(American Thoracic Society) - The disturbingly high prevalence of asthma among black children in the United States is not attributable to race, but to urban living, according to a new research study published in the September issue of the American Journal of Respiratory and Critical Care Medicine.

C. Andrew Aligne, M.D., of Strong Children’s Research Center, Rochester General Hospital, Rochester, New York, along with three associates, examined a nationally representative sample of 17,110 children from birth to age 17 for parent-reported current asthma. Of this group, 4.2 percent (747 children) had asthma during the preceding 12 months. In unadjusted analysis, black children were found to have a significantly higher prevalence of asthma than white children. However, after controlling for multiple variables, black race was no longer considered a significant correlate for the disease.

The researchers examined their database for variables such as race, poverty status, and urban residence. “We found that when children are categorized by urban status,” said Dr. Aligne, “all urban children had a heightened risk of asthma regardless of race or family income.”

The investigators point out that asthma appears to be a disease of modern civilization with early-life environmental exposures leading to increased hypersensitivity and finally to bronchial hyperreactivity and airway inflammation.

“Asthma does not seem to be a racially linked disease,” noted Dr. Aligne. “Indeed, black populations living in Africa have very low prevalence, and the asthma that does occur is associated with environmental factors related to urbanization.”

According to the paper, the International Study of Asthma and Allergies in Children, an investigation of 13- to 14-year-old children, revealed a striking difference in the prevalence of asthma worldwide, with the greatest prevalence about 20 times higher than the lowest. The United States is one of the high prevalence countries. The authors say the worldwide variation in rates suggest that environmental factors are critical to the development of the disease.