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Final Report: Multi-component Intervention Study of Asthma in Children from Rural Communities
EPA Grant Number: R826711C002Subproject: this is subproject number 002 , established and managed by the Center Director under grant R826711
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
Center: University of Iowa Children's Environmental Airway Disease Center
Center Director: Hunninghake, Gary W.
Title: Multi-component Intervention Study of Asthma in Children from Rural Communities
Investigators: Chrischilles, Elizabeth , Hunninghake, Gary W. , Merchant, James A. , Schwartz, David
Institution: University of Iowa
EPA Project Officer: Fields, Nigel
Project Period: January 1, 1998 through January 1, 2002
Project Amount: Refer to main center abstract for funding details.
RFA: Centers for Children's Environmental Health and Disease Prevention Research (1998)
Research Category: Children's Health , Health Effects
Description:
Objective:Despite the availability of effective treatment for childhood asthma, reports of morbidity and mortality continue to increase in prevalence and in severity. It is increasingly recognized that environmental agents play a very important role in the development and progression of asthma; however, almost no information is available on distributions of environmental factors in rural households and the impact these factors have on childhood asthma. There is now convincing evidence that a community-based, multi-component intervention approach is the best route to prevent and control childhood asthma. The objective of this research project was to develop, implement, and test a community-based, multicomponent model for the prevention of asthma among rural children.
Summary/Accomplishments (Outputs/Outcomes):Prevalence of Rural Childhood Asthma
In the face of conflicting findings about the prevalence of asthma among farm and nonfarm children, we conducted a population-based mailed questionnaire screening of schoolchildren aged 6 to 14 years enrolled in 10 school districts in 2 noncontiguous rural Iowa counties during 2000/2002 (Chrischilles, et al., 2004). Conducted as part of the Rural Childhood Asthma Study (RCAS), the questionnaire included the International Study of Asthma and Allergies in Childhood core questionnaire, items from the Functional Severity Index, and items on doctor diagnosis, medication use, urgent care use, and farm/nonfarm residence. The response rate was 87 percent. Twelve month prevalence of wheeze among 3090 respondents was 19.1 percent and self-reported doctor diagnosis was reported by 13.4 percent. The estimated prevalence in rural Iowa is higher than rural Canadian and European populations and comparable to studies that used the ISAAC in Chicago, Minneapolis, and Seattle.
Doctor Diagnosis and Asthma Control in the RCAS
Only 178 (41.6%) of 428 schoolchildren with frequent symptoms reported a doctor diagnosis; 102 (67.5%) of 151 with severe symptoms reported a doctor diagnosis—underdiagnosis of asthma may be responsible.
We developed a scoring system from the screening questionnaire to be used as the first stage in a two stage screening process for identifying children who appear to have uncontrolled asthma. The scoring algorithm requires testing (positive predictive value) against a gold standard of physician-reviewed in-person clinic evaluation of asthma control. The scoring system should improve the portability of the intervention to other rural communities in the future.
Asthma Morbidity in the RCAS
During the RCAS, children were eligible to participate if they had ever been told they had asthma (“Has a doctor ever told you your child has asthma?”) or if they had “taken any medications for wheezing” in the past year. Among the 528 children eligible for enrollment in RCAS, 54 percent enrolled and 72.5 percent of these completed the home baseline data collection visit.
With the above eligibility criteria, we found during counselor interviews that 28 percent of eligible children had uncontrolled asthma symptoms as defined by: nocturnal awakening more than 2 times per month, quick-relief inhaler use more than 2 times per week, exercise limitation more than 2 times per week, equal to or more than 25 percent of days with bothersome asthma, if asthma ever had limited speech to only one to two words between breaths, missed 2 or more consecutive school days because of asthma, had any ER visits or hospitalizations, or had times during exacerbations when a quick-relief inhaler did not work well. To improve the efficiency of the RCAS management model, enhance its portability, and achieve a meaningful effect size, we recommend that future evaluation of this asthma management model include only children with uncontrolled asthma.
Change in Symptoms From Baseline to Followup
Significantly more intervention than control county children reported no bothersome asthma days and this difference was more marked and statistically significant at followup (Table 1). Although the measure is imprecise, it suggests an improvement in control of persistent symptoms. There were no differences between intervention and control children in number of school days missed in the last 2 months because of asthma, a measure indicative of exacerbation control. There are several sources of imprecision in our measures, many of which emanate from previously poorly understood characteristics of rural children with asthma. Based on these lessons we propose the following measurement strategies for future community-based intervention research:
- First, include only children with uncontrolled asthma symptoms because children who have no or few asthma symptoms create a ceiling effect, decreased subject variability, and poor reliability. This was a problem in RCAS where, of 192 children enrolled in waves 1 and 2, 33 percent were determined to have asthma that was in remission (i.e. one-third could not benefit from intervention) thereby reducing reliability.
- Second, instead of annual 14-day recalled symptom measures, measure mean symptom scores over repeated 2-week measurement periods preintervention and during followup to increase the precision of these symptom measures.
- Third, collect symptom data prospectively via asthma diary rather than via recall.
- Fourth, enroll all subjects during the winter cold season to maximize symptoms and control for interseason variability.
Table 1. RCAS Change in Percent of Days Bothered, Baseline to Followup, By Study Group. “Approximately what percent of the days in the past 12 months has {CHILD} been bothered by his/her asthma or wheezing?”
(Restricted to waves 1 and 2 with complete baseline and followup surveys, n=74)
Baseline |
Followup |
|||||
Bothered… |
Intervention |
Control |
p |
Intervention |
Control |
p |
more than 25% of days |
3.2% |
11.6 |
.09 |
3.3 |
11.7 |
.03 |
some but < 25% of days |
61.3 |
62.0 |
50.0 |
72.1 |
||
none of the days |
35.5 |
16.3 |
46.7 |
16.3 |
||
Evaluation of the RCAS Process
The RCAS intervention included three in-home asthma counselor visits, physician letters containing customized medical and environmental management recommendations, and case-based learning sessions with area primary care providers. We have described the asthma management problems among participating children, the medical and environmental recommendations made, and the physician and family responses to those recommendations (Chrischilles, et al., 2003). Counselor recommendations were implemented from 50 to 66 percent of the time. The study documented that the RCAS model can change asthma management behavior when implemented by the developers in one study county for children who already have a diagnosis of asthma. Preliminary analyses of the first two waves of data indicated improvements in medical management behavior in the intervention county relative to controls (e.g., the percent of children with written quick relief plans from their physicians increased from 17.2% in the intervention county to 37.5%). Among controls, the percent decreased slightly from 19.4 percent to 13 percent. The difference between counties was significant on univariate analysis (p = 0.03). At the end of three visits, the counselor often felt more time was needed for well-formed behavior change. Future research should compare the effectiveness of eight visits with four visits through use of a lagged intervention control group. This also would provide an important motive for study retention among subjects randomized to the control group.
Most Significant Achievements
The study documented that the RCAS model can change asthma management behavior when implemented by the developers in one study county for children who already have a diagnosis of asthma. There is some evidence that this resulted in improved symptoms control, however measurement precision should be increased in future studies.
From the two-county RCAS, we have determined that a disease management model for a rural state must have a regional component. Funding agencies and policymakers must rethink the meaning of a rural “community”—continued conceptualization of the rural community using traditional urbanized mental models is detrimental to community-based participatory research in rural environments. Though uncontrolled asthma is prevalent and rivals that in large U.S. cities, the absolute number of children with uncontrolled symptoms is too small in most rural school districts to justify hiring an asthma counselor and the volume would be too low to sustain quality. During the first two enrollment years of the RCAS, 22 of 78 intervention group children (28.2%) had uncontrolled asthma symptoms. These were distributed across four small school districts (n=13, n=4, n=3, and n=2 from each district). Further emphasizing the implications of population density for community definition is the fact that half of the 36 towns served by the 10 RCAS school districts had a population less than 100.
Future research should use a randomized controlled trial design to test a regionalized delivery of the RCAS asthma management model: a multi-component intervention model for managing childhood asthma in a rural state.
Journal Articles on this Report: 1 Displayed | Download in RIS Format
| Other subproject views: | All 11 publications | 10 publications in selected types | All 10 journal articles |
| Other center views: | All 33 publications | 32 publications in selected types | All 32 journal articles |
| Type | Citation | ||
|---|---|---|---|
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Chrischilles E, Ahrens R, Kuehl A, Kelly K, Thorne P, Burmeister L, Merchant J. Asthma prevalence and morbidity among rural Iowa schoolchildren. Journal of Allergy and Clinical Immunology 2004;113(1):66-71 and erratum in Journal of Allergy and Clinical Immunology 113(3):391. |
R826711 (Final) R826711C002 (Final) |
not available |
children’s health, asthma, airway disease, airway inflammation, allergen, allergic airway, assessment of exposure, asthma, biological response, childhood respiratory disease, community-based intervention, disease, dust, dust mites, environmentally caused disease, exposure, grain dust, harmful environmental agents, health effects, human exposure, inhalation, rural communities, sensitive populations,
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Scientific Discipline, Health, RFA, Susceptibility/Sensitive Population/Genetic Susceptibility, Biology, Risk Assessments, genetic susceptability, Health Risk Assessment, Children's Health, Atmospheric Sciences, Environmental Chemistry, Allergens/Asthma, environmentally caused disease, allergen, health effects, inhalation, dust , dust mite, rural communities, assessment of exposure, childhood respiratory disease, dust mites, allergic airway, harmful environmental agents, toxics, agricultural community, community-based intervention, sensitive populations, biological response, grain dust, airway disease, children, disease, exposure, children's vulnerablity, asthma, human exposure, Human Health Risk Assessment
Progress and Final Reports:
2000 Progress Report
Original Abstract
Main Center Abstract and Reports:
R826711 University of Iowa Children's Environmental Airway Disease Center
Subprojects under this Center:
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
R826711C001 Mechanisms that Initiate, Promote, and Resolve Grain Dust/LPS Induced Inflammation
R826711C002 Multi-component Intervention Study of Asthma in Children from Rural Communities
R826711C003 Role of RSV Infection and Endotoxin in Airway Inflammation
R826711C004 A Model to Study the Development of Persistent Environmental Airway Disease