Most people with mild to moderate obstructive sleep apnea (OSA with AHI of 5 to 30) have no bothersome daytime symptoms. In fact, less than a third (28%) experience daytime sleepiness that impairs their daily functioning (Epworth score > 10). No one had ever shown whether treatment with continuous positive airway pressure (CPAP) improves daytime symptoms and functioning in this very large group of people — millions in the U.S. alone.
Terri Weaver, Cristina Mancini, Samuel Kuna et al remedied that with the cleverly-named CATNAP trial. They gave 8 weeks of either CPAP or sham CPAP to 223 people meeting the above criteria, and crossed patients over to the opposite group to use them as their own controls.
The score on the Functional Outcomes of Sleep Questionnaire was the primary outcome measure (higher is better on this test). After 8 weeks, patients getting real CPAP had a mean improvement of 0.89 on their FOSQ scores, compared to -0.06 in the sham group. However, since a perfect score on the ten-question FOSQ is 40, it would appear to be a scant benefit.
CPAP is not consistently helpful for people with obstructive sleep apnea without daytime sleepiness, even if the OSA is severe, according to a 2001 randomized trial in Annals of Internal Medicine.
Who cares? Medicare and large insurance companies. Watching their payments to sleep physicians and CPAP companies skyrocket over the past 10 years, health care payers are starting to challenge the premise that an aggressive search for sleep apnea serves patients, or just the pocketbooks of those who treat them. With tens of millions of Americans believed to have undiagnosed OSA, mostly mild or moderate severity, the question of who will get tested and treated for obstructive sleep apnea — and who gets paid for it — is rapidly becoming more economic than academic.
Weaver TE et al. Continuous Positive Airway Pressure Treatment of Sleepy Patients with Milder Obstructive Sleep Apnea. Results of the CPAP Apnea Trial North American Program (CATNAP) Randomized Clinical Trial. AJRCCM 2012; 186: 677-683.
Read more: Sleep Medicine, 2012 PulmCCM Review