Evaluating the factors that relate to asthma severity in adolescents

Over the past 5 years, we have been engaged in a cross-sectional evaluation of risk factors for higher asthma severity in adolescents aged 13-18. All recruitment takes place through public and private schools. The sample from which our current findings are derived includes 151 adolescents covering a wide spectrum of asthma severity and socioeconomic status (SES) and representing both African American and Caucasians. An asthma severity instrument has been developed and validated for the purpose of this study. This yields an asthma severity score which is a continuous variable. Female gender and the number of positive skin tests are the best independent correlates to the asthma severity score. Among the 18 aeroallergens used in the study, the American cockroach Periplaneta americana is the only one that relates to the asthma severity score in a stepwise regression model. The two other cockroaches, German and oriental, as well as the dust mites Dermatophagoides farinae and Dermatophagoides pteronyssinus, correlate with the asthma severity only in simple regression analysis. The relationship between asthma severity and cockroach sensitivity is strongest within the lowest-income per family member quartile. This is consistent with the additional observations that (1) significantly higher rates of sensitization for cockroaches are observed in the lowest-income quartile subjects and (2) higher levels of the cockroach allergen Bla g 1 are found in their homes. Preliminary analysis suggests that ethnic background may interact with environmental exposure in that, within the lowest-income quartile, Caucasians have lower sensitization rates to cockroaches and other allergens compared to African Americans. Within the Caucasian population, income does not appear to influence sensitization rates. The treatment that adolescents with asthma receive for their respiratory disease is characterized by an overall low rate of prescribed inhaled corticosteroids (37% in the moderately severe and severe groups). This inadequacy in treatment is accentuated by SES: 28% of adolescents in the highest and 6% in the lowest-income quartile are prescribed these medications. Our findings are consistent with the hypothesis that the higher asthma morbidity and mortality observed in the African American population is related to higher exposure and sensitization to allergens such as those from cockroaches that are more prevalent in lower SES environments. It is possible that genetic factors contribute to the higher degree of sensitization. In addition, individuals of low SES are subjected to inadequate medical management of their asthma.