Ross 1993 SURVIVAL.

Study characteristics
Methods	Cluster‐randomised trial conducted in Ghana
Participants	Eligibility: children aged 6–90 months Excluded: children with xerophthalmia Sample: 185 clusters that included 21,906 children. 51.5% boys
Interventions	Experimental group: vitamin A 100,000 IU for children aged 6–11 months and 200,000 IU for older children + vitamin E 20 IU Control group: placebo + vitamin E 20 IU Study duration: intervention delivered every 4 months for 24 months
Outcomes	All‐cause mortality and cause‐specific mortality due to diarrhoea, respiratory disease, measles and meningitis; mean vitamin A serum levels; malaria prevalence
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "Randomisation was blocked in both studies to ensure similar numbers of children in each group in each part of the study area". Comment: explicit methods for generating allocation sequence not available.
Allocation concealment (selection bias)	Low risk	Quote: "Randomisation was carried out in London by an independent statistician, who held the randomisation code and who also did an interim analysis of the mortality results from the Survival Study for the trial's data‐monitoring committee after a year of follow‐up". Comment: code was protected for the duration of trial.
Blinding (performance bias and detection bias) Blinding of participants	Low risk	Quote: "Vitamin A and placebo were supplied by Hoffmann‐La‐Roche's Sight and Life Programme, and were similar in taste and colour. In the Survival Study, liquid vitamin A or placebo was supplied in opaque 150 mL bottles containing 20 IU/mL vitamin E alone (placebo) or plus 100,000 IU/mL retinol equivalent as retinyl palmitate (vitamin A) in purified peanut oil. Each bottle had a unique number, and was labelled with a cluster code before despatch to Ghana". Comment: probably done.
Blinding (performance bias and detection bias) Blinding of provider	Low risk	Comment: as above; probably done.
Blinding (performance bias and detection bias) Blinding of outcome assessor	Low risk	Comment: in view of the blinding procedures in place elsewhere in the study, this was probably adequate.
Incomplete outcome data (attrition bias)	Unclear risk	Comment: 8.4% (1847) children lost to follow‐up and similar between groups. The reasons for losses to follow‐up were not provided.
Selective reporting (reporting bias)	High risk	Comment: authors collected data on night blindness, Bitot's spots and xerophthalmia, but did not report them.
Other bias	Unclear risk	Comment: the method for inflating the CIs was not well‐described. No ICC reported