Flexible pressure delivery modification of continuous positive airway pressure for obstructive sleep apnea does not improve compliance with therapy: systematic review and meta-analysis

Background: Continuous positive airway pressure (CPAP) is the first-line therapy for obstructive sleep apnea (OSA), but patient compliance is a major barrier to long-term effectiveness. Flexible pressure delivery of PAP reduces pressure during early exhalation with the aim of improving comfort and, therefore, compliance, leading to subsequent symptoms improvement. Methods: We undertook a systematic literature search of PubMed (January 1, 2000, to July 11, 2010) to identify all randomized trials comparing flexible and standard CPAP in adult patients with OSA with at least 1-week follow-up. Either we or the original trial investigators extracted means, SEs, and sample sizes for all relevant outcome measures. We then performed meta-analyses quantifying improvements in objective compliance and symptoms as measured by the Epworth Sleepiness Scale (ESS), the Maintenance of Wakefulness Test (MWT), and the Psychomotor Vigilance Task (PVT). Results: We found 10 relevant trials (599 patients). Meta-analysis of the seven trials where we could extract compliance data (514 patients) indicated that flexible pressure did not improve compliance compared with CPAP in either the parallel (0.16 h; 95% CI, -0.09-0.42; P = .21) or the crossover trials (0.20 h; 95% CI, -0.26-0.66; P = .39). Flexible pressure caused no improvement over CPAP in any secondary outcome (ESS, MWT, PVT, and residual OSA, all P > .05). Conclusions: Flexible pressure modification neither significantly improves compliance with CPAP in patients with OSA nor significantly improves patient outcomes beyond the effects of CPAP. Unfortunately, we were unable to locate compliance data in the correct format for three out of the 10 suitable trials.