Kumar 1992.

Methods	Single centre Randomization ‐ yes, undertaken in the pharmacy with sealed envelopes Blinding of intervention ‐ no Completenes of follow up ‐ unknown Blindness of outcome assessment ‐ unknown
Participants	24 preterm infants with recurrent apnea, 11 allocated to caffeine and 13 to theophylline
Interventions	Caffeine citrate 20 mgs/kg loading dose, 5 mg/kg/24 hrs maintenance Theophylline 5.5 mg/kg loading dose, 1.1 mg/kg 6 hrly maintenance
Outcomes	Days 1, 3 and 7 Apnea ≥ 15 sec / 12 hr Bradycardia < 80 / 12 hrs SaO2 < 85 / 12 hrs
Notes	Only published as an abstract but additional information regarding randomisation methods and dosages of caffeine and theophylline provided by author.
Risk of bias
Bias	Authors' judgement	Support for judgement
Allocation concealment (selection bias)	Low risk	Randomization ‐ yes, undertaken in pharmacy with sealed envelopes
Blinding (performance bias and detection bias) All outcomes	High risk	No blinding of interventions or outcome assessment
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Not stated
Selective reporting (reporting bias)	High risk	Comment from author
Other bias	Low risk	Only published as abstract but additional information given by author