Racial differences in physiologic parameters related to asthma among middle-class children.

BACKGROUND Asthma morbidity and mortality are higher in the United States for African-American (AA) children when compared to European-American (EA) children. STUDY OBJECTIVES To explore racial differences in physiologic factors associated with pediatric asthma severity. DESIGN Cross-sectional. METHODS We analyzed data from two groups of children in suburban Detroit, one of which contains non-urban, middle-class AA children, a group not usually included in childhood asthma studies. All children were 6 to 8 years of age. Clinical evaluations included medical history, physical examination, skin testing, spirometry, and methacholine challenge. RESULTS The study population (n = 569) was 14% African American, 51% of the participants were male, and the mean age was 6.8 +/- 0.4 years. Socioeconomic status (parental education) was similar overall by race, although some strata-specific differences were observed. The prevalence of physician-diagnosed asthma was 10% for both AA and EA groups. AA children were more reactive to methacholine than EA children (42% vs 22%, respectively; p = 0.001), and had significantly higher total IgE than EA children (geometric mean, 60. 6 vs 27.5 IU/mL; p = 0.001). Serum IgE was related to methacholine reactivity in EA children (p = 0.001), but not AA children (p = 0. 73). These differences remained after adjustment for gender, age, parental education, parental smoking, and maternal smoking during pregnancy. CONCLUSIONS Our data support previous reports of racial differences in lung volume, airway responsiveness, and serum IgE concentrations. We found a racial difference in the relationship between total serum IgE and airway responsiveness that is unreported elsewhere. Overall, our results suggest that AA children may be predisposed to asthma.