Mainz 2015.

Study characteristics
Methods	RCT. Design: double‐blind, cross‐over design. Duration: 1st arm of 28 days followed by a 28‐day washout period and then alternative treatment for 28 days. Location: multicentre in Germany.
Participants	69 people with CF.
Interventions	Group 1: HS 6% via PariSinusTM. Group 2: IS via PariSinusTM.
Outcomes	Primary outcome Sinonasal outcome test (SNOT‐20) upper airway symptoms or disease‐specific QOL. Secondary outcomes Rhinoscopy, rhinomanometry, cytokines in nasal lavage.
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Stated but not defined.
Allocation concealment (selection bias)	Unclear risk	This was stated but not described.
Blinding of participants and personnel (performance bias) All outcomes	High risk	No attempt was made to blind the taste of the HS solution.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Stated but not described in detail.
Incomplete outcome data (attrition bias) All outcomes	Low risk	All drop outs clearly defined.
Selective reporting (reporting bias)	Low risk	All outcomes that were stated were described.
Other bias	Low risk	No other major source of bias detected.