The only reason why CPAP has such abysmal failure rates, is because followup is an absolute joke. Patients are titrated in a sleep centre, typically for one night, and are then sent home with a machine, probably the shittiest mask the sleep centre had on hand, and a kick out the door. With some luck, patients have to come in once a year, usually to prove that their therapy is compliant with whatever harebrained schem…
Even my primary care doctor said he has abysmal compliance rates with apnea treatment because so many people decide that wearing any device every night is too much to ask.
I half suspect that apnea is being diagnosed so aggressively that people with even mild apnea are getting treatment. This would explain why patients are willingly giving up a treatment that is life changing for the better in patients who are suffering severe symptoms.