Data extraction and management
We designed a formto extract data. For eligible studies, two review
authors extracted the data using the agreed form. We resolved
discrepancies through discussion. We entered data into Review
Manager software (RevMan 2014) and checked for accuracy.
Assessment of risk of bias in included studies
Two review authors independently assessed risk of bias for each
study using the criteria outlined in the Cochrane Handbook for
Systematic Reviews of Interventions (Higgins 2011) and resolved
any disagreements by discussion.