Long term effects of compliance with positive airway pressure (PAP) therapy in patients with obesity hypoventilation syndrome (OHS)

Abstract

Background: There is limited data concerning long-term effects of positive airway pressure (PAP) therapy on survival and functional status in patients with obesity hypoventilation syndrome (OHS).

Aims: To assess the role of different levels of compliance and long-term effects of PAP therapy on gas exchange, sleepiness, quality of life, depression and death rate in patients with OHS.

Methods: Two hundred fifty two OHS patients, newly diagnosed, who have been recommended PAP therapy, were followed up for a minimum of 2 years. Arterial blood samples were taken for gas level measurements with patients awake, for more than 4 h since wakening.The hours/day and percentage of days PAP was used were monitored. Epworth sleepiness scale (ESS), quality of life (Short Form 36-SF-36) and Beck Depression Inventory (BDI) were recorded together with the death rate before and at the end of the follow up period.

Results: At the end of thefollow-up period (mean duration, 50 months), PaO₂ had increased from baseline (p<0.001), and both PaCO₂ and HCO₃⁻had decreased (p<0.001). PAP therapy also significantly improved ESS (p<0.001), BDI (p<0.001) and SF-36(p<0.001) scores. During follow-up, 11 patients died (2 due to progressionof respiratory failure). Patients who used PAP therapy for > 6 hours/day had a considerably greater improvement in blood gases and questionnaires 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.