Methodological rigor of included studies.

Note.aComparison groups were equivalent on all socio-demographic variables except religion.bSchools are used as the unit of analysis in this paper. Authors do not report whether the individual participant follow-up rate at each of these schools was for greater than 80%.cRandom assignment specified in Huang et al., 2008, not Ye et al., 2009, but articles are reporting on the same study.n/a: not applicable; nr: not reported.