Qiao 2017

Methods	Single‐blind randomised controlled trial Study location: NICU of the First People's Hospital in Kunshan, Jiangsu Univeristy, People's Republic of China Study period: February 2014 to June 2014
Participants	96 preterm infants, PMA 28 to 34 weeks' gestation
Interventions	Control group receiving standard parenteral nutrition (group 1: n = 31), iron‐supplemented group (iron sucrose (IS)) (group 2: IS, n = 33), and iron‐supplemented combined erythropoietin group (group 3: IS + EPO, n = 32). IS + EPO group received EPO 400 IU/kg twice a week for 2 weeks; total dose 800 IU/kg per week (1600 IU/kg in 2 weeks) (high dose). IS group and IS + EPO group received iron 200 µg/kg/d until 2 weeks after birth.
Outcomes	NEC ROP Mortality
Notes	For outcomes, we included the IS group and the IS + EPO group.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	No information provided
Allocation concealment (selection bias)	Low risk	Participants were randomly assigned to 1 of 3 groups in the following manner: Treatment cards were imprinted with a unique randomisation code and were placed in sequentially numbered opaque envelopes. At the study site, treatment cards were taken out in sequential order, and participants were assigned to the corresponding treatment group on the basis of the randomisation number.
Blinding of participants and personnel (performance bias) All outcomes	Low risk	All investigators, physicians, and nurses involved in participant care and parents were blinded to group assignment. The randomisation process was made available only to the pharmacist, who supervised the quality of iron sucrose and the parenteral nutrition preparation.
Blinding of outcome assessment (detection bias) All outcomes	Low risk	All investigators, physicians, and nurses involved in participant care and parents were blinded to this assignment. The randomisation process was made available only to the pharmacist, who supervised the quality of iron sucrose and the parenteral nutrition preparation.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Of 96 preterm infants enrolled, 91 infants completed the study; 30 belonged to the control group, 31 to the iron‐supplemented (IS) group, and 30 to the iron‐supplemented (IS) + EPO group. Five infants could not complete the study. One infant in the IS group died from respiratory failure, and 4 infants (1 in the control group, 1 in the IS group, and 2 in the IS + EPO group) were discharged because treatments were discontinued by their parents.
Selective reporting (reporting bias)	Unclear risk	Study protocol was not available to us, and we cannot judge whether deviations from the protocol occurred.
Other bias	Low risk	Appears free of other bias.