Gaskin 1998.

Study characteristics
Methods	Single‐centre (Toronto, Canada) prospective parallel design RCT 66 participants (with CF attending adult and paediatric clinics) were "randomly assigned" to standard PD and percussion (CCPT) or PEP mask therapy (Astra Meditec) for 2 years.
Participants	66 participants, 61 participants completed. Mean age 21.6 (SD 8.3) at enrolment; age range 11–45 years 34 males, 32 females CCPT: mean age 21.9 (SD 8.7) years PEP: mean age 21.3 (SD 8.0) years
Interventions	CCPT PEP No indication of frequency or duration of, or adherence with each prescription.
Outcomes	Followed up every 3 months for 2 years: FVC, FEV1, QoL (Quality of Well Being score), Brasfield CXR score, exercise testing (cycle ergometry). Compliance and exercise diaries kept by participants.
Notes	Study reported in 1 abstract from 12th NACF conference (Gaskin 1998). Jadad score: 2/5.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Not reported: (quote) "patients were randomly assigned". Numbers assigned to each group not reported.
Allocation concealment (selection bias)	Unclear risk	Not described.
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Not feasible (participants), not described (personnel).
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Not described.
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	5 participants (gender not reported) withdrew from study (0 lost to follow‐up): 4 withdrew from CCPT group immediately after randomisation; 1 from PEP group moved away.
Selective reporting (reporting bias)	High risk	Only baseline FEV1 and rate of decline trajectory provided. Secondary analysis of FEV1 data included only those aged < 19 years (unclear how many) and those compliant with treatments (unclear how many). No other outcome data reported – FVC, CXR score, QoL and exercise test results were absent. Compliance data not reported.
Other bias	High risk	Analysis with or without the withdrawn and non‐compliant participants in secondary analysis did not change the conclusions of the study. Numbers of non‐compliant participants were not reported. Conclusions that PEP was "valid alternative" to CPT not supported by results reported.