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What is Asthma?
Asthma is a disorder that generally results in inflammation of the airways in the throat and in the lungs and can cause episodes of wheezing, breathlessness, chest tightness, and couching particularly at night or in the early morning. This is usually associated with some restriction of airflow in and out of the lungs. The condition of asthma often increases sensitivity to irritants. Asthma has variations, and not all physicians agree on a single definition.
There is no laboratory test that can confirm asthma, and there is no clear line that separates children who have frequent wheezing and respiratory infections from children who have asthma. Tests of lung function are the best means to confirm asthma. (These involve measuring how much air a child can blow into a tube in a defined period of time.)
Asthma also varies considerably in its severity. Some children have infrequent or mild attacks, while others have frequent attacks that may be life threatening.
Why do kids get asthma in the first place?
No one knows for sure what causes asthma to develop in children (or adults.) Both genetic and environmental factors are thought to be relevant.
Genetics are thought to play some role, as children who have relatives with asthma are more likely to have asthma as well. However, asthma has increased dramatically in the last 20 years, and genetic change does not occur this rapidly, so genetics is not considered by most researchers to be the primary cause of the onset of asthma. The Institute of Medicine recently estimated that genetic factors represent 30 to 80% of asthma risk (1) and that the remainder is due to environmental factors. Many other possible factors have been suggested, and theories differ widely.
Environmental factors including exposure to environmental tobacco smoke, exposure to biological agents, lack of exposure to biological agents, exposure to toxic substances, or decrease in exercise have been suggested as possible causes of the development of asthma. No consensus has emerged as to which, if any, of these factors cause the disease.
Children are usually first diagnosed with asthma after they have had respiratory symptoms over a period of time. Asthma attacks are often called "exacerbation" of asthma. Diagnosis of asthma by a physician will usually occur at some time after the disease has developed in the child, and it is difficult or impossible to determine when the disease first occurred.
What triggers asthma attacks?
More is known about what triggers asthma attacks, partly because this is easier to study than what causes the development of the disease in the first place. Agents that are thought to cause asthma attacks include outdoor factors such as air pollutants, pollens, and fungi and indoor factors such as molds, dust mites, environmental (second hand) tobacco smoke, animal dander, fungi, cooking byproducts, and chemicals.
What is the cost of asthma in children?
A variety of estimates of the cost of asthma have been made. They vary, in part because they count different things. In the early 1990's, two studies estimated that costs of asthma in the US ranged from $5.8 billion to $6.2 billion (2, 3). Health care costs for children with asthma in 1987 were estimated to be 2.8 times as high as for children without asthma (4).
1. Institute of Medicine. Clearing the Air: Asthma and Indoor Air Exposures. Washington, DC: National Academy Press, 2000.
2. Weiss KB, Gergen PJ, Hodgson TA. An economic evaluation of asthma in the United States. New England Journal of Medicine 326:862-6(1992).
3. Smith DH, Malone DC, Lawson KA, Okamoto LJ, Battista C, Saunders WB. A national estimate of the economic costs of asthma. American Journal of Respiratory and Critical Care Medicine 156:787-93(1997).
4. Lozano P, Sullivan SD, Smith DH, Weiss KB. The economic burden of asthma in US children: estimates from the National Medical Expenditure Survey. Journal of Allergy and Clinical Immunology 104:957-63(1999).
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Last updated July 5, 2001 | Send questions or comments to firstname.lastname@example.org | © Copyright 2001 Amy D. Kyle