METHODS
The Childhood Adenotonsillectomy Trial (CHAT) was a single-blind, randomized, controlled trial at seven academic sleep centers (ClinicalTrials.gov number, NCT00560859). Methodologic details have been published previously [13]. Briefly, eligible children aged 5 to 9 years, with OSA syndrome (OSAS) without prolonged oxyhemoglobin desaturation considered suitable candidates for AT were enrolled. OSAS was defined as an obstructive apnea–hypopnea index (AHI) score of 2 or more events per hour or an obstructive apnea index (OAI) score of 1 or more events per hour. Children with an AHI score of more than 30 events per hour, an OAI score of more than 20 events per hour, arterial oxyhemoglobin saturation of less than 90% for 2% or more of the total sleep time were not eligible, owing to the severity of the polysomnographic findings. Exclusion criteria included recurrent tonsillitis, a z score based on the body-mass index (the weight in kilograms divided by the square of the height in meters) of 3 or more, and medication for attention deficit– hyperactivity disorder. Children were randomly assigned to two arms of treatment: early AT within 4 weeks after randomization or a strategy of watchful waiting with supportive care (WWSC).
The primary outcome of this post-hoc analysis was wheezing at 7-months of follow-up after AT. Wheezing was divided in two groups: “no wheezing” and “any wheezing”. The latter included rarely (less than once a week), sometimes (1 to 2 times per week), frequently (3 to 4 times per week) and always or almost always (5 to 7 times per week). “Any wheezing” was further divided according to the severity of wheezing in three groups: frequent wheezing (sometimes, frequent, and always), rarely wheezing, and no wheezing.