Oermann 2001.

Study characteristics
Methods	RCT. Cross‐over design (2‐week washout period). Location: multicentre (3 centres) in USA. Duration: 12 weeks (2‐week run in period followed by 4‐week treatment and 2‐week washout with alternative 4‐week treatment).
Participants	29 participants enrolled (14 males). Aged 6 years or greater. Mean (range) age ‐ 23 (9 to 39) years. Diagnosis of CF confirmed by sweat test. Required ability to reliably perform spirometry and lung volume measurements, to have baseline FVC of 50 ‐ 80 % predicted and be clinically stable for 1 month prior to enrolment. Excluded if in concurrent study or history of massive haemoptysis within 1 month or pneumothorax within 6 months of entrance. 5 participants withdrew (4 exited due to illness and 1 due to non‐compliance with clinic visits).
Interventions	HFCWO versus oscillating PEP (flutter). As prescribed previous to study ‐ no mention whether this was 2x daily etc. 4 weeks in each arm, 2‐week lead‐in and wash out periods during which time they resumed their normal routine therapies which were not outlined.
Outcomes	FEV1, FVC, FEF25-75%, participant satisfaction scores in domains of efficacy, convenience and comfort. Participant preference was measured as baseline and pre/post each intervention (5 data points).
Notes	5 withdrawals, ITT was identified.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Prospective randomisation, further details not given on method.
Allocation concealment (selection bias)	Unclear risk	Not discussed.
Blinding (performance bias and detection bias) All outcomes	Unclear risk	Not discussed.
Incomplete outcome data (attrition bias) All outcomes	Low risk	5 participants withdrew (4 exited due to illness and 1 due to non‐compliance with clinic visits). ITT identified.
Selective reporting (reporting bias)	High risk	Only participants who completed both therapies were included in the final analysis. As we do not know what their normal therapy was perhaps they had already done a comparison?
Other bias	Unclear risk	None identified.