Identification of population subgroups of children and adolescents with high asthma prevalence - Findings from the Third National Health and Nutrition Examination Survey

Objectives: To provide national estimates of asthma prevalence in African-American, Mexican American and white (non-Latino) children and adolescents using several common definitions; to evaluate familial, sociodemographic, and environmental risk factors that are independently associated with current asthma in children and to identify subgroups at particular risk for current asthma using 2 complementary data analytic approaches. Design: Cross-sectional study, using the Third National Health and Nutrition Examination Survey, 1988-1994. Setting: Eighty-nine mobile examination centers in the United States. Participants: Twelve thousand three hundred eighty-eight African American, Mexican American, and white (non-Latino) children and adolescents, aged 2 months through 16 years, selected from a systematic random, population-based, nationally representative sample. Main Outcome Measure: Current asthma, defined by caregivers who reported that their child currently had doctor-diagnosed asthma. Results: The overall prevalence of current asthma was 6.7% (95% confidence interval [CI], 5.6-7.8). Odds ratios for current asthma from the multiple regression analysis were 4.00 (95% CI, 2.90-5.52) for children with a parental history of asthma or hay fever, 1.94 (95% CI, 1.09-3.46) for children with body mass index (calculated as weight in kilograms divided by the square of height in meters) greater than or equal to the 85th percentile, and 1.64 (95% CI, 1.20-2.26) for children of African American ethnicity. African American and Mexican American children showed a consistent prevalence of current asthma across age while white children showed an increase in prevalence with age. The 2 highest-risk subgroups identified by the signal detection analysis were composed of children with a parental history of asthma or hay fever who were 10 years or older with a body mass index greater than or equal to the 85th percentile (31.0% current asthma), and children with a parental history who were 10 years or younger and of African American ethnicity (15.6% current asthma). Conclusions: The findings from this analysis show a strong independent association between obesity and current asthma in children and adolescents, and confirm previous reports of a parental history of asthma or hay fever and African American ethnicity as additional important risk factors.