Reddy 1986a.

Study characteristics
Methods	Factorial design, individually randomised trial conducted in India
Participants	Eligibility: children aged 1–5 years Excluded: children without parental consent Sample: 487 children. Mean age and proportion of boys not reported
Interventions	4 intervention groups Experimental group I: oral administration of L‐tetramisole 50 mg followed 3 days later by vitamin A 200,000 IU Experimental group II: vitamin A 200,000 IU Experimental group III: L‐tetramisole 50 mg orally Control group: placebo
Outcomes	Mean vitamin A serum levels
Notes	Data included in 2 sets
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "After the baseline survey, the children were assigned, randomly, into four groups, matched for age, anthropometry, serum vitamin A, and worm infestation and the following treatment was given". Comment: insufficient details provided to make a judgement.
Allocation concealment (selection bias)	Unclear risk	Comment: insufficient information to permit judgement.
Blinding (performance bias and detection bias) Blinding of participants	Unclear risk	Comment: insufficient information to permit judgement.
Blinding (performance bias and detection bias) Blinding of provider	Unclear risk	Comment: insufficient information to permit judgement.
Blinding (performance bias and detection bias) Blinding of outcome assessor	Unclear risk	Comment: insufficient information to permit judgement.
Incomplete outcome data (attrition bias)	Unclear risk	Comment: insufficient information to permit judgement.
Selective reporting (reporting bias)	Unclear risk	Quote: "After 6 months and 12 months, heights and weights were measured, clinical status was assessed and morbidity for the preceding one month was recorded. Finger‐prick blood samples were collected and serum vitamin A levels were estimated, stool samples were examined for the presence of ascaris ova and other parasites". Comment: authors did not report height or weights, or detailed data on clinical status or morbidity.
Other bias	Unclear risk	Comment: insufficient information to permit judgement.