Newbold 2005.

Study characteristics
Methods	RCT. Parallel design. Location: single centre in Canada. Duration: 13 months.
Participants	43 adults (25 males) with CF. FEV1 > 40% predicted. No hospitalisations within 1 month of study entry, no change in medications within 1 month of study entry and willingness to attend 5 follow‐up appointments. Exclusion criteria ‐ absence of daily cough or daily production of sputum. Flutter group: mean (SD) age 31 (8.5) years. PEP group: mean (SD) age 28 (8.1) years.
Interventions	Flutter versus PEP mask (21 randomised to each treatment group out of 42 participants included in analysis) 5 ‐ 10 exhalations through the flutter with the degree of tilt adjusted to optimise the vibrations. Cycle is repeated until the individual felt "clear" or for approximately 20 minutes. 10 ‐ 15 breaths through the PEP followed by a huff or cough, followed by period of relaxed breathing. Cycle repeated 5 ‐ 6 times taking approximately 20 minutes to complete. Participants were advised to perform their therapy 2x per day following any bronchodilator therapy. They were instructed to only use their Ffutter or PEP mask for the duration of the study. Followed every 3 months for 13 months. First month was the "training" month.
Outcomes	Lung function tests (FEV1, FVC, FEF25-75%), Quality of Well‐being Scale, Chronic Respiratory Disease Index Questionnaire, daily diary record.
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Random numbers table and block randomisation.
Allocation concealment (selection bias)	Low risk	Sealed opaque envelope. Envelopes opened in sequence, and this may itself be a risk of allocation bias.
Blinding (performance bias and detection bias) All outcomes	Low risk	Lung function assessor was blinded to the device used by the participant and also to what stage they were at in the study period. It was not possible to blind the physiotherapist teaching the participant how to use the device nor indeed the participant themselves.
Incomplete outcome data (attrition bias) All outcomes	Low risk	One drop out due to not attending at clinic appointments. Paper states that although not all participants attended every follow up assessment, baseline and final measures were obtained for all 42. All but 3 (1 flutter; 2 PEP) attended at least 4 follow‐up visits in the 13‐month period.
Selective reporting (reporting bias)	Low risk	Information available for all outcome variables measured.
Other bias	High risk	Flutter group and PEP group had different mean pulmonary function values at recruitment (flutter group higher). This led to divergence between groups in mean pulmonary function values at 1st and 2nd follow‐up visits. Study fatigue is always a consideration when using small populations such as those with CF; and this study this as a reason why some participants declined inclusion into the study