Engle 1955.

Methods	Randomization was by a modified random allocation technique (method not stated), so it is assumed that infants were truly randomized. It appears there was no blinding of either the intervention or outcome assessment. No power calculations were done. There was a 77% follow up rate at 6 months, but only 51% of infants underwent developmental assessment at 12 months age.
Participants	Infants less than 1650g birth weight were eligible to participate. 99 infants were randomized. Of these only 9 were <1000g BW. Birth weight range: 800‐1650g. Gestational age range: 26‐40 weeks. Infants 1000g or less were randomized at 14 days, those with birth weights 1001‐1361 at 7 days, and those 1362‐1650g at 2 days.
Interventions	All infants received supplementary oxygen for at least 5 days. Experimental group (early weaning): were assigned at Day 2, 7, or 14 (depending on birth weight) to be weaned from oxygen gradually over 3‐4 days. Thus removal from oxygen was at approximately 5, 10 or 17 days. Control group (late weaning): infants were given unrestricted oxygen until they reached 1600g, and were then weaned gradually over 3‐4 days.
Outcomes	Mortality (any) RLF (vascular, any stage) RLF (cicatricial, any grade) RLF (cicatricial, severe grades) Valid mortality and eye outcome data only available to 6 weeks of age. There was 1 death on day 11 (early weaning group), and four losses to follow up by 6 weeks (2 in each group). The loss to follow up rates at 6 and 12 months were 24% and 50% respectively. Hence long term developmental outcomes were not analysed for this review.
Notes	Authors reported results in three groups: experimental (group II, early weaning), control (group I, late weaning), and a group that were randomized to the experimental group but received the control intervention (group II ‐> I). The analyses for this review were undertaken on an intention‐to‐treat basis i.e. those in group II ‐> I were analysed as they were originally randomized in group II.
Risk of bias
Bias	Authors' judgement	Support for judgement
Adequate sequence generation?	Unclear risk	Modified random allocation. It was unclear how this method worked.
Allocation concealment?	High risk	It was not stated whether allocation concealment was used.
Blinding? All outcomes	High risk	It was impossible to blind participants to early and late discontinuation of oxygen (or assisted ventilation).
Incomplete outcome data addressed? All outcomes	High risk	There were 9 tables of results and analysed data that reported on all outcomes, but there was only a 77% follow up rate at 6 months, and only 51% of infants underwent developmental assessment at 12 months age.