Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: “The process of randomisation was as follows. The communities were placed into three strata based on the distance of the clinic from a tarred road. There were 16 299 360 ways that the 30 communities could be allocated to the two arms ensuring balance across these strata. Randomisation was then restricted to ensure an equal number of schools in each arm; balance across districts; and an average sample size per community between 255 and 261 in each arm. The 8575 allocations satisfying these conditions were listed, and one was selected randomly at the randomisation meeting.”—Cogan 2008 Comment: insufficient information to permit judgement
Allocation concealment (selection bias)	Low risk	Comment: intervention and comparison sites were different
Similar baseline characteristics	Unclear risk
Similar baseline outcome measurement	Unclear risk
Blinding of participants and personnel (performance bias)	Low risk	Comment: participants could not be blinded due to the nature of the intervention
Blinding of outcome assessment (detection bias)	Unclear risk	Comment: insufficient information to permit judgement
Incomplete outcome data (attrition bias)	High risk	Comment: high amount of loss to follow up from both intervention and control groups
Prevention of knowledge of allocated intervention	Unclear risk
Protection against contamination	Unclear risk
Selective reporting (reporting bias)	Unclear risk	Comment: pre‐specified outcomes in the 2008 paper by the same author, were reported; but no protocol was found.
Other bias	Low risk	Comment: the study appears to be free from other bias