Rationale: The incidence of obesity hypoventilation syndrome (OHS) may be increasing in parallel with the present obesity epidemic. Despite extensive noninvasive ventilation (NIV) and continuous positive airway pressure (CPAP) use in patients with OHS, information regarding efficacy is limited.
Objectives: We performed a large, multicenter randomized controlled study to determine the comparative efficacy of NIV, CPAP, and lifestyle modification (control group) using daytime PaCO2 as the main outcome measure.
Methods: Sequentially screened patients with OHS with severe sleep apnea were randomized into the above-mentioned groups for a 2-month follow up. Arterial blood gas parameters, clinical symptoms, health-related quality-of-life assessments, polysomnography, spirometry, 6-minute-walk distance, dropouts, compliance, and side effects were evaluated. Statistical analysis was performed using intention-to-treat analysis, although adjustments for CPAP and NIV compliance were also analyzed.
Measurements and main results: In total, 351 patients were selected, and 221 were randomized. NIV yielded the greatest improvement in PaCO2 and bicarbonate, with significant differences relative to the control group but not relative to the CPAP group. In the CPAP group, PaCO2 improvement was significantly different than in the control group only after CPAP compliance adjustment. Additionally, clinical symptoms and polysomnographic parameters improved similarly with NIV and CPAP relative to the control. However, some health-related quality-of-life assessments, the spirometry, and 6-minute-walk distance results improved more with NIV than with CPAP. Dropouts were similar between groups, and compliance and secondary effects were similar between NIV and CPAP.
Conclusions: NIV and CPAP were more effective than lifestyle modification in improving clinical symptoms and polysomnographic parameters, although NIV yielded better respiratory functional improvements than did CPAP. Long-term studies must demonstrate whether this functional improvement has relevant implications. Clinical trial registered with www.clinicaltrials.gov (NCT01405976).
Keywords: noninvasive ventilation; obesity hypoventilation syndrome; sleep apnea.