Salama 2015.

Methods	Study design: quasi‐randomised controlled trial Setting: single‐center NICU in Jordania Duration of study: January 2011 to December 2011
Participants	Preterm infants born at gestational age 28‐34 weeks with RDS, including positive chest x‐ray (Downe's score)
Interventions	NIPPV delivered via ventilator (Neoport E100M; DRE Medical, Louisville, KY, USA) by nasal cannula. Synchronized mode. Settings: PIP 5‐12 cmH2O, PEEP 4‐6 cmH2O, Ti 0.3‐0.5 seconds. Bubble CPAP delivered via nasal cannula, PEEP 6 cmH2O
Outcomes	Primary outcome: failure of noninvasive ventilation Secondary outcomes: duration of mechanical ventilation, nasal injury, abdominal distention, GI perforation, air leak, BPD, sepsis, IVH
Notes	Mixed population: Some infants received prophylactic surfactant via INSURE (< 29 weeks) or rescue surfactant if needed, before randomization.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	High risk	Quasi‐randomized trial; allocation based on admission number (odd or even)
Blinding (performance bias and detection bias) All outcomes	High risk
Incomplete outcome data (attrition bias) All outcomes	Low risk
Selective reporting (reporting bias)	Low risk
Other bias	High risk	No flow diagram