Rationale: Obesity hypoventilation syndrome (OHS) is an undesirable consequence of obesity. Treatment consists of weight loss and positive airway pressure (PAP) therapy. However, the preferred mode of PAP is uncertain.Objectives: To perform a systematic review to determine whether PAP therapy should be initiated as noninvasive ventilation (NIV) or continuous PAP (CPAP) in ambulatory patients with OHS.Methods: This systematic review informed an international, multidisciplinary panel of experts who had converged to develop a clinical practice guideline on OHS for the American Thoracic Society. MEDLINE, the Cochrane Library, and Embase were searched from January 1946 to March 2019 for studies that compared initial treatment with NIV to CPAP in OHS. The Grading of Recommendations, Assessment, Development, and Evaluation approach was used to appraise the quality of evidence.Results: The search identified 2,994 potentially relevant articles, the full text of 21 articles was reviewed, and five articles were selected. The five articles included three randomized trials (one reported as two articles) and an observational study. The sample size ranged from 36 to 225 subjects. The evidence showed no differences in mortality, cardiovascular events, and healthcare resource use between patients with OHS treated with NIV or CPAP. Both PAP modalities were similarly effective in improving gas exchange, the need for supplemental oxygen, daytime sleepiness, sleep quality, quality of life, dyspnea, and sleep-disordered breathing. There was also no significant difference in adherence to NIV or CPAP therapy. Certainty in the estimated effects was low or very low for some outcomes. Therefore, the conditional recommendation was based on very low-quality evidence.Conclusions: The panel made a conditional (i.e., weak) recommendation that CPAP rather than NIV be offered as the first-line treatment to stable ambulatory patients with OHS and coexistent severe obstructive sleep apnea (OSA). The effectiveness of CPAP is similar to that of NIV, but NIV is more costly and requires more resources than CPAP. Given that approximately 70% of patients with OHS have coexistent severe OSA, this recommendation applies to the great majority of patients with stable OHS, but it should not be extrapolated to patients with OHS without severe OSA. Patients of advanced age, with poor lung function, or with greater or recent acute ventilatory failure may not respond adequately to CPAP.
Keywords: Pickwickian; bilevel PAP; hypercapnia; hypercarbia; pressure support.