system and, despite their potential to protect against allergy, have been associated with early wheezing and asthma morbidity.ObjectiveTo compare inner-city school endotoxin exposure with home endotoxin exposure in children with asthma.MethodsStudents with asthma were recruited from 12 urban elementary schools. Settled and airborne dust samples, linked to enrolled students, were collected from school classrooms, gymnasiums, and cafeterias twice during the academic year. For comparison, settled dust was collected once from the bedrooms of students with asthma.ResultsTwo hundred twenty-nine school settled dust samples and 118 bedroom settled dust samples were collected and analyzed for endotoxin. The median endotoxin concentration for school samples was 13.4 EU/mg (range, 0.7–360.7 EU/mg) and for home samples was 7.0 EU/mg (range = LLOD–843.0 EU/mg). The median concentration within each individual school varied from 6.6 EU/mg to 24.0 EU/mg. One hundred four students with asthma had matched classroom and bedroom endotoxin exposure measurements performed in the same season and demonstrated significantly higher concentrations of endotoxin in the students' classrooms (mean log value, 1.13 vs 0.99, P = .04). The median of the classrooms was 12.5 EU/mg compared with their bedrooms, with a median of 7.0 EU/mg. Within the school environment, no significant difference was seen between the fall and spring samples (mean log value 1.14 vs 1.09; P = .35).ConclusionInner-city children with asthma were exposed to higher concentrations of endotoxin in their classrooms as compared with their bedrooms. Further studies are needed to evaluate school endotoxin exposure as a factor in asthma morbidity.     

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.     

Environmental tobacco smoke exposure and nocturnal symptoms among inner-city children with asthma

BACKGROUND: Environmental tobacco smoke (ETS) is a frequent exposure and is linked to asthma among inner-city children. OBJECTIVE: We sought to examine the relationship among ETS exposure, select asthma symptoms, and consequences among inner-city children with asthma. METHODS: Data from interviews with primary caregivers of inner-city elementary school children with asthma were evaluated (n = 590). Caregiver reports of child asthma symptoms, exercise limitations, asthma management, health care use, and ETS exposure were examined. RESULTS: Smoking in the home was reported by 29.4% of primary caregivers. ETS exposure (yes/no) was not related to frequency of child nocturnal symptoms or other select asthma morbidity markers. However, among children exposed to ETS, the frequency and severity of child nocturnal symptoms were highest among children exposed to moderate-to-heavy levels of ETS. After controlling for child age, anti-inflammatory medication use, asthma primary care, and caregiver's education, exposure to higher levels of ETS was associated with nearly a 3-fold increase in nocturnal symptoms in children (odds ratio, 2.83; 95% CI, 1.22-6.55). CONCLUSION: Among elementary school inner-city children with asthma, exposure to higher levels of ETS was associated with increased frequency of nocturnal symptoms. Reducing the exposure of children with asthma to ETS should be a clear priority in developing effective asthma management plans for inner-city families.     

Novel computer-based assessment of asthma strategies in inner-city children.

BACKGROUND: Childhood asthma continues to be a growing medical concern in the United States, affecting > 17 million children in 1998. The mortality rate from asthma in children aged 5 to 14 years has nearly doubled, from 1.7 deaths per million to 3.2 deaths per million between 1980 and 1993. OBJECTIVE: To evaluate the use of artificial neural networks (ANNs) to rate problem-based strategies for asthma management in a defined population of children. METHODS: The participants in our study were recruited from a local inner-city medical facility in Los Angeles. The majority of participants had received the diagnosis of mild-to-moderate-persistent asthma. Each participant was given 10 asthma-based problems and asked to manage them. Each management decision and its order were entered into a database. This database was used to train an artificial neural network (ANN). The trained ANN was then used to cluster the various performances, and outputs were evaluated graphically. RESULTS: Three hundred five performances were analyzed through our trained neural network. Our ANN classified five major clusters representing different approaches to solving an acute asthma case. CONCLUSIONS: ANNs can build rich models of complex phenomena through a training and pattern-recognition process. Such networks can solve classification problems with ill-defined categories in which the patterns are deeply hidden within the data, and models of behavior are not well defined. In our pilot study, we have shown that ANNs can be useful in automating evaluation and improving our understanding of how children manage their asthma.     

Home intervention in the treatment of asthma among inner-city children.

BACKGROUND: In Atlanta, as in other major urban areas of the United States, asthma is a leading cause of school absenteeism, emergency department use, and hospitalization. Recent guidelines for asthma management recommend reducing exposure to relevant allergens, but neither the feasibility nor the efficacy of this form of treatment has been established for children living in poverty. OBJECTIVE: We sought to investigate allergen avoidance as a treatment for asthma among inner-city children. METHODS: One hundred four children with asthma living in the city of Atlanta were enrolled into a controlled trial of avoidance without being skin tested. The children were randomized to an active avoidance group, a placebo avoidance group, and a second control group for which no house visits occurred until the end of the first year. Avoidance included bed and pillow covers, hot washing of bedding, and cockroach bait. Eighty-five children completed the study, and the outcome was measured as unscheduled clinic visits, emergency department visits, and hospitalization for asthma, as well as changes in mite and cockroach allergen levels. RESULTS: There was a significant decrease in acute visits for asthma among children whose homes were visited (P < .001). However, there was no significant difference between the active and placebo homes either in the effect on asthma visits or in allergen concentrations. When the children with mite allergy were considered separately, there was a significant correlation between decreased mite allergen and change in acute visits (P < .01). The avoidance measures for cockroach allergen appeared to be ineffective, and the changes observed did not correlate with changes in visits. CONCLUSIONS: Applying allergen avoidance as a treatment for asthma among children living in poverty is difficult because of multiple sensitivities and problems applying the protocols in this environment. The current results demonstrate that home visiting positively influences the management of asthma among families living in poverty. Furthermore, the results for children with mite allergy strongly suggest that decreasing relevant allergen exposure should be an objective of treatment in this population.     

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 IgG₄ 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 SIgG₄ 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.