Table 2

Risk of bias assessments

StudyRandom sequence generationAllocation concealmentBlinding of participant and personnelBlinding of outcome assessmentIncomplete outcome dataSelective reportingOther biases
Göpel et al27Low riskLow riskHigh riskHigh riskLow riskLow riskCriteria for providing surfactant were not similar across the two groups
Kanmaz et al28UnclearLow riskHigh riskHigh riskLow riskLow risk
Mirnia et al29UnclearUnclearHigh riskHigh riskLow riskUnclear*
Bao et al30Low riskUnclearHigh riskHigh riskLow riskUnclear†Trial stopped early
Mohammadizadeh et al31UnclearLow riskHigh riskHigh riskLow riskHigh‡
Kribs et al32Low riskLow riskHigh riskHigh riskLow riskLow risk
  • *Trial protocol not registered in a public trial registry.

  • †Trial protocol registered after completion of the study.

  • ‡Outcomes of common neonatal morbidities, that is, NEC, ROP and PDA requiring treatment not provided.

  • NEC, necrotising enterocolitis; PDA, patent ductus arteriosus; ROP, retinopathy of prematurity.