Tyrrell 1986.

Methods	RCT. Cross‐over design. Each treatment given for 1 month.
Participants	CF diagnosed by the Nottingham City Hospital Cystic Fibrosis Clinic. 19 participants (after withdrawals, 9 females and 7 males); mean age 13 years, range 10 ‐ 18 years; mean Schwachman score 62, range 47 ‐ 85 points.
Interventions	2 interventions:There was no washout period between each treatment period. 1. PEP treatment ‐ pressure 10 ‐ 15 cm H₂O; seated participants exhaled 10 times through an Astra mask, followed by "forced expiratory coughing"; 2. PDP ‐ participants received percussion and performed coughing in PD positions. Treatment was performed for 20 minutes, twice daily.
Outcomes	FEV 0.75, FVC, PEFR were recorded before, 20 minutes after, and 90 minutes after a single supervised treatment at the beginning of the randomisation month. Wet weight of sputum expectorated during the therapy was also measured. The same measures were repeated over a single treatment at the end of the randomisation month. In addition, during each treatment month, diary card records were kept regarding the following symptoms: sleep, cough, wheeze, activity, sputum production. (Details of the scoring system for these symptoms are not provided.) Although not listed as a formal outcome measures, antibiotic use and participant preference are also discussed in the results section.
Notes	3 withdrawals due to non‐adherence. Those children who showed airway reversibility with salbutamol were asked to use it before treatment throughout the whole study. Published paper.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Described as randomised, no further information provided.
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	Unclear risk	3 withdrawals due to non‐adherence.
Selective reporting (reporting bias)	High risk	Not all outcomes were reported in full.
Other bias	High risk	There was no washout period between each treatment period, thus there is a potential for a carryover effect.