Asthma as a predictor of obstructive sleep apnea in urban African-American children.

BACKGROUND: Asthma is a known co-morbid factor in childhood obstructive sleep apnea (OSA); however, little is known about the effects that asthma might have on the severity of OSA. We hypothesize that children with concomitant asthma and OSA have more severe OSA.
METHODS: We conducted a prospective study of 50 children with OSA diagnosed by polysomnography referred for tonsillectomy and adenoidectomy (T&A). The presence of concomitant asthma was determined by ISAAC questionnaire and spirometry. Atopy to common allergens was determined by skin prick testing. Due to the relatively small sample size, we limited hypothesis testing to cross tabulations with Fisher's Exact Test and t testing. We also employed a parsimonious ordinary least squares (OLS) regression assuming a large effect size.
RESULTS: Subjects (n = 50) included 32 males and 41 African-Americans. Age at T&A was 9.3 +/- 3.4 years (mean +/- S.D). Thirty-two subjects reported a history of asthma during their lifetimes, but the ISAAC questionnaire detected only 30 subjects. Twenty-two subjects reported current asthma. Atopy was found in 27 subjects. Apnea-hypopnea index (AHI) was lower in the current asthma group than in the lifetime asthma group but did not reach statistical significance. However, AHI was significantly higher in subjects with poorly controlled asthma. Further, in a parsimonious OLS model controlling for sleep efficiency and age, a history of lifetime asthma increased the AHI by 8.8 (p < 0.05). DISCUSSION: In urban African-American children referred for T&A to treat OSA, a history of poorly controlled asthma is associated with more severe OSA.