Asthma : Minorities, What Causes Asthma?

by Food and Drug Administration (FDA)

(Page 4 of 4)

Asthma Death Rates Higher for Minorities

Black Americans have only a slightly higher prevalence rate of asthma than whites (8.5 percent versus 7.1 percent), but blacks are three times more likely to die or be hospitalized because of the disease. According to the Centers for Disease Control and Prevention, while asthma mortality rates have gone down overall since 1995, racial disparities remain.

Floyd Malveaux, M.D., dean of Howard University's College of Medicine in Washington, D.C., says the reasons are complex. "We know that this is one of many diseases in which minorities and underserved populations are disproportionately affected," he says. "A lot of the disparities are related to poverty."

Malveaux says lack of access to care plays a large role. "It's not just about having health insurance," he says, "but also about whether there is access to transportation and knowing how to use the health care system. There may be no access to asthma specialists, perhaps because of limitations in managed care. So then what you have is a reactive situation and a lot of emergency room visits versus a proactive situation that focuses on prevention."

He also points out that when you're living in poverty you can't control the environment like you may want to. "I think of an area in Detroit where big diesel trucks come across from Canada," he says. "You can see the line of trucks emitting diesel fuel in a poor neighborhood, and the people who live there can't control that."

Other factors may be the challenge of paying for asthma medications and exposure to smoking and cockroaches. Research supported by the National Institute of Allergy and Infectious Diseases has found that children in inner-city areas who were both allergic to cockroaches and heavily exposed to them had higher rates of hospitalization for asthma, missed school more often, and suffered more sleep loss.

Hispanics also have higher death rates from asthma compared with whites, with Puerto Ricans experiencing the highest burden.

What Causes Asthma?

Inflammation (swelling) of the airways is the underlying cause of asthma, and there are two main reasons that people develop the disease, says Fernando Martinez, M.D., director of the Arizona Respiratory Center at the University of Arizona College of Medicine in Tucson. "Some people develop asthma because they react to viral infections like the common cold. Another group is genetically predisposed to it, and for them, asthma is associated with the way the lungs grow and the way the immune system develops." It is in this second group that asthma tends to be persistent, and there is often a family history of asthma and allergies. "Over the next decade," Martinez says, "determining which genes are involved will help scientists prevent and treat the disease."

William Busse, M.D., professor of medicine in allergy and immunology at the University of Wisconsin Medical School, says the causes of the increasing asthma rates are not fully understood. He says that the prevalence of asthma is higher in developed countries, such as the United States, Europe, and New Zealand, and is lower in less developed areas, such as China and Africa. This suggests a possible role of environmental or lifestyle factors that may affect the type and magnitude of exposure to environmental allergens and immune response to that exposure. Researchers are exploring possible factors such as diet, frequent use of antibiotics, and fewer and less severe infections in early life. Busse says studies have shown that children who are enrolled in day care before 6 months of age have more frequent infections in early life, but significantly less asthma after age 6.

Asthma also occurs more in urban environments than in farming ones. The Hygiene Hypothesis, first proposed in 1989, remains under debate and requires further study, according to Busse. This hypothesis states that environments that are too clean may actually make immune function more likely to develop allergic responses. In a study published in the Sept. 19, 2002, issue of The New England Journal of Medicine, researchers studied 812 children ages 6 to 13 living in rural areas of Germany, Austria, and Switzerland, and found that children in farming households experienced a decreased risk of hay fever and asthma.

Safety Study on Serevent

In January 2003, the FDA announced that an interim analysis of a large safety study of the asthma drug Serevent (salmeterol) Inhalation Aerosol suggests that the drug may be associated with an increased risk of life-threatening asthma episodes or asthma-related deaths. Further analyses of the data suggest that the risk might be greater in blacks. Also, people not taking inhaled corticosteroids when they entered the study appeared to have greater risk for serious outcomes than those who were taking inhaled corticosteroids.

Serevent Inhalation Aerosol belongs to the class of asthma medications known as beta-2 receptor agonists, commonly called beta-agonists. The FDA approved the drug in 1994 to treat asthma, and approval was later extended for treatment of chronic obstructive pulmonary disease (COPD).

The safety study began in 1996 after the FDA received reports of several asthma deaths associated with the use of Serevent Inhalation Aerosol, and after studies raised concern about the regular use of short-acting and long-acting beta-agonists.

Because people with asthma can sometimes suffer sudden, serious life-threatening episodes of bronchospasm, the deaths and serious adverse events reported for Serevent could neither be attributed to use of the product, nor could Serevent be excluded as a cause. The drug's manufacturer, GlaxoSmithKline of Research Triangle Park, N.C., stopped the study, mostly due to difficulties in enrollment and the likelihood the study would not give a clear result.

The FDA is considering what steps are warranted to address this important new risk information. The FDA has emphasized that, based on available data, the benefits of Serevent for people with asthma continue to outweigh the risks and that serious problems reported in the trial were rare. The FDA has strongly advised that people who take Serevent should not stop taking it, or any other asthma drug, without first talking with their physicians.

About the Author

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