Nilius 2006.

Methods	Randomised, parallel group trial
Participants	N = 51 participants; mean age: 57 years; AHI: 53.3 Inclusion criteria: AHI > 20 Exclusion criteria: Inability to follow instructions, failure to give informed consent, acute infection, acute cardiac disease such as acute coronary artery syndrome, NYHA grade 3 or 4 heart failure, and acute pulmonary thromboembolism
Interventions	CPAP with expiratory pressure relief versus fixed CPAP Study duration: 7 weeks
Outcomes	Machine usage (average hours used) AHI Symptoms (ESS)
Funding & conflicts of interest statements	Quote: "This study was financed by a gift from Heinen U. Lowenstein. Dr. Ruhle has received research funding from Fisher A. Paykel, Heinen U. Lowenstein, ResMed, and Weinmann, but this funding has gone into department funds. Dr. Nilius, Andreas Happel, and Ulrike Domanski have reported to the ACCP that no significant conflicts of interest exist with any companies/organizations whose products or services may be discussed in this article."
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Information not available; requested
Allocation concealment (selection bias)	Low risk	Third party responsible for randomisation and setting machines to relevant treatment mode
Blinding of participants and personnel (performance bias) Machine usage, symptoms, quality of life, withdrawal, adverse effects	Low risk	Quote: "The patients were informed that they would receive two different forms of treatment .....but were given no further details...........The technician had no information from the investigators about the modality that the patients were receiving"
Blinding of participants and personnel (performance bias) AHI, blood pressure, treatment pressure	Low risk	These outcomes unlikely to be affected by awareness of treatment group.
Blinding of outcome assessment (detection bias) Machine usage, symptoms, quality of life, withdrawal, adverse effects	Low risk	Quote: "The physician and technicians reviewing the polysomnographic data and performing the manual CPAP titration were blinded to the treatment mode employed"
Blinding of outcome assessment (detection bias) AHI, blood pressure, treatment pressure	Low risk	These outcomes unlikely to be affected by awareness of treatment group.
Incomplete outcome data (attrition bias) All outcomes	Low risk	All participants accounted for in analysis
Selective reporting (reporting bias)	Low risk	All outcomes reported
Other bias	Low risk	No concerns identified