- Moderate to severe OSA diagnosed on polysomnography, for which PAP therapy (continuous positive airway pressure or bi-level positive airway pressure) is prescribed by a physician. Overnight laboratory polysomnography, the gold standard for assessment of OSA115 and titration of PAP, will be performed and scored by a certified sleep technician, according to the American Academy of Sleep Medicine recommendations. Moderate to severe OSA will be defined as an obstructive apneahypopnea index (OAHI) of greater than or equal to 10 apneas or hypopneas per hour. Although no strict guidelines for defining severity of OSA in children exist, the definition for this study was derived by a consensus of pan-Canadian pediatric sleep medicine experts.