CPAP is the first-line medical treatment for OSA in adults. It has been shown to reduce or normalize the apnea-hypopnea index (AHI), oxygen desaturations, and arousals from sleep, which are characteristics of OSA. However, the practical benefits of CPAP are limited by patients’ use of the treatment. Over the past 20 years, a large body of evidence suggests that average CPAP use is 4.7 hours/night and that approximately 50% of adults prescribed CPAP are not adherent to therapy (Sawyer et al. Sleep Med Rev. 2011;15[16]:343). These excessively high rates of nonadherence contribute to discordance between the high efficacy of CPAP and its far more modest effectiveness in clinical practice.
Health-care providers and researchers historically depended upon self-reported CPAP use as the measure of treatment adherence. Unfortunately, this metric is now recognized as inadequate, as it typically overestimates actual use.