Results
We found 1916 records, including 33 relevant RCTs with at least 45 participants (Fig. 1). Online Tables DS1 and DS2 list methodological characteristics, SES and quality ratings; Table DS1 contains the findings from interventions for which there appeared to be adequate evidence, and Table DS2 contains those for which there was not adequate evidence (either evidence that they were not effective or where there was simply insufficient evidence).