Castile 2009.

Methods	Randomised double‐blind placebo‐controlled trial. Cross‐over design. Duration: 6 months for each treatment arm, but no washout period stated.
Participants	24 infants, clinically well at time of entry into trial. Not stated how many in each group. Age: mean (SD) 42 (32) weeks. Gender distribution not stated.
Interventions	Treatment: nebulised rhDNase 2.5 mg once daily. Control: placebo once daily.
Outcomes	Included in this trial: changes in infant PFTs (% predicted and z scores for change in FEV0.5) Not included in this review: FEF25‐75, RV/TLC, change in CT score, change in air trapping, antibiotic treatment days.
Notes	Only data for 19 infants for LFTs and 21 infants for CT scans. Data only available from abstract
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Described as randomised but no details given
Allocation concealment (selection bias)	Unclear risk	Not stated in abstract.
Blinding (performance bias and detection bias) All outcomes	Low risk	Investigators and parents blinded to treatment group.
Incomplete outcome data (attrition bias) All outcomes	High risk	Follow up lung function data for only 19 of 24 recruited and CT scan data for only 21 of 24 recruited infants were reported. Not clear which groups infants dropped out from.
Selective reporting (reporting bias)	Unclear risk	Antibiotic treatment days not reported.
Other bias	Unclear risk	Cross‐over design with no stated washout period (abstract only).