Stoltzfus 2001

Methods	RCT (factorial design) Length of follow‐up: 12 months
Participants	All children living in endemic area Number analysed for primary outcome: 359 in Mebendazole arm aged 6 to 59 months Age range: 3 to 56 months Inclusion criteria: all children in Kengeja village, with age reported as 3 to 56 months by parents; 3 months before planned start of trial (pre‐school children) Exclusion criteria: severe anaemia (< 70 g/L)
Interventions	Multiple doses vs placebo Mebendazole: 500 mg given every 3 months at home visits; Placebo: identical. Treatment strategy: randomized and treated all children Both groups also received: 0.5 mL ferrous sulfate (20 mg/mL); 10 mg iron daily for 1 year or placebo as per factorial design
Outcomes	Cognitive outcomes: motor and language development by parents reporting gross motor and language milestones using scoring system developed specifically for the trial; Anthropometric measures presented in a stratified manner: (< 30 months, > 30 months), and presented as proportion of children with small arm circumference, mild wasting, and stunting; Proportion of children with poor appetite, and proportion with severe anaemia are presented for the whole group; Iron indices (not disaggregated, independent of the iron randomization). Not included in review: prevalence and egg counts (no SD/SEM); motor and language scores (results of multiple regression and correlations; raw data not reported) haemoglobin (results not reported by randomized comparisons) Others measured but not reported: stool (Kato‐Katz); weight; height; malaria film; ferritin; appetite as reported by mothers
Notes	Location: Zanzibar, Tanzania Community category: 2 Factorial design, with households randomized to iron, random allocation of mebendazole by child, stratified by iron allocation and age grouped households. An iron with mebendazole treatment term was tested in all regression models, but it did not reach significance Source of funding: Thrasher Research Fund between The Johns Hopkins University and the United States Agency for International Development, AL Pharma, Baltimore, MD, and Pharmamed, Malta.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Randomized by "blocks of 4", no further details reported.
Allocation concealment (selection bias)	Low risk	Pills in bottles with unique treatment codes, assigned by 1 investigator, codes kept in sealed envelopes.
Blinding (performance bias and detection bias) All outcomes	Unclear risk	Participants and provider were blinded; unclear whether assessor was blinded.
Incomplete outcome data (attrition bias) All outcomes	High risk	52% (359/684) enrolled participants were evaluated. Inclusion of all randomized participants (number evaluable/number randomized): 52% (359/684 = 52%).
Selective reporting (reporting bias)	Low risk	All prespecified outcomes reported.
Other bias	High risk	No obvious other source of bias.