Viscardi 1997.

Methods	Randomised, prospective, double‐blind, placebo‐controlled trial Blinding of randomisation: yes Blinding of intervention: yes Complete follow up: yes Blinding of outcome: yes, CXRs were reviewed by a single observer blinded to the treatment regimens
Participants	Number of infants entered into the study: 26 Mean BW (SD): 687 ± 46 g in the treatment group and 702 ± 35 g in the control group Mean GA (SD): 24.6 ± 0.4 weeks in the treatment group and 25.1 ± 0.4 weeks in the control group Age of enrolment into study: day 3 Other characteristics: high probability of oxygen dependence at 28 days predicted by a CLD score at 12 hours of age Exclusion criteria: documented sepsis, congenital cardiopulmonary anomalies Study location: University of Maryland Hospital Study period: not stated
Interventions	Nebulised cromolyn sodium 20 mg (n = 13) or 2 mL normal saline placebo (n = 13) every 6 hours from day 3 until day 28
Outcomes	Primary outcomes: CLD at 28 days of life and at 36 weeks' postmenstrual age. Changes in inflammatory cell populations and the cytokines in lung lavage in response to cromolyn therapy Secondary outcomes: number of ventilator days, duration of oxygen supplementation, PDA, air leak, sepsis, NEC and IVH
Notes	100% of the control group and 77% of cromolyn sodium‐treated infants received exogenous surfactant. No adverse effects that could be attributed to the administration of cromolyn sodium were noted.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Randomisation was accomplished by a computer‐generated table of random numbers.
Allocation concealment (selection bias)	Low risk	Blinding of randomisation: yes.
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Blinding of intervention: yes (however, pharmacist aware of treatment assignment).
Blinding of outcome assessment (detection bias) All outcomes	Low risk	CXRs were reviewed by a single observer blinded to the treatment regimens.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Complete follow‐up: yes.
Selective reporting (reporting bias)	Unclear risk	The protocol for the study was not available to us so we could not judge if there were any deviations.
Other bias	Low risk	Appeared free of other bias.