Varekojis 2003a

Methods	RCT. Cross‐over design (no washout). Location: single centre in USA. Duration: 2 days in each arm which were consecutive so 6 days in total.
Participants	28 participants recruited, 24 (10 females, 14 males) analysed, reasons for withdrawals not reported. Mean age 24 years, range 14 ‐ 34 years.
Interventions	PD&P versus IPV versus HFCWO. 3 treatments per day each lasting 30 min (24 min of therapy followed by 6 min of directed coughing). PD&P was delivered by pulmonary nurses; IPV and HFCWO delivered by respiratory therapists. This suggests inconsistency of personnel when delivering treatment modalities.
Outcomes	Wet and dry sputum weight collected over the 60‐minute period, participant satisfaction questionnaire.
Notes	This study ID refers to the IPV versus PD&P section of the study. It is not clear whether sputum was collected for each of the 6 treatment days or for first or last 60 min per treatment technique. Study reports that 4 participants received each of the 6 possible treatment sequences ‐ this suggests that they had more than 1 admission during the study time which may lead to duplication of data.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Described as randomised, but method not discussed.
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	4 withdrawals following randomisation, but reasons for withdrawals not reported.
Selective reporting (reporting bias)	Low risk	Limitations of the study were outlined.
Other bias	High risk	Study reports that 4 participants received each of the 6 possible treatment sequences ‐ this suggests that they had more than 1 admission during the study time which may lead to duplication of data. Pulmonary nurses were used to perform physiotherapy techniques which may have had an impact on the accuracy and efficacy of treatments delivered.