This CPB is revised to state that a bilevel positive airway device with a backup rate feature is considered experimental and investigational for obstructive sleep apnea. This CPB is revised to state that custom-fabricated oral appliances are considered medically necessary for obstructive sleep apnea in persons that meet criteria for CPAP, but who are intolerant to positive airway pressure devices. This CPB is revised to state that a custom fabricated oral appliance is considered medically necessary only if there is an anatomical abnormality of the mouth, jaw, or throat that cannot be accommodated by a prefabricated appliance. These policy revisions are supported by Medicare Durable Medical Equipment Medicare Administrative Carrier (DME MAC) policy.