Willett 1979

Methods	RCT Length of follow‐up: 12 months
Participants	All children living in endemic area Number analysed for primary outcome: 268 Age range: 6 to 91 months Inclusion criteria: pre‐school children from Ubiri village who attended clinic and produced a stool sample Exclusion criteria: none stated
Interventions	Multiple doses Levamisole syrup: 2.5 mg/kg every 3 months; Flavoured sucrose syrup: every 3 months.
Outcomes	Growth rates in both groups, and subgroup of those infected; these have been corrected for various factors using analysis of covariance (unadjusted data are not reported and the growth rates are not presented with any measure of variance). Measured but not reported: height; length; stool egg count in subgroup (Kato method); growth rates using least square method.
Notes	Location: Tanzania Community category: 3 Source of funding: Research and Publications Committee, University of Dar es Salaam. Analysis was supported by a training grant (HL 05998‐04) from the National Heart, Lung and Blood Institute, NIH, DHEW Bethesda, MD.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Random‐numbers table.
Allocation concealment (selection bias)	Unclear risk	No details reported.
Blinding (performance bias and detection bias) All outcomes	Low risk	"children were weighed and measured as before by a person unaware of their treatment status"; placebo and treatment given as a flavoured syrup.
Incomplete outcome data (attrition bias) All outcomes	High risk	78% (268/341) of randomized participants were evaluated; inclusion of all randomized participants (number evaluable/number randomized): 78% (268/341).
Selective reporting (reporting bias)	High risk	Not all pre‐specified outcomes reported.
Other bias	Low risk	No obvious other source of bias.