BACKGROUND. Current guidelines for asthma management emphasize the control of environmental irritants and allergens within the home. Understanding the prevalence of indoor home exposures within such a population may be important for any emergency department (ED) program that seeks to improve the quality of its asthma care and patient education.
OBJECTIVE. We sought to determine the prevalence of indoor home exposures in a cohort of children with moderate to severe asthma who were treated in an urban pediatric ED and to correlate these exposures with household income, prior asthma morbidity, health care utilization, and quality of life (QoL).
METHODS. We enrolled a cohort of children with chronic asthma who were 12 months through 17 years of age and who had at least one other unscheduled visit for asthma within the previous 6 months. Trained research assistants interviewed the children’s parent or guardian regarding the prevalence of home exposures to environmental tobacco smoke (ETS) and common allergens. In addition, data were collected on each patient’s prior asthma history, morbidity, health care utilization, medication use, and QoL.
RESULTS. Of the 488 eligible children enrolled, 60.0% were <6 years of age, 63.9% were male, 85.9% were black, 68.4% were publicly insured, and 51.8% had >3 ED visits in the previous 12 months. Home exposure to ETS and potential allergens was high. Exposure to cockroach allergen was significantly associated with household income. Coexistence of exposures was common: significantly more patients reporting ETS exposure also reported exposure to cockroach allergen and mold than those not reporting ETS exposure. Poorer QoL was significantly associated with cockroach exposure, although this effect was limited to those also exposed to ETS. Higher rates of unscheduled health care utilization and persistent asthma symptoms were not associated with exposures.
CONCLUSION. Additional investigation is necessary to clarify the role of exposure-avoidance measures as a component of ED-based interventions for asthma care.
A recent report from the Institute of Medicine1 found sufficient evidence for a causal relationship between exposure to environmental tobacco smoke (ETS) and exacerbations of asthma. Evidence is strong that exposure to ETS affects the morbidity and health care utilization of children with asthma.2–4 Indoor exposures to common allergens are also risk factors for the exacerbation of asthma.5–8 The same Institute of Medicine report found sufficient evidence for a causal relationship between indoor exposure to allergens produced by cockroaches, cats, dogs, house dust mites, and mold and worsening of asthma.
Current guidelines for asthma management from the National Heart, Lung, and Blood Institute (NHLBI)9 and the American Academy of Allergy, Asthma and Immunology10 therefore emphasize the control of exposure to ETS and indoor allergens as a crucial component of asthma management within a coordinated program of longitudinal care with a primary care provider. Unfortunately, however, disadvantaged urban minority children with asthma seek much of their care in emergency departments (EDs).11–13 In fact, for many inner-city children, the ED is the primary source of their asthma care,14 yet little is known about the role that the urban ED can play in assessing and reducing environmental exposures. Understanding the nature of indoor home exposures within a population that relies heavily on the ED for asthma care may be important for improving ED asthma care.
Our objective with this analysis, therefore, is to describe the prevalence of parental report of home exposure to ETS and potential allergens in a cohort of children with moderate to severe asthma and a history of high ED recidivism for asthma. We also explore associations of exposures with household income and whether indoor environmental exposures are associated with higher asthma health care utilization and recent asthma morbidity.
Data analyzed here were collected from a cohort of patients prospectively recruited as part of a randomized clinical trial that enrolled children presenting for acute asthma care in the ED at Children’s National Medical Center (CNMC) in Washington, DC, from April 2002 until January 2004. CNMC is an urban, tertiary care pediatric medical center with an ED volume of 72778 visits in 2003. Of these visits, 4482 (6.1%) included a primary discharge diagnosis of asthma among patients aged 12 months to 17 years, inclusive.
This study was approved by the CNMC Institutional Review Board. The parent or guardian provided informed consent, and participants >6 years old provided assent.
Trained research assistants recruited subjects among those who presented with respiratory complaints. Inclusion criteria included all of the following: (1) age between 12 months and 17 years, inclusive; (2) prior physician-diagnosed asthma; (3) ≥1 other unscheduled visit for asthma in the previous 6 months and/or ≥1 hospitalization for asthma in the previous 12 months; (4) a parent or guardian available for interview; (5) residence in Washington, DC, or a contiguous Maryland county; and (6) required ≥3 doses of nebulized albuterol in the ED at the time of enrollment.
Exclusion criteria included (1) significant medical comorbidities affecting the cardiorespiratory system; (2) a visit to an allergist or pulmonologist in the previous 6 months; (3) ≥2 of the following: a current written asthma medical action plan, current use of >1 controller medication, or a scheduled visit for asthma care with the primary care provider in the previous 2 weeks; (4) enrollment in another asthma research study; (5) unavailability for telephone follow-up; or (6) primary language other than English or Spanish.
The research assistants administered a baseline questionnaire to the child’s parent or guardian. This measure assessed the presence of ETS and multiple potential indoor allergens within the child’s principal residence. It also assessed patient and family demographics, past asthma history, asthma severity classification by the criteria of the NHLBI,9 asthma quality of life (QoL), and history of health care utilization for asthma. QoL was scored through the use of a measure developed and validated for pediatric asthma.15,16
Exposure to ETS and potential allergens was based on the caregiver report. ETS exposure was defined as someone currently living in the child’s home who smokes cigarettes. Cockroach exposure was defined by the caregiver report of seeing cockroaches in the home in the previous month. Mold exposure was defined as the caregiver noticing mold or dampness in the home in the previous month. Dust mite exposure was defined by the presence of a carpet in the room where the child sleeps and/or stuffed animals on the child’s bed. In addition, we noted if a dog or cat lived in the home.
Descriptive analyses estimated the relative frequency of participants according to demographic, socioeconomic, and clinical characteristics. The adjusted odds ratios (ORs) with 95% confidence intervals (CIs) for environmental exposures were then estimated by using multiple logistic regression with covariables including age, gender, and race/ethnicity and with stratification for household income and then ETS exposure. These methods were also used to estimate the adjusted relative risks (RRs) of greater than the median number of unscheduled medical visits, of persistent asthma symptoms, and of less than median scores for 3 indicators of QoL. For the latter analyses, adjustment was made for the sociodemographic variables listed above as well as for medical care indicators and season of enrollment. Finally, posthoc secondary analysis was performed to examine the association between ETS exposure and allergen exposure.
The research assistants screened 2791 patients with a chief complaint of respiratory symptoms. Of these, 521 (18.7%) were eligible for enrollment and 490 (94.0%) were enrolled. Two enrolled patients were subsequently excluded for enrollment violations, which left 488 patients available for analysis. Patients were enrolled in the following windows: 65% between 8 am and 4 pm, 18% between 4 pm and midnight, and 17% between midnight and 8 am. Ten percent of the patients were enrolled on a Saturday or Sunday.
As shown in Table 1, patients were overwhelmingly minority and low income. Just under 25% reported using inhaled corticosteroid medication in the past month. More than half had visited the ED >3 times in the past year, and 30.3% had been hospitalized for asthma in the previous year. Despite this, 40.6% of the children were classified as having mild intermittent asthma according to NHLBI criteria.9
Reported prevalence of exposure to ETS and potential allergens in the home was high in this cohort of patients, as shown in Table 2. Exposure to cockroach allergen was significantly higher in lower-income households, whereas exposure to ETS, dog/cat, mold, and dust mites did not differ between the highest and lowest income levels.
The prevalence of combined indoor exposure to ETS and potential allergens is shown in Table 3. Exposure to ETS was significantly associated with exposure to both cockroach allergen and mold (cockroach: 34.0% vs 23.7% [OR: 1.66; 95% CI: 1.05–2.60]; mold: 26.3% vs 15.9% [OR: 1.89; 95% CI: 1.15–3.11]).
Table 4 shows the relationship of specific environmental exposures and ETS to measures of asthma morbidity and QoL. In general, exposures to potential allergens, with or without ETS, were unrelated to these measures. The exception is that cockroach exposure in households with ETS may increase children’s functional limitations and nighttime symptoms. We note, however, the large number of comparisons and relatively small number of significant findings.
These data demonstrate a high level of reported home exposure to ETS and common allergens among high-morbidity children with asthma recruited from an urban pediatric ED. However, there was no consistent relationship of any environmental exposure to multiple measures of asthma morbidity, including health care utilization, persistent asthma symptoms, or QoL. Only in the presence of ETS did cockroach exposure seem to adversely affect QoL.
ETS exposure in our cohort is higher than that found in other studies of high-morbidity asthmatics. Two reports from the National Cooperative Inner-City Asthma Study (NCICAS) found that between 48% and 59% of children in their cohorts lived in a home with a smoker.11,19 These rates are also higher than national data, showing that ∼43% of all US children aged 2 months to 11 years live in a home with at least 1 smoker.17 The rate of ETS exposure in our cohort is also much higher than the 25.7% of black adults in the District of Columbia who reported current smoking in 2003,18 no doubt at least partly reflecting the presence of multiple adults in the homes.
Reports of the rates of exposure to mold, cockroach allergen, and furry pets in our cohort are lower than those found in the NCICAS.19 In that national sample of inner-city children with moderate to severe asthma, 57.8% reported problems with cockroaches; 27.8% reported furry pets currently living in the home; and 45.4% of caregivers reported water, dampness, or water leaks. The NCICAS also reported lower household income than our cohort; thus, some of the difference in reported exposures may be related to socioeconomic status and the quality and type of housing. Perhaps more importantly, the NCICAS reported exposures in the previous 12 months, whereas we asked only about the previous month. Our data were consistent with others’ findings that cockroach exposure and sensitization are associated with lower socioeconomic status 20,21 and that cat and dust mite allergen exposure seems to be less common in high-poverty areas.21
An unexpected finding in secondary analysis revealed a significant relationship between exposure to ETS and exposure to cockroach allergen and mold. These associations persisted after controlling for household income and therefore are not exclusively socioeconomic effects. This finding merits additional prospective evaluation.
Although the documentation of exposure is important, a crucial issue is whether attempts to mitigate these exposures will improve outcomes in disadvantaged urban children living with asthma. Previous studies suggest that the issue is complex. For example, the use of allergen-barrier mattress pads and pillow covers to reduce exposure to dust mites has shown inconsistent results.22–26 In addition, reducing cockroach allergen in urban homes is challenging and in some studies has produced no apparent clinical benefit.22,27 However, a recent intervention aimed at reducing exposure to multiple indoor allergens and ETS has produced a significant and sustained decrease in asthma symptoms.28 This multifaceted intervention addressed those specific exposures to which each individual child was allergic. Although the study enrolled inner-city children with asthma, it did not recruit patients solely from the ED.
Within our population, the association of exposure to ETS and individual potential indoor allergens to health care utilization and morbidity was neither statistically nor clinically significant. However, exposure to both ETS and cockroach allergen was associated with 2 measures of diminished QoL. Other studies have looked at relationships among multiple exposures and between exposures and asthma outcomes. One study found that sensitization to dogs and cats increased in children with ETS and poor ventilation in the home.29 Another study suggests that allergens and viruses act together to exacerbate asthma.30 It is likely that chronic exposure to allergens and irritants among sensitive individuals increases bronchial reactivity, thus putting children at greater risk of exacerbation after acute exposure to trigger factors. Nonetheless, given the documented uncertainties regarding the efficacy of indoor home environmental modification, additional investigation will be necessary to clarify the role of exposure avoidance as a component of asthma interventions, particularly those taking place in the ED context.
Our study has several limitations. First, all of our data were obtained from caregiver report. In contrast, the NCICAS had independent evaluators assess home environments and sample for specific allergen content of vacuum-cleaner reservoirs. They found caregiver reports to be fairly accurate for ETS and furry pets but somewhat less reliable for cockroach and mold exposure.19 In addition, our health care utilization data depend entirely on caregiver reports. Second, we performed no allergy testing and therefore cannot describe the prevalence of allergen sensitivity in the cohort. However, recent studies have shown high levels of sensitivity to the exposures investigated here among high-morbidity asthmatics. For example, the NCICAS found that 93.9% of the children in that study had a positive skin test to ≥1 of the allergens tested, with the highest numbers of patients sensitive to cockroach (68.6%) and dust mite (61.8%) allergens.31 Thus, it is likely that a large proportion of the children in our cohort are indeed sensitive to the exposures discussed. Third, our analyses do not address the role of viral illnesses, which may account for the majority of asthma exacerbations in children.32,33 We did address the seasonal nature of asthma exacerbation by enrolling patients in all months of the year, including those months in which the viral load is lower. Finally, our cohort of patients represents a high-morbidity population of children who rely heavily on the ED for asthma care. Our results, therefore, are not generalizable to other populations who may have less-severe or better-controlled asthma and who may report different patterns of health care utilization.
We found high levels of exposure to ETS and potential allergens among a high-morbidity population of urban children with asthma. Although we were unable to directly evaluate the role of this chronic allergen and tobacco exposure on the patients’ airways, we noted little in the way of more distal clinical effects of these exposures. Specifically, with the exception of diminished asthma QoL among children exposed to both cockroaches and ETS, we found no reported evidence of an association between multiple exposures and increased morbidity or health care utilization. These data suggest that although the high levels of these exposures may contribute to the poor outcomes in this cohort, other factors may play a more important role in overall asthma morbidity and determining patterns of health care utilization.
Support for this study and publication of this article was provided by the Robert Wood Johnson Foundation. This study was supported by grant M01-RR020359 from the General Clinical Research Center Program of the National Center for Research Resources, National Institutes of Health, Department of Health and Human Services
Technical assistance was provided by the National Program Office (director, Gary Rachelefsky, MD, Allergy Research Foundation Inc; deputy director, Amy Stone, American Academy of Allergy, Asthma and Immunology; and research associate, Suzanne Kennedy, PhD, American Academy of Allergy, Asthma and Immunology). We acknowledge the statistical support of Robert J. McCarter, ScD, Cheng Shao, MPH, and Karen Schlumpf, MPH, and the database support of Bruce M. Sprague.
- Accepted December 6, 2005.
- Address correspondence to Stephen J. Teach, MD, MPH, Division of Emergency Medicine, Children’s National Medical Center, 111 Michigan Ave NW, Washington, DC 20010. E-mail:
Ms Hylan’s current address is Genzyme Corp, 500 Kendall St, Cambridge, MA 02142.
Dr Joseph’s current address is Department of Pediatrics, University of California, Davis, 2516 Stockton Blvd, Sacramento, CA 95817.
Financial Disclosure: Dr Teach serves on the speakers’ bureau for AstraZenca. The other authors have indicated they have no financial relationships relevant to this article to disclose.
- ↵Institute of Medicine, Committee on the Assessment of Asthma and Indoor Air. Clearing the Air: Asthma and Indoor Air Exposures. Washington, DC: National Academy Press; 2000
- ↵Weitzman M, Gortmaker S, Walker DK, Sobol A. Maternal smoking and childhood asthma. Pediatrics.1990;85 :505– 501
- ↵Eggleston PA, Buckley TJ, Breysse PN, Wills-Karp M, Kleeberger SR, Jaakkola JJK. The environment and asthma in U.S. inner cities. Environ Health Perspect.1999;107(suppl 2) :439– 450
- Nelson HS. The importance of allergens in the development of asthma and the persistence of symptoms. J Allergy Clin Immunol.2000;105(6 pt 2) :S628– S632
- ↵Tunnicliffe WS, Fletcher TJ, Hammond K, et al. Sensitivity and exposure to indoor allergens in adults with differing asthma severity. Eur Respir J.1999;13 :654– 659
- ↵National Heart, Lung, and Blood Institute; National Asthma Education and Prevention Program. Expert Panel Report 2: Guidelines for the Diagnosis and Management of Asthma. Bethesda, MD: National Institutes of Health; 1997. NIH publication No. 97-4051
- ↵Pediatric Asthma Committee. Pediatric Asthma: Promoting Best Practice Guide for Management of Asthma in Children. Milwaukee, WI: American Academy of Allergy, Asthma and Immunology; 1999
- Shields AE, Comstock C, Weiss KB. Variations in asthma care by race/ethnicity among children enrolled in a state Medicaid program. Pediatrics.2004;113 :496– 504
- ↵Centers for Disease Control and Prevention, National Center for Chronic Disease Prevention and Health Promotion. Prevalence data: District of Columbia—2003. Tobacco use. Available at: http://apps.nccd.cdc.gov/brfss/race.asp?cat=TU&yr=2003&qkey=4394&state=DC. Accessed March 17, 2005
- Gotzsche PC, Johansen HK, Burr ML, Hammarquist C. House dust mite control measures for asthma. Cochrane Database Syst Rev.2001;(3) :CD001187
- ↵Green RM, Custovic A, Sanderson G, Hunter J, Johnston SL, Woodcock A. Synergism between allergens and viruses and risk of hospital admission with asthma: case-control study. BMJ.2002;324 :763– 767
- ↵Johnston SL, Pattemore PK, Sanderson G, et al. Community study of role of viral infections in exacerbations of asthma in 9–11 year old children. BMJ.1995;310 :1225– 1229
- Copyright © 2006 by the American Academy of Pediatrics