Ruhle 2011.

Methods	Randomised, cross‐over study
Participants	N = 51 participants (gender breakdown available for 44 completers: 39 M/5 F). Age 51.5; BMI: 30.9 kg/m2; AHI: 43; ESS 10.3 Inclusion criteria: all patients referred with OSA, aged between 30 and 80 and without nasal or throat complaints Exclusion criteria: > 5 central apnoeas per hour of sleep, acute infection, NYHA III or IV heart failure, acute pulmonary embolism or acute coronary syndrome. Previous use of CPAP
Interventions	CPAP with heated humidification versus CPAP without heated humidification Study duration: 2 x 4 weeks
Outcomes	Machine usage (average hours used) Tolerability
Funding & conflicts of interest statements	Quote: "K‐H. Ruhle and G. Nilius received research funding from Fisher & Paykel Healthcare, Heinen und Löwenstein, ResMed and Weinmann. This funding has gone into department funds. The author's study was supported by a grant from Fisher & Paykel Healthcare Germany GmbH & Co. KG, 73636 Welzheim, Germany.Karl‐Josef Franke and Ulrike Domanski have no financial or other potential conflict of interest associated with this investigation."
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	The study had a randomised, cross‐over design and used a previously prepared randomisation list.
Allocation concealment (selection bias)	Low risk	Quote: "The patients were told about the group allocation only after consent. The recruiting doctor was blinded to the randomisation."
Blinding of participants and personnel (performance bias) Machine usage, symptoms, quality of life, withdrawal, adverse effects	High risk	Quote: "However, it must be kept in mind that patients knew when cHH was used and this may impact on the reported symptoms"
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	High risk	Quote: "The outcome assessor who calculated the study results was not blinded to the allocation."
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	High risk	Quote: "Fifty one patients were recruited, 7 dropped out during the course of the study, of which 5 were allocated to the humidification group and 2 in the CPAP group.....44 patients completed the study."
Selective reporting (reporting bias)	Low risk	All outcomes were reported
Other bias	Low risk	No concerns identified