Cost Effectiveness of Outpatient Set-up of Automated NIV in Obese Patients With Chronic Respiratory Failure

Obesity is an escalating issue, with an accompanying increase in referrals of patients with obesity-related respiratory failure. Currently, these patients are electively admitted to hospital for initiation of non-invasive ventilation (NIV), but it is unknown whether outpatient initiation is as effective as inpatient set-up. The investigators hypothesise that outpatient set up using an auto-titrating NIV device will be more cost effective than nurse-led inpatient titration and set-up.

The investigators will undertake a multi-national, multi-centre randomised controlled trial.

Subjects will be randomised to receiving usual inpatient set-up, which will include nurse-led initiation of NIV or outpatient set-up with an automated NIV device. Subjects will be stratified according to trial site, gender and previous use of NIV or continuous positive airway pressure. Assuming 10% drop out rate, a total sample of 82 patients will be required. Cost effectiveness will be evaluated using standard treatment costs and health service utilisation and using health related quality of life measures (SRI and EQ5D). Change in the severe respiratory insufficiency (SRI) questionnaire will be based on analysis of covariance (ANCOVA) adjusting for the baseline measurements between the two arms of patients.

There is an increase of patients with hypercapnic respiratory failure as a consequence of obesity. The current treatment options for patients with obesity related respiratory failure is non-invasive ventilation (NIV). This has shown to reduce partial pressure of arterial carbon dioxide (PaCO2) and improves symptoms such as dyspnea (breathlessness)and enhances quality of life. NIV has also shown to increase physical activity (using actigraphy)and there can be associated weight reduction after three months of initiation.

Currently, the length of an inpatient stay for NIV set up is between 4.5 and 6 days. As yet it is unknown whether or not a patient can be set up onto NIV as effectively on an outpatient basis using an AE-AVAPS (Automatic Expiratory Positive Airway Pressure - Average Volume Assured Pressure Support) algorithm compared to the usual practice of inpatient titration by specialist respiratory nurses. Furthermore, the cost effectiveness of outpatient initiation vs inpatient initiation is unknown in this group of patients.

This will be the first trial to assess the cost effectiveness of such a set up.

Eligibility Criteria:
Inclusion Criteria:

* Obese patients with chronic respiratory failure
* Age \> 18 years
* Chronic hypercapnia (daytime PaCO2 \> 6.0kPa)
* Evidence of sleep disordered breathing on overnight oximetry study (4% oxygen desaturation index \>10events per hour and/or \>30% of the total analysis time with an SpO2 \< 90%)
* Patients with a recent acute episode requiring non-invasive ventilation will need a minimum of 2 weeks stability prior to enrolment into the trial (no NIV requirement for 2 weeks and pH (Inverse logarithm of hydrogen ion concentration) ≥ 7.3)
* BMI ≥ 35kg/m2
* FEV1/FVC (Forced Expiratory Volume at 1 second/Forced Vital Capacity) \> 70%

Exclusion Criteria:

* Persistent hypercapnic respiratory acidosis defined as pH \<7.30
* Severe hypoxic and/or hypercapnic respiratory failure defined as a PaO2 (Partial Pressure of Oxygen)\< 7.0kPa and/or a PaCO2 \> 9kPa (kilopascal)
* Failure to tolerate NIV during initiation or if required to treat acute decompensation
* Hypercapnic respiratory failure requiring intubation within the last 28 days
* Hypercapnic respiratory failure secondary to an identifiable cause other than obesity
* Acute coronary syndrome or unstable angina
* Cognitive impairment that would prevent informed consent into the trial and/or inability to comply with the protocol
* Psychiatric disease necessitating anti-psychotic medication, ongoing treatment for drug or alcohol addiction, persons of no fixed abode post-discharge
* Patients undergoing renal replacement therapy
* Patients with co-existent cancer and a prognosis likely to be less than 12-months
* Critical peripheral vascular disease awaiting re-vascularisation procedure (or claudication distance \<100 metres)
* Stroke with hemiparesis
* Age \<18 years
* Pregnant