Asthma and Minority Populations

Asthma affects nearly 15 million Americans, more than 5 percent of the U.S. population. In 1991, asthma claimed approximately 5,000 lives. After a decade of steady decline in the 1970s, the prevalence of asthma, hospitalizations for asthma, and mortality due to asthma each increased during the 1980s.

Asthma is a growing concern in this country, particularly in inner-city African-American and Latino populations.

In 1993, among children and young adults, African Americans were three to four times more likely than whites to be hospitalized for asthma, and were four to six times more likely to die from asthma. Poverty, substandard housing that results in increased exposure to certain indoor allergens, lack of education, inadequate access to health care, and the failure to take appropriate medications may all contribute to the risk of having a severe asthma attack or, more tragically, of dying from asthma.

In 1991, to address the concerns about asthma in the inner city, the National Institute of Allergy and Infectious Diseases (NIAID), a component of the National Institutes of Health, launched the first National Cooperative Inner-City Asthma Study. The primary aim of the study was to identify factors responsible for the rise in asthma among inner-city children and to test new strategies for asthma intervention.

Phase I of the first National Cooperative Inner-City Asthma Study (1991-1994) was designed to identify factors associated with severity of asthma in children ages 4-11. The second phase, completed in February 1996, studied the effectiveness of a comprehensive program to develop improved knowledge about asthma, to promote better asthma self-management skills, and to eliminate or decrease exposure to environmental factors associated with increased morbidity from asthma.

Phase I enrolled 1,528 children and their families. The study population was 73 percent African American, 20 percent Latino, and 7 percent Caucasian. Asthma risk factors found to be present in these urban families included: high levels of indoor allergens, especially cockroach allergen; high levels of tobacco smoking among family members and caretakers; and high indoor levels of nitrogen dioxide, a respiratory irritant produced by inadequately vented stoves and heating appliances. Many patients also reported difficulties in obtaining follow-up care for their asthma. Low socioeconomic status and African-American race were independent risk factors for allergic sensitization to cockroach allergens. Thus, new approaches to reduce exposure to cockroach allergens may be very useful in controlling asthma.

More than 1,000 children were enrolled in Phase II of the study. Several sites used a Spanish-language program in addition to the standard English- language program. These sites employed bilingual counselors and modified the intervention to account for cultural issues unique to a Latino population. A key component of the Phase II intervention was the use of an "asthma care counselor" whose primary role was to teach and monitor acquisition of asthma self-management skills. While the results are still preliminary, children in the intervention limb of the study had striking reductions in major symptoms, in school absenteeism, in hospitalizations, and in emergency room visits for asthma.

Based on the success of the first National Cooperative Inner-City Asthma Study, NIAID and the National Institute of Environmental Health Sciences (NIEHS) recently initiated a second cooperative multicenter study. A major objective is to extend and disseminate the findings of the first National Cooperative Inner-City Asthma Study. This continuation includes new educational programs for patients and physicians, and focuses on community-specific interventions and on the relationship between asthma morbidity and the environment.

In collaboration with the National Heart, Lung, and Blood Institute (NHLBI), NIAID is funding a cooperative study at four centers to explore the genetic basis of asthma. This study is enrolling asthmatic patients and their families — many of whom are from ethnic minorities — in order to identify genes for asthma and for responsiveness to allergens. This study has identified several candidate genes for asthma, some of which may be more common in African-American populations. In other studies, investigators supported by NIAID have identified a genetic change in interleukin-4 (IL-4), an immune-signaling molecule involved in asthma and allergic responses, that correlates with asthma severity. This change appears to be several-fold more common among African Americans than among whites. Studies of such genes should facilitate development of new and more potent and selective therapies, and may help to identify patient populations who might respond best to a particular drug.

Reprinted with permission from the National Institute of Allergy and Infectious Diseases

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