Childhood Asthma Risk Factors

Risk Factors

Asthma affects about 5 million American children between the ages of 5 and 14. Asthma has dramatically increased worldwide over the last few decades, in both developed and developing countries. From 1980 to 1994, asthma increased 160% in children younger than 4 years old and has risen dramatically in other countries as well. There is a wide variation in asthma incidence, however, ranging from over 50% among children in the Caroline Islands to virtually 0% in Papua New Guinea. The reasons for this wide variation are not yet known.

Gender

Among younger children, asthma develops twice as frequently in boys as in girls, but after puberty it may be more common in girls.

Socioeconomic Factors

Urban Life. Urban life is strongly associated with a higher risk. Although poverty plays a significant role, urban life, in fact, has been associated with a higher risk for asthma in any income group and among both children and adults. In some urban areas, as many as 25% of children have asthma or show signs of wheezing. In fact, it may be greatly underdiagnosed in city children. A 1999 Chicago study reported almost a third of children in inner-city kindergartens had asthma symptoms without a diagnosis of the disorder; 10% had actually been diagnosed with asthma, mainly because their symptoms were severe.

Ethnicity. Since 1980, asthma rates have risen the most dramatically among African American children, and they have significantly higher rates of asthma than Caucasian children. Hispanic children are also at higher risk. Both groups of minority children are more likely to have fatal asthma than Caucasian children.

Some studies indicate that the difference in risk exists simply because African Americans and other minority groups are more likely to live in urban areas. Poverty and lack of access to health care also play a role. However, Caucasian children who live in cities also face a high risk for asthma, and rural African-American children do not.

Urban life and socioeconomic factors, however, may not fully explain the ethnic disparity. For example, a 2000 study found that African-American children may have significantly higher levels of IgE than Caucasian children, suggesting a genetic susceptibility. (IgE are immune factors that play a critical role in asthma.)