Steen 1991.

Study characteristics
Methods	Single‐centre (Belfast, Northern Ireland), cross‐over RCT 28 participants with CF were randomly allocated to 1 of 4 treatment groups, each to be carried out for 4 weeks with no washout period, comprising: CCPT and FET, 5 min PEP plus CCPT and FET, PEP alone, and PEP and FET alone. All participants were fully assessed after each 4‐week intervention before being randomly allocated to 1 of the remaining treatment groups.
Participants	28 participants were recruited aged 8–21 years (5 severe, 14 moderate, 9 mild disease) with confirmed CF diagnosis (elevated sweat sodium > 70 mmol on 2 occasions) who were able to co‐operate with pulmonary function testing and "highly motivated" to complete the trial. Gender split of population not described. 24 completed the trial, 4 withdrawals: 1 severely affected girl of 18 years died; 1 girl of 8 years became non‐compliant and 2 girls asked to be withdrawn (1 after developing a pneumothorax while on CCPT plus PEP and 1, who was a copious sputum producer, withdrew after 2 days on CCPT plus PEP "as PEP alone was failing to clear secretions" – she had previously carried out PEP alone, which she considered was as effective as CCPT but no better).
Interventions	Bronchodilator response was assessed by recording PEFR using a Wrights Peak Flow Meter, before and 30 min after salbutamol nebuliser (dose 2.5 mg). PEFR improved by ≥ 10% in 4 participants who had inhaled bronchodilators prior to each physiotherapy treatment throughout the study. CCPT: a combination of PD (the drainage positions as described by Kendig and Clarwick (Kendig 1977)), percussion, breathing exercises and FET consisting of 1 or 2 forced expirations with an open glottis from mid‐lung volume to low‐lung volume followed by a period of relaxed controlled diaphragmatic breathing. CCPT plus PEP: 5 min PEP followed by CCPT as above. PEP delivered using an Astra or Vitapep mask. The participant sat with elbows resting on a table, applied the face mask firmly and, using a slightly active expiration, the outflow valve was adjusted to give an expiratory resistance of 10–15 cmH2O. The participant breathed through the mask 10–15 times followed by forced expiration and cough, if required. The cycle was then repeated. PEP alone: in the sitting position as above. PEP and FET: PEP and FET as described above in the sitting position. FET alone: 5 older participants with "good FET" agreed to carry out FET alone as a separate treatment arm. The treatments were carried out consecutively with no wash‐out period.
Outcomes	Participants initially underwent clinical assessment and CXR and were given Shwachman and Chrispin‐Norman scores. Daily diaries were kept noting changes in cough, sputum characteristics, wheeze, appetite, exercise tolerance and shortness of breath. Sputum was sent for culture each month and during acute exacerbations. Participants also noted their general impression about each treatment. Data presented on Shwachman and Chrispin‐Norman scores, weight of sputum and pulmonary function (FEV1, FVC, PEFR). Although not explicitly described, presumably the data collection procedure described at baseline was reproduced at each visit: a physiotherapy treatment was carried out with pulmonary function tests being recorded before and at 20 min and 120 min after the completion of treatment. PEFR was measured and FVC and FEV1 using a Vitalograph spirometer. Sputum was collected and weighed over this 2‐hour period.
Notes	Study is reported in 1 abstract (Steen 1985, n = 25) and 1 full‐text manuscript (Steen 1991, n = 28), which is the primary reference for this study. Jadad score: 2/5.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Not reported: participants were "randomly allocated."
Allocation concealment (selection bias)	Unclear risk	Not described.
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Not feasible (participants), not reported (personnel).
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Not described.
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	4 withdrawn (1 death, 1 non‐compliant, 1 pneumothorax and 1 considered treatment was ineffective).
Selective reporting (reporting bias)	High risk	Only 1 pulmonary function figure reported for each intervention. Unclear whether this was from the test recorded before or 20 min or 120 min after the completion of treatments. No numerical data provided for between‐group changes: reported as "no significant alteration" in growth, Shwachman and Chrispin‐Norman scores neither was there any significant change in pulmonary function tests or expectorated sputum weight (between any of the 5 treatments). Data from daily diaries not reported (changes in cough, sputum characteristics, wheeze, appetite, exercise tolerance and shortness of breath).
Other bias	High risk	No between group baseline comparison data provided. No washout period between interventions, so risk of carry‐over effects. If only 'highly motivated' participants were recruited, this may have introduced a selection bias. Preferences reported anecdotally, rather than numerically, e.g. "parents of younger children reported …", "23 … replied that this combination improved their independence and, at the same time, was still an effective form of chest physiotherapy." Infidelity in description of dropouts: 24/28 completed, but text was not consistent with descriptions of treatments: "one on developing a pneumothorax while on Treatment B (CCPT plus 5 min PEP) and one, who was a copious sputum producer, withdrew after 2 days on Treatment B (CCPT plus 5 min PEP) 'as PEP alone was failing to clear secretions'. She had previously carried out Treatment C (PEP alone), which she felt was as effective as CCPT but no better." It is unclear why Treatment B (CCPT plus 5 min PEP) is described as 'PEP alone'. Discrepancy in age range of participants between 1985 abstract (8–22 years) and 1991 paper (8–21 years) An additional 5th intervention (FET alone) was performed by a subset of 5 participants, after the 4 randomly assigned interventions. This was an ad hoc addition and not part of the a priori RCT. 23/24 participants apparently chose PEP with FET as their long‐term therapy. The final participant's preference was not reported. Astra Medical and Vitalograph provided PEP masks for the study.