ETHNIC-DIFFERENCES IN THE PREVALENCE OF ASTHMA IN MIDDLE-CLASS CHILDREN

Background: Studies have shown a higher prevalence of asthma among boy s compared with girls and in blacks compared with whites, but it has b een difficult to separate socioeconomic from racial effects because th e blacks in the studied populations were more likely to have low socio economic status. Objective: To compare the prevalence of asthma in a s ocioeconomically homogeneous, middle class, multiethnic population of schoolchildren. Methods: Based on a telephone survey of all families o f third-graders in Southfield, Michigan, we ascertained the prevalence of physician-diagnosed asthma and probable undiagnosed asthma. One re ason Southfield was chosen for study was because the city comprises an integrated middle class population with only 4% blacks and 7% whites having incomes below federal poverty limits. Results: The lifetime pre valence of asthma was 9.5% (12% for blacks and 6% for whites) and high er in boys (14%) than girls (5%), a pattern that was reflected in peri od prevalence estimates. The lifetime prevalence of probable undiagnos ed asthma was greater in blacks (16.6%) than whites (10.8%), with litt le sex difference. Adjusting for sex and maternal education, the preva lence of physician-diagnosed asthma and probable asthma were associate d independently with black ethnicity. Conclusions: Our study is unique in the similarity of the black and white families' socioeconomic stat us and residence in the same middle class community. Since access to m edical care and macro-environmental conditions were similar across thi s study population, our results are consistent with the hypothesis tha t differences in biologic factors between blacks and whites and boys a nd girls play a role in asthma risk.