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2004 Progress Report: The Epidemiology of Susceptibility to Airborne Particulates and Allergens to Asthma in African Americans
EPA Grant Number: R832139C001Subproject: this is subproject number 001 , established and managed by the Center Director under grant R832139
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
Center: Johns Hopkins Center for Childhood Asthma in the Urban Environment
Center Director: Breysse, Patrick
Title: The Epidemiology of Susceptibility to Airborne Particulates and Allergens to Asthma in African Americans
Investigators: Diette, Greg
Institution: Johns Hopkins University
EPA Project Officer: Fields, Nigel
Project Period: November 1, 2003 through October 31, 2008 (Extended to October 31, 2010)
Project Period Covered by this Report: November 1, 2003 through October 31, 2004
RFA: Centers for Children's Environmental Health and Disease Prevention Research (2003)
Research Category: Children's Health , Health Effects
Description:
Objective:The long-range goal of the epidemiologic study is to examine the genetic basis of asthma in African Americans with specific attention to genetic modifiers involved in the enhanced susceptibility of certain patients to particulate matter (PM) and allergens. Our strategy is to employ high-throughput genomic technologies to examine the patterns of gene expression to identified candidate genes and the genetic basis for polymorphisms in genes, which explain susceptibility to PM in an inner-city African American population with asthma.
The specific objectives are to: (1) obtain and prioritize candidate genes for susceptibility to airborne PM through gene expression profiling in human CD4+ T-lymphocytes; (2) identify polymorphisms in candidate genes associated with susceptibility to PM exposures in asthma and with asthma severity; and (3) identify polymorphisms in candidate genes associated with an interactive effect of cockroach allergen and PM10 exposures in severe asthma.
An important secondary goal was to complete a case control study of home environments in inner-city children with and without asthma and the nested longitudinal followup of the asthmatic cases. The original goals and objectives of this study were to: (1) characterize and compare exposure to allergens and air pollutants among inner-city children with and without asthma; (2) in a subset of homes, characterize the within-home temporal variability in air pollution and allergen exposure; (3) estimate the occurrence of respiratory morbidity among inner-city children with asthma; (4) study environmental and hereditary determinants of childhood asthma; (5) assess independent and joint effects of exposure to indoor allergens and indoor air pollution on respiratory morbidity in children with asthma; (6) characterize current use of environmental control practices among inner-city children with asthma; (7) identify barriers through the use of guidelines on environmental control practices among primary care providers caring for inner-city children with asthma; (8) assess the differential impact of indoor and outdoor air pollution among asthmatic and nonasthmatic homes; and (9) understand the relative contribution of different structural, financial, and personal barriers to use of recommended environmental control practices for children with asthma. Once completed, the data needed to be cleaned, a database constructed, and outcome analyses begun.
Progress Summary:Identification and Recruitment of Asthma and Control Subjects
Our recruitment goals of 150 children with asthma and 150 control children without asthma were accomplished by November 2004. To date, we also have completed successfully the planned 3-month (78%) and 6-month (87%) followups in the children enrolled in the cohort study (children with asthma).
Identification and Recruitment of Primary Care Physicians
The primary care physicians of the children enrolled in our study also are study subjects. We assess their compliance with national asthma guidelines for use of environmental control practices, as well as identify barriers to their use of these practices. We have identified 30 physicians who care for the children with asthma who are enrolled in our study, 14 of whom have completed the mailed survey so far.
We have performed preliminary analyses on the children enrolled. Among enrolled children without asthma, the mean age was 3.8 years (SD 1.5 years), 45 percent were male, 99 percent were African American, and 3.5 percent were Hispanic. About one-half of the parents reported a total household income of less than $25,000 per year. Among the children with asthma enrolled in the study, 57 percent were male, 94 percent African American, and 1.4 percent Hispanic; 88 percent had Medicaid insurance. There was substantial evidence of poor asthma control in these children: 36 percent had one or more emergency department visits for asthma in the previous 3 months, and 56 percent had one or more days of wheezing in the prior 2 weeks. Fifty-nine percent had one or more nights of awakening from asthma in the prior 2 weeks. Parents of asthmatics reported that they had seen roaches in their home (43%) and 54 percent had cats, 43 percent dogs, and 82 percent had seen evidence of mice. The mean age of asthma subjects was 4.17 years. Among asthmatics, 57 percent were male. Thirty-five percent of parents of asthmatics had not graduated from high school, and only 37 percent of parents were working full time. Approximately 29 percent of families of asthmatics had a total income that was less than $20,000 annually. Among control subjects, the mean age was 3.84 years, 45 percent were male, 35 percent had parents who had not graduated from high school, 34 percent of parents were working full time, and 35 percent had household income less than $20,000 annually. Among the children with asthma, 58 percent are mild intermittent, 17 percent mild persistent, and 25 percent moderate or severe persistent, as characterized by National Heart, Lung, and Blood Institute (NHLBI) guidelines. Forty-five percent of asthmatic children are skin test positive to cockroach antigen (Bla g 1). The median level of bedroom Bla g 1 is 6.0 U/g, a value slightly higher than seen in the intervention study. Median bedroom level of PM2.5 was 28.0 g/m3, and median PM10 level was 40.6 g/m3. Children with the greatest symptom severity had the highest levels of bedroom PM. For example, 38 percent of children in the highest quartile of PM2.5 values had moderate/severe persistent asthma versus only 21 percent of those in the lowest quartile. Likewise, 28 percent of children in the highest quartile of PM10 had moderate/severe persistent asthma versus only 17 percent in the lowest quartile. Asthmatic children in this study are reevaluated at 3 and 6 months (parent survey and home environmental assessment).
Preliminary analysis of the physician-reported data shows that adherence to environmental control measures recommended by the 1997 NHLBI asthma guidelines is low. Although 80 percent of physicians ask all parents about exposure to tobacco smoke, only 60 percent ask about pets, 20 percent about dust mites, and 10 percent about indoor molds. None of the physicians routinely order skin testing for allergens, and only 10 percent advise their asthma patients to stay indoors on high ozone days. Barriers to the use of the guidelines, based on a conceptual model of problems with awareness of, agreement with, and ability to use the guidelines, were apparent for all studied guideline recommendations. For example, no physicians reported being very or extremely familiar with the NHLBI guidelines, and only 50 percent had a copy of them. Only 40 percent of physicians agree that children should undergo skin testing to assess sensitivity to seasonal allergens, even though all agree that physicians should help parents to reduce allergen exposure. Citing ability barriers to counseling parents to reduce inhaled allergen exposure for children, 90 percent of physicians reported a lack of time during a patient visit, 70 percent a lack of educational materials, 60 percent indicated they were inadequately trained, and 50 percent reported not having adequate support staff for these functions. Outcomes expectancy was low, with only 30 percent of physicians believing that there would be a modest or large benefit to counseling patients to reduce exposure to pets, dust mites, and cockroaches.
Findings, Relevance to Field
Our findings have several implications to the field of asthma. First, to our knowledge they are the first studies to demonstrate that ambient particulates can directly induce the symptoms of asthma. Second, our finding that particulates induce complement component 3 activation may provide a potential mechanism by which particulates induce airway hyperresponsiveness and inflammation as well as provide a potential therapeutic target.
Future Activities:We plan to approach the 150 asthmatic children who have completed the original case-control study to obtain genetic samples. The next population to be approached will be those 100 families who participated in the Intervention Clinical Trial (see EPA Agreement No. R832139C002). These children and their families have given permission to be contacted for future studies in asthma. Environmental measures already have been completed on the majority of these children.
Journal Articles on this Report : 10 Displayed | Download in RIS Format
| Other subproject views: | All 35 publications | 35 publications in selected types | All 35 journal articles |
| Other center views: | All 103 publications | 103 publications in selected types | All 100 journal articles |
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Alberg AJ, Diette GB, Ford JG. Invited commentary: Attendance and absence as markers of health status—the example of active and passive cigarette smoking. American Journal of Epidemiology 2003;157(10):870-873. |
R832139 (2004) R832139 (2005) R832139C001 (2004) |
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Bartlett SJ, Krishnan JA, Riekert KA, Butz AM, Malveaux FJ, Rand CS. Maternal depressive symptoms and adherence to therapy in inner-city children with asthma. Pediatrics 2004;113(2):229-237. |
R832139 (2004) R832139 (2005) R832139C001 (2004) |
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Diette GB, Krishnan JA, Wolfenden LL, Skinner EA, Steinwachs DM, Wu AW. Relationship of physician estimate of underlying asthma severity to asthma outcomes. Annals of Allergy, Asthma & Immunology 2004;93(6):546-552. |
R832139 (2004) R832139 (2005) R832139C001 (2004) |
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Huang I-C, Frangakis C, Dominici F, Diette GB, Wu AW. Application of a propensity score approach for risk adjustment in profiling multiple physician groups on asthma care. Health Services Research 2005;40(1):253-278. |
R832139 (2004) R832139 (2005) R832139C001 (2004) R832139C001 (2006) |
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Matsui EC, Krop EJM, Diette GB, Aalberse RC, Smith AL, Eggleston PA. Mouse allergen exposure and immunologic responses: IgE-mediated mouse sensitization and mouse-specific IgG and IgG4 levels. Annals of Allergy, Asthma & Immunology 2004;93(2):171-178. |
R832139 (2004) R832139 (2005) R832139C001 (2004) |
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Okelo SO, Wu AW, Krishnan JA, Rand CS, Skinner EA, Diette GB. Emotional quality-of-life and outcomes in adolescents with asthma. Journal of Pediatrics 2004;145(4):523-529. |
R832139 (2004) R832139 (2005) R832139C001 (2004) |
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Skinner EA, Diette GB, Algatt-Bergstrom PJ, Nguyen TT, Clark RD, Markson LE, Wu AW. The Asthma Therapy Assessment Questionnaire (ATAQ) for children and adolescents. Disease Management 2004;7(4):305-313. |
R832139 (2004) R832139 (2005) R832139C001 (2004) |
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Swartz LJ, Callahan KA, Butz AM, Rand CS, Kanchanaraksa S, Diette GB, Krishnan JA, Breysse PN, Buckley TJ, Mosley AM, Eggleston PA. Methods and issues in conducting a community-based environmental randomized trial. Environmental Research 2004;95(2):156-165. |
R832139 (2004) R832139 (2005) R832139C001 (2004) |
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Wolfenden LL, Diette GB, Krishnan JA, Skinner EA, Steinwachs DM, Wu AW. Lower physician estimate of underlying asthma severity leads to undertreatment. Archives of Internal Medicine 2003;163(2):231-236. |
R832139 (2004) R832139 (2005) R832139C001 (2004) |
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Yurk RA, Diette GB, Skinner EA, Dominici F, Clark RD, Steinwachs DM, Wu AW. Predicting patient-reported asthma outcomes for adults in managed care. The American Journal of Managed Care 2004;10(5):321-328. |
R832139 (2004) R832139 (2005) R832139C001 (2004) |
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childhood asthma, inner-city children, allergens, African Americans, particulate matter, PM, wheezing, children’s health,
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HUMAN HEALTH, Air, Scientific Discipline, Health, RFA, PHYSICAL ASPECTS, Health Effects, Health Risk Assessment, Physical Processes, Epidemiology, particulate matter, Allergens/Asthma, Genetics, minority children, allergens, children's health, cockroaches, air toxics, respiratory, minorities, airway variablity, indoor-outdoor relationships, air pollution, airborne pollutants, children, epidemiological studies, asthma morbidity, exposure, long term exposure, asthma triggers, asthma, human exposure, morbidity, PM
Progress and Final Reports:
Original Abstract
2005 Progress Report
2006 Progress Report
2007 Progress Report
Main Center Abstract and Reports:
R832139 Johns Hopkins Center for Childhood Asthma in the Urban Environment
Subprojects under this Center: (EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
R832139C001 The Epidemiology of Susceptibility to Airborne Particulates and Allergens to Asthma in African Americans
R832139C002 A Randomized Controlled Trial of Behavior Changes in Home Exposure Control
R832139C003 Mechanisms of Particulate-Induced Allergic Asthma
R832139C004 Dendritic Cell Activation by Particulate Matter and Allergen