Narayanan A, et al. - In this retrospective case-control analysis including 367 children (aged 9 to 17 years) who had full-night polysomnography (PSG), the relationship between asthma, obesity, and severe obstructive sleep apnea [defined by intermittent episodes of airway obstruction resulting in periods of oxygen desaturation and hypercapnia during sleep] (sOSA) were analyzed. The authors discovered that asthma prevalence was 188 out of 367, obesity was 197 out of 367 (54%), and sOSA was 109 out of 367. The presence of asthma reduced the probability of sOSA in obese patients by an average of 14% and in nonobese patients by 9%. Even after controlling for age, gender, race, income, and tonsillar hypertrophy, these associations held. Among a large cohort of older children referred for PSG, asthma presence decreased while obesity increased the likelihood of sOSA. These associations have been additive.