Two review authors (AB, EA) independently assessed
the risk of bias of each study using the criteria listed below,
which were taken from the Cochrane Risk of Bias tool in
RevMan 5.1:
Random sequence generation (selection bias)
Allocation concealment (selection bias)
Blinding (performance bias)
Incomplete outcome data (attrition bias)
Selective reporting (reporting bias)
Other bias
Any discrepancies were resolved by discussion (see
online Appendix 2).
We did not use the