The Association Between Adherence to Positive Airway Pressure Therapy and Long-Term Outcomes in Patients With Obesity Hypoventilation Syndrome: A Prospective Observational Study

Study Objectives: To assess the role of different levels of adherence and long-term effects of positive airway pressure (PAP) therapy on gas exchange, sleepiness, quality of life, depressive symptoms, and all-cause mortality in patients with obesity hypoventilation syndrome (OHS). Methods: A total of 252 patients with newly diagnosed OHS were followed up for a minimum of 2 years after PAP initiation. PAP adherence (h/night) was monitored. Arterial blood gas samples were taken with patients being alert for more than 4 hours after morning awakening. Subjective daytime sleepiness (Epworth Sleepiness Scale [ESS]), quality of life (Short Form 36 [SF-36]) and patient's depressive symptoms (Beck Depression Inventory [BDI]) were assessed before and at the end of the follow-up period, along with all-cause mortality. Results: At the end of the follow-up period (median duration [25th-75th percentile], 30 [24-52] months), PaO2 increased from baseline (72.7 +/- 10.3 versus 63.2 +/- 10.6, P < .001) and both PaCO2 and HCO3- decreased (43.0 [39.2-45.0] versus 50.0 [46.7-55.4] and 27.5 +/- 3.2 versus 31.4 +/- 4.2, respectively, P < .001). In addition, PAP therapy significantly improved ESS (7 [4-9] versus 14 [11-16], P < .001), BDI (8.8 +/- 4.9 versus 15.5 +/- 7.3, P < .001) and SF-36 (82 [78-87] versus 74 [67-79], P < .001) scores. Over the follow-up period 11 patients died. Patients who used PAP for > 6 h/night had significant improvements (P < .05) in blood gases and SF-36 scores than less adherent patients. Conclusions: Increased hours of use and long-term therapy with PAP are effective in the treatment of patients with OHS. Clinicians should encourage adherence to PAP therapy in order to provide a significant improvement in clinical status and gas exchange in these patients. Commentary: A commenary on this article appears in this issue on page 1455.