Correlates of a Prescription for Bilevel Positive Airway Pressure for Treatment of Obstructive Sleep Apnea among Veterans

Introduction: The acceptance of portable home-based polysomnography together with auto-titrating CPAP has bypassed the need for a laboratory polysomnography. Since bilevel airway pressure (BPAP) is titrated in the sleep lab, patients diagnosed using portable home-based polysomnography may not have the opportunity to receive BPAP. It is unknown whether the patients who would have ordinarily received a BPAP would benefit from it. We determine correlates of receiving BPAP and of being switched from BPAP to CPAP. We examine whether patients with these correlates have better adherence to BPAP versus CPAP. Methods: Retrospective Cohort Study (Correlates at baseline) of 2,513 VA patients with a sleep study between January 2003 and October 2006 and receiving continuous or bilevel positive airway pressure (CPAP [N = 2,251]) or BPAP [N = 262]) by the end of 2007. PAP adherence up to 30 months was assessed. Results: Significant correlates of BPAP were older age (p < 0.001), higher BMI and CHF (p < 0.01), COPD (p < 0.001), higher blood CO2 (p < 0.05), higher AHI and OSA severity (p < 0.001), lower nadir SpO(2) (p < 0.001), and greater sleepiness (ESS) (p < 0.01). Patients on BPAP were more adherent to PAP therapy (p < 0.01), but the association largely disappeared following adjustment for BPAP correlates. There was preliminary evidence that these correlates predict long-term adherence to PAP therapy regardless of mode. Conclusions: We identified baseline factors that can help clinicians decide whether to prescribe an auto-BPAP as first-line therapy and that predict good long-term PAP adherence.