Suboptimal CPAP Adherence Still Results in Benefit for OSA, Daytime Sleepiness


New data has suggested that although adherence rates for CPAP for patients with OSA are lower than ideal, the benefits patients receive from its use can still be significant.

Dr Thomas Gaisl

Thomas Gaisl, MD, research clinician, Department of Sleep and Health, University of Zurich

Thomas Gaisl, MD

Even with suboptimal adherence to continuous positive airway pressure (CPAP), patients with moderate-to-severe obstructive sleep apnea (OSA) and daytime sleepiness can gain a substantial benefit, according to new study results. As adherence to CPAP is of the biggest challenges for physicians treating these conditions, these data are a welcome sign.

Whether a similar statement can be made for even lower adherence levels remains to be seen, according to the authors. Epworth-Sleepiness-Scale (ESS) scores for those who had suboptimal therapeutic use improved 2.4 points (95% CI, 0.6 to 4.2; P = .01) compared to standard therapeutic CPAP.

Patients were randomized through minimization to either suboptimal CPAP, which acted as the sham group (n = 26), or continued standard therapeutic CPAP, which acted as control (n = 26). Ultimately, the probability of superiority of the therapeutic CPAP over suboptimal CPAP was 90.4% for ESS, 90.1% for systolic, and 80.3% for diastolic blood pressure.

WATCH NOW: Reena Mehra, MD, MS: Adherence to CPAP in OSA

“In lieu of our findings and pre-existing literature, the widely used 4-hour-threshold for clinical benefit seems unjustified,” study author Thomas Gaisl, MD, research clinician, Department of Sleep and Health, University of Zurich, and colleagues wrote.

Gaisl et al detailed a trio of reasons to support that claim, noting that 1. There is much variability in sleep and sleepiness between individuals; 2. There are patients whose personal level of CPAP use is suboptimal; and 3. There is an inherent non-uniformity of sleep itself which may lend to a lower time-threshold to address excessive sleepiness, but not other aspects of OSA.

“Apart from the possibility of the overall time-thresholds for countering sleepiness and other sequelae being different, it is also conceivable that other aspects play their roles as well,” they detailed. “The thresholds of CPAP efficacy on different sequelae of OSA may not only be individual, but also composite — e.g. involving patterns of usage, adaptive pressures or varying air compositions.”

Although both study arms had a similar CPAP adherence in the 2 weeks prior to randomization (sham: 3.5 ±0.6 hours; standard: 3.1 ±0.8 hours), adherence dropped 1.4 hours in the sham group and rose 1.5 hours in the control group. Of those in the control group, 66% had an adherence above 4 hours at follow-up. The deviation in adherence was a significant 1.9 hours (95% CI, 0.4 to 3.6; P = .017), with ESS score improvements remaining a significant 2.0 points (95% CI, 0.5 to 3.2; P = .011) after adjustment.

Additionally, when conducting single-arm analysis for only sham CPAP, the ESS score was significantly increased by 2.1 points (95% CI, 0.5 to 3.2; P = .020).

“CPAP is currently the treatment of choice for sleepiness in patients with OSA, however, adherence is often thought to be suboptimal,” Gaisl and colleagues noted.

Reena Mehra, MD, MS, director, Sleep Disorders Research Program, and professor of medicine, Cleveland Clinic Lerner College of Medicine, who was not related to the study, told NeurologyLive in October 2019 that the real challenge is getting to the cause of a patients’ lack of tolerability to CPAP. She noted that there are a number of potential reasons, ranging from pressure intolerance and mask issues to nasal congestion and beyond.

“General adherence is thought to be 50% to 70%. Our estimates here at Cleveland Clinic are a bit higher, at 80%, maybe even 90%,” Mehra said. “The struggle is, really, to try to identify the root cause of the problem, in terms of why the patient is not able to tolerate the device.”


Gaisl T, Rejmer P, Thiel S, et al. Effects of suboptimal adherence of CPAP-therapy on symptoms of obstructive sleep apnea: a randomised, double-blind, controlled trial. Eur Resp J. 2019;55(1). doi: 10.1183/13993003.01526-2019.

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