van Asperen 1987.

Study characteristics
Methods	Single‐centre (New South Wales, Australia), cross‐over RCT 13 participants with CF (stable disease and sputum producers) undertook in random order either 4 weeks of PEP mask plus forced expiration and coughing or PD and percussion plus forced expiration and coughing.
Participants	13 participants with CF (daily sputum production and no change in treatment in the 2 months prior to the study), 10 completed (2 withdrew due to acute exacerbations and 1 withdrew electively). Age range 7–18 years Gender not reported
Interventions	CCPT: standard PD with manual percussion to all areas followed by forced expiration and coughing on a twice daily basis, lasting ≥ 20 min per session. PEP: PEP mask for 10–15 breaths, achieving an expiratory pressure of 10–15 cmH2O, followed by forced expiration and coughing conducted for 20 min on a twice daily basis. No washout period described.
Outcomes	Baseline evaluation by physiotherapist of sputum volume in the hour from the commencement of the regimen; and spirometry using a vitalograph or a Collins water‐sealed spirometer with recording of FEV1, FVC and FEF25–75. Participants then completed a diary card for 4 weeks (cough score (0–3) day and night; activity score (0–3); sputum volume in the hour after each treatment and PEFR using a Wright mini‐peak flowmeter 1 hour after treatment).
Notes	Study reported in 1 short full‐text manuscript (Van Asperen 1987). Jadad score: 2/5. Published data in litres/second, but % predicted obtained from study authors.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Participants were allocated "randomly in a crossover fashion" to the treatment regimens, but no further details given.
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outcome data (attrition bias) All outcomes	High risk	3 participants did not complete: 1 withdrew electively, 2 withdrawn due to acute infective exacerbations. Not reported which treatment arm they were in, or when they withdrew. Sputum only collected from 6 participants on both occasions (quote) "Unfortunately, sputum volumes measured by the physiotherapist were too variable and also insufficient in number to draw any definite conclusions from." PEFR data only reported from 8 participants, recorded "satisfactorily" in 8/10 participants, although criteria for 'satisfactory' not provided.
Selective reporting (reporting bias)	Unclear risk	All outcomes reported, but only anecdotal impressions related to preference provided. Pretreatment pulmonary function presented as litre/second and % predicted, while post‐treatment pulmonary function only presented as litres/second.
Other bias	Unclear risk	The results were averaged for each participant over the 4‐week study period, potentially masking significant variation in clinical status. All participants were "fully active" during the treatment periods and so activity score was not used for comparison. Astra Pharmaceuticals supplied PEP masks, PEFR meters and volume measurers.

6MWT: 6‐minute walk test; ABPA: allergic bronchopulmonary aspergillosis; AD: autogenic drainage; ANC: absolute neutrophil count; ATS: American Thoracic Society; BMI: body mass index; CCPT: conventional chest physiotherapy; CF: cystic fibrosis; CFTR: cystic fibrosis transmembrane conductance regulator; CXR: chest X‐ray; ERV: expiratory reserve volume; FET: forced expiratory technique; FEV₁: forced expiratory volume in one second; FEF_25–75: average forced expiratory flow between 25% and 75% of FVC; FRC: functional residual capacity; FVC: forced vital capacity; GOR: gastro‐oesophageal reflux; h: hour; HFCC: high‐frequency chest compression; HFCWO: high‐frequency chest wall oscillation; HR: heart rate; HRR: heart rate reserve; HIC: inspiratory capacity; HRQoL: health‐related quality of life; IPV: intrapulmonary percussive ventilation; IRT: immunoreactive trypsinogen; ITT: intention‐to‐treat; IV: intravenous; min: minute; n: number; NACF: North American Cystic Fibrosis; PD: postural drainage; PEF: peak expiratory flow; PEFR: peak expiratory flow rate; PEP: positive expiratory pressure; QoL: quality of life; Raw: airway resistance; RCT: randomised controlled trial; RV: residual volume; SaO₂: oxygen saturation of arterial blood; SD: standard deviation; SGAW: specific airways conductance; SEM: standard error of the mean; SpO₂: saturation of haemoglobin with oxygen using pulse oximetry; TGV: thoracic gas volume; TLC: total lung capacity; VC: vital capacity; WBC: white blood cell.