Cost-effectiveness of outpatient versus inpatient non-invasive ventilation setup in obesity hypoventilation syndrome: the OPIP trial

Background Current guidelines recommend that patients with obesity hypoventilation syndrome (OHS) are electively admitted for inpatient initiation of home non-invasive ventilation (NIV). We hypothesised that outpatient NIV setup would be more cost-effective. Methods Patients with stable OHS referred to six participating European centres for home NIV setup were recruited to an open-labelled clinical trial. Patients were randomised via web-based system using stratification to inpatient setup, with standard fixed level NIV and titrated during an attended overnight respiratory study or outpatient setup using an autotitrating NIV device and a set protocol, including home oximetry. The primary outcome was cost-effectiveness at 3 months with daytime carbon dioxide (PaCO2) as a non-inferiority safety outcome; non-inferiority margin 0.5 kPa. Data were analysed on an intention-to-treat basis. Health-related quality of life (HRQL) was measured using EQ-5D-5L (5 level EQ-5D tool) and costs were converted using purchasing power parities to (GBP) pound. Results Between May 2015 and March 2018, 82 patients were randomised. Age 59 +/- 14 years, body mass index 47 +/- 10 kg/m(2) and PaCO2 6.8 +/- 0.6 kPa. Safety analysis demonstrated no difference in increment PaCO2 (difference -0.27 kPa, 95% CI -0.70 to 0.17 kPa). Efficacy analysis showed similar total per-patient costs (inpatient 2962 pound +/-580 pound, outpatient 3169 pound +/-525; pound difference 188.20 pound, 95% CI -61.61 pound to 438.01) pound and similar improvement in HRQL (EQ-5D-5L difference -0.006, 95% CI -0.05 to 0.04). There were no differences in secondary outcomes. Discussion There was no difference in medium-term cost-effectiveness, with similar clinical effectiveness, between outpatient and inpatient NIV setup. The home NIV setup strategy can be led by local resource demand and patient and clinician preference.